Fire NOTIFICATION_EXTENSION_HOST_CREATED at most once per ExtensionHost.

Tests assume that NOTIFICATION_EXTENSION_HOST_CREATED fires at most once
(see BrowserActionInteractiveTest::TearDownOnMainThread which compares
the number of "created" vs "destroyed" notifications).  This assumption
has not been met by the product code, which would fire
NOTIFICATION_EXTENSION_HOST_CREATED for every RenderViewReady
notification which happens not only for the very first RenderViewHost,
but also for possible subsequent RenderViewHost swaps (e.g. when
navigating cross-site).

This CL fixes ExtensionHost::RenderViewReady, to ensure that the
NOTIFICATION_EXTENSION_HOST_CREATED fires at most once per ExtensionHost
object.

Note that NOTIFICATION_EXTENSION_HOST_CREATED is only listened to by
test code (browser_action_interactive_test.cc and
management_api_browsertest.cc).  This means that this CL should have no
effect on production code and product behavior.

Fixed: 1066287
Change-Id: I30b26294c9edb18420b7d3d4b8d560c360914a06
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2129230
Commit-Queue: Łukasz Anforowicz <lukasza@chromium.org>
Reviewed-by: Karan Bhatia <karandeepb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#755504}

chrome/browser/extensions/api/extension_action/browser_action_interactive_test.cc

@@ -886,19 +886,13 @@ IN_PROC_BROWSER_TEST_F(NavigatingExtensionPopupInteractiveTest,
 
 // Tests that an extension pop-up cannot be navigated to a page
 // in another extension.
-//
-// TODO(lukasza): https://crbug.com/1066287: Enable the two tests below after
-// fixing ExtensionHost to ensure that NOTIFICATION_EXTENSION_HOST_CREATED fires
-// at most once - otherwise the test assertion below would fail in
-// TearDownOnMainThread:
-//    EXPECT_EQ(host_watcher_->created(), host_watcher_->destroyed());
 IN_PROC_BROWSER_TEST_F(NavigatingExtensionPopupInteractiveTest,
-                       DISABLED_PageInOtherExtension_Get) {
+                       PageInOtherExtension_Get) {
   GURL other_extension_url = other_extension().GetResourceURL("other.html");
   TestPopupNavigationViaGet(other_extension_url, EXPECTING_NAVIGATION_FAILURE);
 }
 IN_PROC_BROWSER_TEST_F(NavigatingExtensionPopupInteractiveTest,
-                       DISABLED_PageInOtherExtension_Post) {
+                       PageInOtherExtension_Post) {
   GURL other_extension_url = other_extension().GetResourceURL("other.html");
   TestPopupNavigationViaPost(other_extension_url, EXPECTING_NAVIGATION_FAILURE);
 }

extensions/browser/extension_host.cc

@@ -416,6 +416,10 @@ void ExtensionHost::AddNewContents(WebContents* source,
 }
 
 void ExtensionHost::RenderViewReady() {
+  if (has_creation_notification_already_fired_)
+    return;
+  has_creation_notification_already_fired_ = true;
+
   content::NotificationService::current()->Notify(
       extensions::NOTIFICATION_EXTENSION_HOST_CREATED,
       content::Source<BrowserContext>(browser_context_),

extensions/browser/extension_host.h

@@ -186,6 +186,12 @@ class ExtensionHost : public DeferredStartRenderHost,
   // Whether CreateRenderViewNow was called before the extension was ready.
   bool is_render_view_creation_pending_;
 
+  // Whether NOTIFICATION_EXTENSION_HOST_CREATED has been already delivered
+  // (since it is triggered by RenderViewReady which happens not only for the
+  // very first RenderViewHost, but also can happen when swapping RenderViewHost
+  // for another one).
+  bool has_creation_notification_already_fired_ = false;
+
   // Whether the ExtensionHost has finished loading some content at least once.
   // There may be subsequent loads - such as reloads and navigations - and this
   // will not affect its value (it will remain true).