Bug 1803810 - Part 9: Make ChromeUtils.importESModule compatible with workers. r=jonco

Expose importESModule to worker as well, while only supporting
{ global: "current" } and { global: "contextual" } options.
"contextual" in worker is an alias to "current".

Differential Revision: https://phabricator.services.mozilla.com/D199461

dom/base/ChromeUtils.cpp

@@ -655,6 +655,13 @@ static mozJSModuleLoader* GetModuleLoaderForCurrentGlobal(
   }
 
   if (targetModuleLoader->HasFetchingModules()) {
+    if (!NS_IsMainThread()) {
+      JS_ReportErrorASCII(aCx,
+                          "ChromeUtils.importESModule cannot be used in worker "
+                          "when there is ongoing dynamic import");
+      return nullptr;
+    }
+
     if (!mozilla::SpinEventLoopUntil(
             "importESModule for current global"_ns, [&]() -> bool {
               return !targetModuleLoader->HasFetchingModules();
@@ -685,6 +692,11 @@ static mozJSModuleLoader* GetModuleLoaderForOptions(
       return mozJSModuleLoader::GetOrCreateDevToolsLoader();
 
     case ImportESModuleTargetGlobal::Contextual: {
+      if (!NS_IsMainThread()) {
+        return GetModuleLoaderForCurrentGlobal(aCx, aGlobal,
+                                               aMaybeSyncLoaderScope);
+      }
+
       RefPtr devToolsModuleloader = mozJSModuleLoader::GetDevToolsLoader();
       if (devToolsModuleloader &&
           devToolsModuleloader->IsLoaderGlobal(aGlobal.Get())) {
@@ -704,6 +716,17 @@ static mozJSModuleLoader* GetModuleLoaderForOptions(
 
 static bool ValidateImportOptions(
     JSContext* aCx, const ImportESModuleOptionsDictionary& aOptions) {
+  if (!NS_IsMainThread() &&
+      (!aOptions.mGlobal.WasPassed() ||
+       (aOptions.mGlobal.Value() != ImportESModuleTargetGlobal::Current &&
+        aOptions.mGlobal.Value() != ImportESModuleTargetGlobal::Contextual))) {
+    JS_ReportErrorASCII(aCx,
+                        "ChromeUtils.importESModule: Only { global: "
+                        "\"current\" } and { global: \"contextual\" } options "
+                        "are supported on worker");
+    return false;
+  }
+
   if (aOptions.mGlobal.WasPassed() &&
       aOptions.mLoadInDevToolsLoader.WasPassed()) {
     JS_ReportErrorASCII(aCx,

dom/chrome-webidl/ChromeUtils.webidl

@@ -313,6 +313,25 @@ namespace ChromeUtils {
   [NewObject]
   Promise<sequence<CDMInformation>> getGMPContentDecryptionModuleInformation();
 
+  /**
+   * Synchronously loads and evaluates the JS module source located at
+   * 'aResourceURI'.
+   *
+   * @param aResourceURI A resource:// URI string to load the module from.
+   * @param aOption An option to specify where to load the module into.
+   * @returns the module's namespace object.
+   *
+   * The implementation maintains a hash of aResourceURI->global obj.
+   * Subsequent invocations of import with 'aResourceURI' pointing to
+   * the same file will not cause the module to be re-evaluated.
+   *
+   * In worker threads, aOption is required and only { global: "current" } and
+   * { global: "contextual" } are supported.
+   */
+  [Throws]
+  object importESModule(DOMString aResourceURI,
+                        optional ImportESModuleOptionsDictionary aOptions = {});
+
   /**
    * IF YOU ADD NEW METHODS HERE, MAKE SURE THEY ARE THREAD-SAFE.
    */
@@ -508,22 +527,6 @@ partial namespace ChromeUtils {
   [Throws]
   object import(UTF8String aResourceURI, optional object aTargetObj);
 
-  /**
-   * Synchronously loads and evaluates the JS module source located at
-   * 'aResourceURI'.
-   *
-   * @param aResourceURI A resource:// URI string to load the module from.
-   * @param aOption An option to specify where to load the module into.
-   * @returns the module's namespace object.
-   *
-   * The implementation maintains a hash of aResourceURI->global obj.
-   * Subsequent invocations of import with 'aResourceURI' pointing to
-   * the same file will not cause the module to be re-evaluated.
-   */
-  [Throws]
-  object importESModule(DOMString aResourceURI,
-                        optional ImportESModuleOptionsDictionary aOptions = {});
-
   /**
    * Defines a property on the given target which lazily imports a JavaScript
    * module when accessed.
@@ -1004,6 +1007,7 @@ enum ImportESModuleTargetGlobal {
   /**
    * If the current global is DevTools' distinct system global, load into the
    * DevTools' distinct system global.
+   * If the current thread is worker thread, load into the current global.
    * Otherwise load into the shared system global.
    *
    * This is a temporary workaround until DevTools modules are ESMified.