Makes GetComponentExtensionResourceManager() thread-safe.

extensions/shell/browser/shell_extensions_browser_client.cc

 // Copyright 2014 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/shell/browser/shell_extensions_browser_client.h"
 
 #include "content/public/browser/browser_thread.h"
 #include "extensions/browser/api/extensions_api_client.h"
 #include "extensions/browser/api/generated_api_registration.h"
 #include "extensions/browser/app_sorting.h"
@@ skipping 157 matching lines @@
   // app_shell-only APIs.
   shell::api::GeneratedFunctionRegistry::RegisterAll(registry);
 }
 
 scoped_ptr<RuntimeAPIDelegate>
 ShellExtensionsBrowserClient::CreateRuntimeAPIDelegate(
     content::BrowserContext* context) const {
   return scoped_ptr<RuntimeAPIDelegate>(new ShellRuntimeAPIDelegate());
 }
 
-ComponentExtensionResourceManager*
+const ComponentExtensionResourceManager*
 ShellExtensionsBrowserClient::GetComponentExtensionResourceManager() {
   return NULL;
 }
 
 void ShellExtensionsBrowserClient::BroadcastEventToRenderers(
     const std::string& event_name,
     scoped_ptr<base::ListValue> args) {
   if (!BrowserThread::CurrentlyOn(BrowserThread::UI)) {
     BrowserThread::PostTask(
         BrowserThread::UI,
@@ skipping 25 matching lines @@
     const std::string& min_version) {
   return true;
 }
 
 void ShellExtensionsBrowserClient::SetAPIClientForTest(
     ExtensionsAPIClient* api_client) {
   api_client_.reset(api_client);
 }
 
 }  // namespace extensions