Add WasShown/WasHidden to RenderFrameObserver.

content/public/renderer/render_frame_observer.h

 // 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.
 
 #ifndef CONTENT_PUBLIC_RENDERER_RENDER_FRAME_OBSERVER_H_
 #define CONTENT_PUBLIC_RENDERER_RENDER_FRAME_OBSERVER_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/strings/string16.h"
@@ skipping 21 matching lines @@
   // By default, observers will be deleted when the RenderFrame goes away.  If
   // they want to outlive it, they can override this function.
   virtual void OnDestruct();
 
   // Called when a Pepper plugin is created.
   virtual void DidCreatePepperPlugin(RendererPpapiHost* host) {}
 
   // Called when a load is explicitly stopped by the user or browser.
   virtual void OnStop() {}
 
+  // Called when the RenderFrame visiblity is changed.
+  virtual void WasHidden() {}
+  virtual void WasShown() {}
+
   // These match the Blink API notifications
   virtual void DidCommitProvisionalLoad(bool is_new_navigation) {}
   virtual void DidStartProvisionalLoad() {}
   virtual void DidFailProvisionalLoad(const blink::WebURLError& error) {}
   virtual void DidFinishLoad() {}
   virtual void DidFinishDocumentLoad() {}
   virtual void WillReleaseScriptContext(v8::Handle<v8::Context> context,
                                         int world_id) {}
   virtual void DidClearWindowObject() {}
   virtual void DidChangeName(const base::string16& name) {}
@@ skipping 36 matching lines @@
   RenderFrame* render_frame_;
   // The routing ID of the associated RenderFrame.
   int routing_id_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderFrameObserver);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_RENDERER_RENDER_FRAME_OBSERVER_H_