Only allow to lock the mouse when the tab is in fullscreen mode.

content/browser/renderer_host/render_view_host_delegate.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_BROWSER_RENDERER_HOST_RENDER_VIEW_HOST_DELEGATE_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_VIEW_HOST_DELEGATE_H_
 #pragma once
 
 #include <string>
 #include <vector>
@@ skipping 355 matching lines @@
   virtual void HandleMouseUp() {}
   virtual void HandleMouseActivate() {}
 
   // Called when a file selection is to be done.
   virtual void RunFileChooser(
       RenderViewHost* render_view_host,
       const ViewHostMsg_RunFileChooser_Params& params) {}
 
   // Notification that the page wants to go into or out of fullscreen mode.
   virtual void ToggleFullscreenMode(bool enter_fullscreen) {}
+  virtual bool IsFullscreenForCurrentTab() const;
 
   // The contents' preferred size changed.
   virtual void UpdatePreferredSize(const gfx::Size& pref_size) {}
 
   // Notification message from HTML UI.
   virtual void WebUISend(RenderViewHost* render_view_host,
                          const GURL& source_url,
                          const std::string& name,
                          const base::ListValue& args) {}
  protected:
   virtual ~RenderViewHostDelegate() {}
 };
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_VIEW_HOST_DELEGATE_H_