forked from mirrors/gecko-dev
		
	
		
			
				
	
	
		
			44 lines
		
	
	
	
		
			1.5 KiB
		
	
	
	
		
			JavaScript
		
	
	
	
	
	
			
		
		
	
	
			44 lines
		
	
	
	
		
			1.5 KiB
		
	
	
	
		
			JavaScript
		
	
	
	
	
	
| /* Any copyright is dedicated to the Public Domain.
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|    http://creativecommons.org/publicdomain/zero/1.0/ */
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| 
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| "use strict";
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| 
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| /**
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|  * WHOA THERE: We should never be adding new things to EXPECTED_REFLOWS. This
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|  * is a whitelist that should slowly go away as we improve the performance of
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|  * the front-end. Instead of adding more reflows to the whitelist, you should
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|  * be modifying your code to avoid the reflow.
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|  *
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|  * See https://developer.mozilla.org/en-US/Firefox/Performance_best_practices_for_Firefox_fe_engineers
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|  * for tips on how to do that.
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|  */
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| const EXPECTED_REFLOWS = [
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|   // selection change notification may cause querying the focused editor content
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|   // by IME and that will cause reflow.
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|   {
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|     stack: [
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|       "select@chrome://global/content/bindings/textbox.xml",
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|     ],
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|   }
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| ];
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| 
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| /*
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|  * This test ensures that there are no unexpected
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|  * uninterruptible reflows when opening new tabs.
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|  */
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| add_task(async function() {
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|   await ensureNoPreloadedBrowser();
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| 
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|   // Add a reflow observer and open a new tab.
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|   await withReflowObserver(async function() {
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|     let switchDone = BrowserTestUtils.waitForEvent(window, "TabSwitchDone");
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|     BrowserOpenTab();
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|     await BrowserTestUtils.waitForEvent(gBrowser.selectedTab, "transitionend",
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|         false, e => e.propertyName === "max-width");
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|     await switchDone;
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|   }, EXPECTED_REFLOWS);
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| 
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|   let switchDone = BrowserTestUtils.waitForEvent(window, "TabSwitchDone");
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|   await BrowserTestUtils.removeTab(gBrowser.selectedTab);
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|   await switchDone;
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| });
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