Refactor Extension initialization logic. Add tracing and additional histogram.

extensions/browser/process_manager.cc

 // Copyright 2013 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 "extensions/browser/process_manager.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/lazy_instance.h"
 #include "base/logging.h"
@@ skipping 735 matching lines @@
 
 // static
 void ProcessManager::SetEventPageSuspendingTimeForTesting(
     unsigned suspending_time_msec) {
   g_event_page_suspending_time_msec = suspending_time_msec;
 }
 
 void ProcessManager::Observe(int type,
                              const content::NotificationSource& source,
                              const content::NotificationDetails& details) {
+  TRACE_EVENT0("browser,startup", "ProcessManager::Observe");
   switch (type) {
     case extensions::NOTIFICATION_EXTENSIONS_READY_DEPRECATED: {
       // TODO(jamescook): Convert this to use ExtensionSystem::ready() instead
       // of a notification.
-      const base::TimeTicks start_time = base::TimeTicks::Now();
+      SCOPED_UMA_HISTOGRAM_TIMER("Extensions.ProcessManagerStartupHostsTime");
       MaybeCreateStartupBackgroundHosts();
-      UMA_HISTOGRAM_TIMES("Extensions.ProcessManagerStartupHostsTime",
-                          base::TimeTicks::Now() - start_time);
       break;
     }
 
     case extensions::NOTIFICATION_EXTENSION_LOADED_DEPRECATED: {
       BrowserContext* context = content::Source<BrowserContext>(source).ptr();
       ExtensionSystem* system = ExtensionSystem::Get(context);
       if (system->ready().is_signaled()) {
         // The extension system is ready, so create the background host.
         const Extension* extension =
             content::Details<const Extension>(details).ptr();
@@ skipping 263 matching lines @@
   if (extension && !IncognitoInfo::IsSplitMode(extension)) {
     BrowserContext* original_context =
         ExtensionsBrowserClient::Get()->GetOriginalContext(GetBrowserContext());
     return ProcessManager::Get(original_context)->GetSiteInstanceForURL(url);
   }
 
   return ProcessManager::GetSiteInstanceForURL(url);
 }
 
 }  // namespace extensions