Forward handling of low-mem message to the content renderer client. Add APIs to handle this case.

content/renderer/render_thread.h

 // Copyright (c) 2011 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.
 
 #ifndef CONTENT_RENDERER_RENDER_THREAD_H_
 #define CONTENT_RENDERER_RENDER_THREAD_H_
 #pragma once
 
 #include <set>
 #include <string>
@@ skipping 228 matching lines @@
   virtual bool OnControlMessageReceived(const IPC::Message& msg);
 
   void Init();
 
   void OnSetZoomLevelForCurrentURL(const GURL& url, double zoom_level);
   void OnDOMStorageEvent(const DOMStorageMsg_Event_Params& params);
   void OnSetNextPageID(int32 next_page_id);
   void OnSetCSSColors(const std::vector<CSSColors::CSSColorMapping>& colors);
   void OnCreateNewView(const ViewMsg_New_Params& params);
   void OnTransferBitmap(const SkBitmap& bitmap, int resource_id);
+  void OnPurgeMemory();
   void OnPurgePluginListCache(bool reload_pages);
   void OnNetworkStateChanged(bool online);
   void OnGetAccessibilityTree();
 
   // We initialize WebKit as late as possible.
   void EnsureWebKitInitialized();
 
   // These objects live solely on the render thread.
   scoped_ptr<ScopedRunnableMethodFactory<RenderThread> > task_factory_;
   scoped_ptr<AppCacheDispatcher> appcache_dispatcher_;
@@ skipping 38 matching lines @@
 
   // Map of registered v8 extensions. The key is the extension name.
   std::set<std::string> v8_extensions_;
 
   ObserverList<RenderProcessObserver> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderThread);
 };
 
 #endif  // CONTENT_RENDERER_RENDER_THREAD_H_