Added UMA to track ExtensionService::Init time.

chrome/browser/extensions/extension_service.cc

 // Copyright (c) 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 "chrome/browser/extensions/extension_service.h"
 
 #include <algorithm>
 #include <iterator>
 #include <set>
 
@@ skipping 490 matching lines @@
     const Extension* extension = blacklisted_extensions_.GetByID(lowercase_id);
     if (extension)
       return extension;
   }
   return NULL;
 }
 
 void ExtensionService::Init() {
   CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
+  base::Time begin_time = base::Time::Now();
+
   DCHECK(!is_ready());  // Can't redo init.
   DCHECK_EQ(extensions_.size(), 0u);
 
   const CommandLine* cmd_line = CommandLine::ForCurrentProcess();
   if (cmd_line->HasSwitch(switches::kInstallFromWebstore) ||
       cmd_line->HasSwitch(switches::kLimitedInstallFromWebstore)) {
     // The sole purpose of this launch is to install a new extension from CWS
     // and immediately terminate: loading already installed extensions is
     // unnecessary and may interfere with the inline install dialog (e.g. if an
     // extension listens to onStartup and opens a window).
@@ skipping 59 matching lines @@
         base::Bind(&ExtensionService::GarbageCollectExtensions, AsWeakPtr()),
         base::TimeDelta::FromSeconds(kGarbageCollectStartupDelay));
 
     if (extension_prefs_->NeedsStorageGarbageCollection()) {
       GarbageCollectIsolatedStorage();
       extension_prefs_->SetNeedsStorageGarbageCollection(false);
     }
     system_->management_policy()->RegisterProvider(
         shared_module_policy_provider_.get());
   }
+
+  UMA_HISTOGRAM_TIMES("Extensions.ExtensionServiceInit",

[koz (OOO until 15th September), 2013/11/14 03:41:24]

It's common to have a Time suffix if you are measuring the duration of
something.

+                      base::Time::Now() - begin_time);
 }
 
 bool ExtensionService::UpdateExtension(const std::string& id,
                                        const base::FilePath& extension_path,
                                        const GURL& download_url,
                                        CrxInstaller** out_crx_installer) {
   CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   if (browser_terminating_) {
     LOG(WARNING) << "Skipping UpdateExtension due to browser shutdown";
     // Leak the temp file at extension_path. We don't want to add to the disk
@@ skipping 2214 matching lines @@
 }
 
 void ExtensionService::AddUpdateObserver(extensions::UpdateObserver* observer) {
   update_observers_.AddObserver(observer);
 }
 
 void ExtensionService::RemoveUpdateObserver(
     extensions::UpdateObserver* observer) {
   update_observers_.RemoveObserver(observer);
 }