Add zoom extension API

chrome/renderer/render_view.h

Index: chrome/renderer/render_view.h
diff --git a/chrome/renderer/render_view.h b/chrome/renderer/render_view.h
index 4ffaea92d4bbaa04fcab6c486557422441b1a12d..eff620e262e817dffbdb67b0c6a1f7133b6a15f3 100644
--- a/chrome/renderer/render_view.h
+++ b/chrome/renderer/render_view.h
@@ -380,6 +380,9 @@ class RenderView : public RenderWidget,
   void RegisterPluginDelegate(WebPluginDelegateProxy* delegate);
   void UnregisterPluginDelegate(WebPluginDelegateProxy* delegate);
 
+  // Respond to a zoom request from the browser process
+  void zoomLevelChanged(int request_id);
+
   // IPC::Channel::Listener implementation -------------------------------------
 
   virtual bool OnMessageReceived(const IPC::Message& msg);
@@ -938,7 +941,7 @@ class RenderView : public RenderWidget,
 #if defined(OS_MACOSX)
   void OnSetWindowVisibility(bool visible);
 #endif
-  void OnSetZoomLevel(double zoom_level);
+  void OnSetZoomLevel(int request_id, double zoom_level);
   void OnSetZoomLevelForLoadingURL(const GURL& url, double zoom_level);
   void OnShouldClose();
   void OnStop();