Refactor Extension initialization logic. Add tracing and additional histogram.

chrome/browser/background/background_contents_service.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/background/background_contents_service.h"
 
 #include "apps/app_load_service.h"
 #include "base/basictypes.h"
 #include "base/bind.h"
 #include "base/command_line.h"
@@ skipping 324 matching lines @@
                  content::Source<Profile>(profile));
 
   // Listen for extension uninstall, load, unloaded notification.
   extension_registry_observer_.Add(extensions::ExtensionRegistry::Get(profile));
 }
 
 void BackgroundContentsService::Observe(
     int type,
     const content::NotificationSource& source,
     const content::NotificationDetails& details) {
+  TRACE_EVENT0("browser,startup", "BackgroundContentsService::Observe");
   switch (type) {
     case extensions::NOTIFICATION_EXTENSIONS_READY_DEPRECATED: {
-      const base::TimeTicks start_time = base::TimeTicks::Now();
+      SCOPED_UMA_HISTOGRAM_TIMER(
+          "Extensions.BackgroundContentsServiceStartupTime");
       Profile* profile = content::Source<Profile>(source).ptr();
       LoadBackgroundContentsFromManifests(profile);
       LoadBackgroundContentsFromPrefs(profile);
       SendChangeNotification(profile);
-      UMA_HISTOGRAM_TIMES("Extensions.BackgroundContentsServiceStartupTime",
-                          base::TimeTicks::Now() - start_time);
       break;
     }
     case chrome::NOTIFICATION_BACKGROUND_CONTENTS_DELETED:
       BackgroundContentsShutdown(
           content::Details<BackgroundContents>(details).ptr());
       SendChangeNotification(content::Source<Profile>(source).ptr());
       break;
     case chrome::NOTIFICATION_BACKGROUND_CONTENTS_CLOSED:
       DCHECK(IsTracked(content::Details<BackgroundContents>(details).ptr()));
       UnregisterBackgroundContents(
@@ skipping 408 matching lines @@
     bool user_gesture,
     bool* was_blocked) {
   Browser* browser = chrome::FindLastActiveWithProfile(
       Profile::FromBrowserContext(new_contents->GetBrowserContext()),
       chrome::GetActiveDesktop());
   if (browser) {
     chrome::AddWebContents(browser, NULL, new_contents, disposition,
                            initial_rect, user_gesture, was_blocked);
   }
 }