ExtensionService: Delay non-critical IO until after startup has finished.

chrome/browser/extensions/extension_service.cc

Index: chrome/browser/extensions/extension_service.cc
diff --git a/chrome/browser/extensions/extension_service.cc b/chrome/browser/extensions/extension_service.cc
index 970873359b1de7408e5fc92521563b1eb7e3f9ac..0dda2283b2afec85ec8a0f8db813508772e7373e 100644
--- a/chrome/browser/extensions/extension_service.cc
+++ b/chrome/browser/extensions/extension_service.cc
@@ -372,6 +372,7 @@ ExtensionService::ExtensionService(Profile* profile,
       show_extensions_prompts_(true),
       install_updates_when_idle_(true),
       ready_(false),
+      external_update_check_has_run_(false),
       toolbar_model_(ALLOW_THIS_IN_INITIALIZER_LIST(this)),
       menu_manager_(profile),
       app_notification_manager_(
@@ -614,12 +615,22 @@ void ExtensionService::Init() {
         g_browser_process->profile_manager()->will_import()) {
       RegisterForImportFinished();
     } else {
-      // TODO(erikkay) this should probably be deferred to a future point
-      // rather than running immediately at startup.
-      CheckForExternalUpdates();
-
-      // TODO(erikkay) this should probably be deferred as well.
-      GarbageCollectExtensions();
+      // For newly created profiles, check for external updates immediately.
+      // Otherwise delay the check until onload fires for the main frame, to
+      // speed up startup.
+      bool is_new_profile =
+          profile_->GetPrefs()->GetInitializationStatus() ==
+              PrefService::INITIALIZATION_STATUS_CREATED_NEW_PROFILE;
+      if (is_new_profile)
+        CheckForExternalUpdates();
+
+      // Hook onload for the first frame to perform delayed startup actions.
+      // TODO(jeremy):If a generic mechanism is introduced to perform actions
+      // delayed until after startup finishes, use that rather than listening
+      // on the event ourselves.
+      registrar_.Add(this,
+                     content::NOTIFICATION_LOAD_COMPLETED_MAIN_FRAME,
+                     content::NotificationService::AllSources());
     }
   }
 }
@@ -1734,6 +1745,12 @@ void ExtensionService::SetAllowFileAccess(const Extension* extension,
 void ExtensionService::CheckForExternalUpdates() {
   CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
+  // In the case of a new profile, this function is called at init time and then
+  // again when the first frame loads.  Short-circuit subsequent calls.
+  if (external_update_check_has_run_)
+    return;
+  external_update_check_has_run_ = true;
+
   // Note that this installation is intentionally silent (since it didn't
   // go through the front-end).  Extensions that are registered in this
   // way are effectively considered 'pre-bundled', and so implicitly
@@ -2689,6 +2706,16 @@ void ExtensionService::Observe(int type,
               host->extension()));
       break;
     }
+    case content::NOTIFICATION_LOAD_COMPLETED_MAIN_FRAME:
+      registrar_.Remove(
+          this,
+          content::NOTIFICATION_LOAD_COMPLETED_MAIN_FRAME,
+          content::NotificationService::AllSources());
+
+      CheckForExternalUpdates();
+      GarbageCollectExtensions();
+      break;
+
     case content::NOTIFICATION_RENDERER_PROCESS_CREATED: {
       content::RenderProcessHost* process =
           content::Source<content::RenderProcessHost>(source).ptr();