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		e6346b7f19
		
	
	
	
	
		
			
			* Timestamped log files are written to a `sessionstore-logs` directory in the profile directory * Errors will always get written to disk, the logOnSuccess pref ensures all logs are saved even if no error has been captured * The prefs configure how much logging we do. We have more verbose logging by default in nightly/early-beta, and less (errors, warnings) in release. * Logging statements have been added to the early phases of session restore. We'll add more I'm sure as we troubleshoot specific bugs. Differential Revision: https://phabricator.services.mozilla.com/D208816
		
			
				
	
	
		
			454 lines
		
	
	
	
		
			15 KiB
		
	
	
	
		
			JavaScript
		
	
	
	
	
	
			
		
		
	
	
			454 lines
		
	
	
	
		
			15 KiB
		
	
	
	
		
			JavaScript
		
	
	
	
	
	
| /* This Source Code Form is subject to the terms of the Mozilla Public
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|  * License, v. 2.0. If a copy of the MPL was not distributed with this
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|  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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| 
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| /**
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|  * Session Storage and Restoration
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|  *
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|  * Overview
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|  * This service reads user's session file at startup, and makes a determination
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|  * as to whether the session should be restored. It will restore the session
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|  * under the circumstances described below.  If the auto-start Private Browsing
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|  * mode is active, however, the session is never restored.
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|  *
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|  * Crash Detection
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|  * The CrashMonitor is used to check if the final session state was successfully
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|  * written at shutdown of the last session. If we did not reach
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|  * 'sessionstore-final-state-write-complete', then it's assumed that the browser
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|  * has previously crashed and we should restore the session.
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|  *
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|  * Forced Restarts
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|  * In the event that a restart is required due to application update or extension
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|  * installation, set the browser.sessionstore.resume_session_once pref to true,
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|  * and the session will be restored the next time the browser starts.
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|  *
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|  * Always Resume
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|  * This service will always resume the session if the integer pref
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|  * browser.startup.page is set to 3.
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|  */
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| 
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| /* :::::::: Constants and Helpers ::::::::::::::: */
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| 
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| const lazy = {};
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| import { AppConstants } from "resource://gre/modules/AppConstants.sys.mjs";
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| 
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| ChromeUtils.defineESModuleGetters(lazy, {
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|   CrashMonitor: "resource://gre/modules/CrashMonitor.sys.mjs",
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|   PrivateBrowsingUtils: "resource://gre/modules/PrivateBrowsingUtils.sys.mjs",
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|   SessionFile: "resource:///modules/sessionstore/SessionFile.sys.mjs",
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|   StartupPerformance:
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|     "resource:///modules/sessionstore/StartupPerformance.sys.mjs",
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|   sessionStoreLogger: "resource:///modules/sessionstore/SessionLogger.sys.mjs",
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| });
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| 
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| const STATE_RUNNING_STR = "running";
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| 
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| const TYPE_NO_SESSION = 0;
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| const TYPE_RECOVER_SESSION = 1;
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| const TYPE_RESUME_SESSION = 2;
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| const TYPE_DEFER_SESSION = 3;
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| 
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| // 'browser.startup.page' preference value to resume the previous session.
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| const BROWSER_STARTUP_RESUME_SESSION = 3;
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| 
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| var gOnceInitializedDeferred = Promise.withResolvers();
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| 
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| /* :::::::: The Service ::::::::::::::: */
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| 
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| export var SessionStartup = {
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|   NO_SESSION: TYPE_NO_SESSION,
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|   RECOVER_SESSION: TYPE_RECOVER_SESSION,
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|   RESUME_SESSION: TYPE_RESUME_SESSION,
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|   DEFER_SESSION: TYPE_DEFER_SESSION,
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| 
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|   // The state to restore at startup.
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|   _initialState: null,
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|   _sessionType: null,
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|   _initialized: false,
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| 
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|   // Stores whether the previous session crashed.
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|   _previousSessionCrashed: null,
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| 
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|   _resumeSessionEnabled: null,
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| 
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|   /* ........ Global Event Handlers .............. */
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| 
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|   /**
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|    * Initialize the component
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|    */
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|   init() {
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|     Services.obs.notifyObservers(null, "sessionstore-init-started");
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| 
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|     if (!AppConstants.DEBUG) {
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|       lazy.StartupPerformance.init();
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|     }
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| 
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|     // do not need to initialize anything in auto-started private browsing sessions
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|     if (lazy.PrivateBrowsingUtils.permanentPrivateBrowsing) {
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|       this._initialized = true;
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|       gOnceInitializedDeferred.resolve();
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|       return;
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|     }
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| 
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|     if (
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|       Services.prefs.getBoolPref(
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|         "browser.sessionstore.resuming_after_os_restart"
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|       )
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|     ) {
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|       lazy.sessionStoreLogger.debug("resuming_after_os_restart");
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|       if (!Services.appinfo.restartedByOS) {
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|         // We had set resume_session_once in order to resume after an OS restart,
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|         // but we aren't automatically started by the OS (or else appinfo.restartedByOS
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|         // would have been set). Therefore we should clear resume_session_once
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|         // to avoid forcing a resume for a normal startup.
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|         Services.prefs.setBoolPref(
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|           "browser.sessionstore.resume_session_once",
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|           false
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|         );
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|       }
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|       Services.prefs.setBoolPref(
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|         "browser.sessionstore.resuming_after_os_restart",
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|         false
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|       );
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|     }
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| 
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|     lazy.SessionFile.read().then(
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|       result => {
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|         lazy.sessionStoreLogger.debug(
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|           `Completed SessionFile.read() with result.origin: ${result.origin}`
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|         );
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|         return this._onSessionFileRead(result);
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|       },
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|       err => {
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|         // SessionFile.read catches most expected failures,
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|         // so a promise rejection here should be logged as an error
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|         lazy.sessionStoreLogger.error("Failure from _onSessionFileRead", err);
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|       }
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|     );
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|   },
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| 
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|   // Wrap a string as a nsISupports.
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|   _createSupportsString(data) {
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|     let string = Cc["@mozilla.org/supports-string;1"].createInstance(
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|       Ci.nsISupportsString
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|     );
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|     string.data = data;
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|     return string;
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|   },
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| 
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|   /**
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|    * Complete initialization once the Session File has been read.
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|    *
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|    * @param source The Session State string read from disk.
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|    * @param parsed The object obtained by parsing |source| as JSON.
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|    */
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|   _onSessionFileRead({ source, parsed, noFilesFound }) {
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|     this._initialized = true;
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|     const crashReasons = {
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|       FINAL_STATE_WRITING_INCOMPLETE: "final-state-write-incomplete",
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|       SESSION_STATE_FLAG_MISSING:
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|         "session-state-missing-or-running-at-last-write",
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|     };
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| 
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|     // Let observers modify the state before it is used
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|     let supportsStateString = this._createSupportsString(source);
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|     Services.obs.notifyObservers(
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|       supportsStateString,
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|       "sessionstore-state-read"
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|     );
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|     let stateString = supportsStateString.data;
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| 
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|     if (stateString != source) {
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|       // The session has been modified by an add-on, reparse.
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|       lazy.sessionStoreLogger.debug(
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|         "After sessionstore-state-read, session has been modified"
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|       );
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|       try {
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|         this._initialState = JSON.parse(stateString);
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|       } catch (ex) {
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|         // That's not very good, an add-on has rewritten the initial
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|         // state to something that won't parse.
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|         lazy.sessionStoreLogger.error(
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|           "'sessionstore-state-read' observer rewrote the state to something that won't parse",
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|           ex
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|         );
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|       }
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|     } else {
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|       // No need to reparse
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|       this._initialState = parsed;
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|     }
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| 
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|     if (this._initialState == null) {
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|       // No valid session found.
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|       this._sessionType = this.NO_SESSION;
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|       lazy.sessionStoreLogger.debug("No valid session found");
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|       Services.obs.notifyObservers(null, "sessionstore-state-finalized");
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|       gOnceInitializedDeferred.resolve();
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|       return;
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|     }
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| 
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|     let initialState = this._initialState;
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|     Services.tm.idleDispatchToMainThread(() => {
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|       let pinnedTabCount = initialState.windows.reduce((winAcc, win) => {
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|         return (
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|           winAcc +
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|           win.tabs.reduce((tabAcc, tab) => {
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|             return tabAcc + (tab.pinned ? 1 : 0);
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|           }, 0)
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|         );
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|       }, 0);
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|       lazy.sessionStoreLogger.debug(
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|         `initialState contains ${pinnedTabCount} pinned tabs`
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|       );
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|       Services.telemetry.scalarSetMaximum(
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|         "browser.engagement.max_concurrent_tab_pinned_count",
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|         pinnedTabCount
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|       );
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|     }, 60000);
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| 
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|     let isAutomaticRestoreEnabled = this.isAutomaticRestoreEnabled();
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|     lazy.sessionStoreLogger.debug(
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|       `isAutomaticRestoreEnabled: ${isAutomaticRestoreEnabled}`
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|     );
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|     // If this is a normal restore then throw away any previous session.
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|     if (!isAutomaticRestoreEnabled && this._initialState) {
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|       lazy.sessionStoreLogger.debug(
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|         "Discarding previous session as we have initialState"
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|       );
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|       delete this._initialState.lastSessionState;
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|     }
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| 
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|     let previousSessionCrashedReason = "N/A";
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|     lazy.CrashMonitor.previousCheckpoints.then(checkpoints => {
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|       if (checkpoints) {
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|         // If the previous session finished writing the final state, we'll
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|         // assume there was no crash.
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|         this._previousSessionCrashed =
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|           !checkpoints["sessionstore-final-state-write-complete"];
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|         if (!checkpoints["sessionstore-final-state-write-complete"]) {
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|           previousSessionCrashedReason =
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|             crashReasons.FINAL_STATE_WRITING_INCOMPLETE;
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|         }
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|       } else if (noFilesFound) {
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|         // If the Crash Monitor could not load a checkpoints file it will
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|         // provide null. This could occur on the first run after updating to
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|         // a version including the Crash Monitor, or if the checkpoints file
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|         // was removed, or on first startup with this profile, or after Firefox Reset.
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| 
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|         // There was no checkpoints file and no sessionstore.js or its backups,
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|         // so we will assume that this was a fresh profile.
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|         this._previousSessionCrashed = false;
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|       } else {
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|         // If this is the first run after an update, sessionstore.js should
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|         // still contain the session.state flag to indicate if the session
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|         // crashed. If it is not present, we will assume this was not the first
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|         // run after update and the checkpoints file was somehow corrupted or
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|         // removed by a crash.
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|         //
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|         // If the session.state flag is present, we will fallback to using it
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|         // for crash detection - If the last write of sessionstore.js had it
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|         // set to "running", we crashed.
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|         let stateFlagPresent =
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|           this._initialState.session && this._initialState.session.state;
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| 
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|         this._previousSessionCrashed =
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|           !stateFlagPresent ||
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|           this._initialState.session.state == STATE_RUNNING_STR;
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|         if (
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|           !stateFlagPresent ||
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|           this._initialState.session.state == STATE_RUNNING_STR
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|         ) {
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|           previousSessionCrashedReason =
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|             crashReasons.SESSION_STATE_FLAG_MISSING;
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|         }
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|       }
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| 
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|       // Report shutdown success via telemetry. Shortcoming here are
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|       // being-killed-by-OS-shutdown-logic, shutdown freezing after
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|       // session restore was written, etc.
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|       Services.telemetry
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|         .getHistogramById("SHUTDOWN_OK")
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|         .add(!this._previousSessionCrashed);
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|       Services.telemetry.recordEvent(
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|         "session_restore",
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|         "shutdown_success",
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|         "session_startup",
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|         null,
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|         {
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|           shutdown_ok: this._previousSessionCrashed.toString(),
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|           shutdown_reason: previousSessionCrashedReason,
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|         }
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|       );
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|       lazy.sessionStoreLogger.debug(
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|         `Previous shutdown ok? ${this._previousSessionCrashed}, reason: ${previousSessionCrashedReason}`
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|       );
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| 
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|       Services.obs.addObserver(this, "sessionstore-windows-restored", true);
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| 
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|       if (this.sessionType == this.NO_SESSION) {
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|         lazy.sessionStoreLogger.debug("Will restore no session");
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|         this._initialState = null; // Reset the state.
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|       } else {
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|         Services.obs.addObserver(this, "browser:purge-session-history", true);
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|       }
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| 
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|       // We're ready. Notify everyone else.
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|       Services.obs.notifyObservers(null, "sessionstore-state-finalized");
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| 
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|       gOnceInitializedDeferred.resolve();
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|     });
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|   },
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| 
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|   /**
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|    * Handle notifications
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|    */
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|   observe(subject, topic) {
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|     switch (topic) {
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|       case "sessionstore-windows-restored":
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|         Services.obs.removeObserver(this, "sessionstore-windows-restored");
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|         lazy.sessionStoreLogger.debug(`sessionstore-windows-restored`);
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|         // Free _initialState after nsSessionStore is done with it.
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|         this._initialState = null;
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|         this._didRestore = true;
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|         break;
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|       case "browser:purge-session-history":
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|         Services.obs.removeObserver(this, "browser:purge-session-history");
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|         // Reset all state on sanitization.
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|         this._sessionType = this.NO_SESSION;
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|         break;
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|     }
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|   },
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| 
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|   /* ........ Public API ................*/
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| 
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|   get onceInitialized() {
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|     return gOnceInitializedDeferred.promise;
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|   },
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| 
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|   /**
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|    * Get the session state as a jsval
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|    */
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|   get state() {
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|     return this._initialState;
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|   },
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| 
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|   /**
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|    * Determines whether automatic session restoration is enabled for this
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|    * launch of the browser. This does not include crash restoration. In
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|    * particular, if session restore is configured to restore only in case of
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|    * crash, this method returns false.
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|    * @returns bool
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|    */
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|   isAutomaticRestoreEnabled() {
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|     if (this._resumeSessionEnabled === null) {
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|       this._resumeSessionEnabled =
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|         !lazy.PrivateBrowsingUtils.permanentPrivateBrowsing &&
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|         (Services.prefs.getBoolPref(
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|           "browser.sessionstore.resume_session_once"
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|         ) ||
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|           Services.prefs.getIntPref("browser.startup.page") ==
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|             BROWSER_STARTUP_RESUME_SESSION);
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|     }
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| 
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|     return this._resumeSessionEnabled;
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|   },
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| 
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|   /**
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|    * Determines whether there is a pending session restore.
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|    * @returns bool
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|    */
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|   willRestore() {
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|     return (
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|       this.sessionType == this.RECOVER_SESSION ||
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|       this.sessionType == this.RESUME_SESSION
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|     );
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|   },
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| 
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|   /**
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|    * Determines whether there is a pending session restore and if that will refer
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|    * back to a crash.
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|    * @returns bool
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|    */
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|   willRestoreAsCrashed() {
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|     return this.sessionType == this.RECOVER_SESSION;
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|   },
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| 
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|   /**
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|    * Returns a boolean or a promise that resolves to a boolean, indicating
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|    * whether we will restore a session that ends up replacing the homepage.
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|    * True guarantees that we'll restore a session; false means that we
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|    * /probably/ won't do so.
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|    * The browser uses this to avoid unnecessarily loading the homepage when
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|    * restoring a session.
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|    */
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|   get willOverrideHomepage() {
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|     // If the session file hasn't been read yet and resuming the session isn't
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|     // enabled via prefs, go ahead and load the homepage. We may still replace
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|     // it when recovering from a crash, which we'll only know after reading the
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|     // session file, but waiting for that would delay loading the homepage in
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|     // the non-crash case.
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|     if (!this._initialState && !this.isAutomaticRestoreEnabled()) {
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|       return false;
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|     }
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|     // If we've already restored the session, we won't override again.
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|     if (this._didRestore) {
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|       return false;
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|     }
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| 
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|     return new Promise(resolve => {
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|       this.onceInitialized.then(() => {
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|         // If there are valid windows with not only pinned tabs, signal that we
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|         // will override the default homepage by restoring a session.
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|         resolve(
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|           this.willRestore() &&
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|             this._initialState &&
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|             this._initialState.windows &&
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|             (!this.willRestoreAsCrashed()
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|               ? this._initialState.windows.filter(w => !w._maybeDontRestoreTabs)
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|               : this._initialState.windows
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|             ).some(w => w.tabs.some(t => !t.pinned))
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|         );
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|       });
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|     });
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|   },
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| 
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|   /**
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|    * Get the type of pending session store, if any.
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|    */
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|   get sessionType() {
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|     if (this._sessionType === null) {
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|       let resumeFromCrash = Services.prefs.getBoolPref(
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|         "browser.sessionstore.resume_from_crash"
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|       );
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|       // Set the startup type.
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|       if (this.isAutomaticRestoreEnabled()) {
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|         this._sessionType = this.RESUME_SESSION;
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|       } else if (this._previousSessionCrashed && resumeFromCrash) {
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|         this._sessionType = this.RECOVER_SESSION;
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|       } else if (this._initialState) {
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|         this._sessionType = this.DEFER_SESSION;
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|       } else {
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|         this._sessionType = this.NO_SESSION;
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|       }
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|     }
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| 
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|     return this._sessionType;
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|   },
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| 
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|   /**
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|    * Get whether the previous session crashed.
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|    */
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|   get previousSessionCrashed() {
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|     return this._previousSessionCrashed;
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|   },
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| 
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|   resetForTest() {
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|     this._resumeSessionEnabled = null;
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|     this._sessionType = null;
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|   },
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| 
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|   QueryInterface: ChromeUtils.generateQI([
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|     "nsIObserver",
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|     "nsISupportsWeakReference",
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|   ]),
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| };
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