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

chrome/browser/ui/browser.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 CHROME_BROWSER_UI_BROWSER_H_
 #define CHROME_BROWSER_UI_BROWSER_H_
 #pragma once
 
 #include <map>
 #include <set>
@@ skipping 945 matching lines @@
   virtual void DidNavigateToPendingEntry(TabContents* tab) OVERRIDE;
   virtual content::JavaScriptDialogCreator*
   GetJavaScriptDialogCreator() OVERRIDE;
   virtual void RunFileChooser(
       TabContents* tab,
       const ViewHostMsg_RunFileChooser_Params& params) OVERRIDE;
   virtual void EnumerateDirectory(TabContents* tab, int request_id,
                                 const FilePath& path) OVERRIDE;
   virtual void ToggleFullscreenModeForTab(TabContents* tab,
       bool enter_fullscreen) OVERRIDE;
+  virtual bool IsFullscreenForTab(const TabContents* tab) const OVERRIDE;
   virtual void JSOutOfMemory(TabContents* tab) OVERRIDE;
   virtual void RegisterProtocolHandler(TabContents* tab,
                                        const std::string& protocol,
                                        const GURL& url,
                                        const string16& title) OVERRIDE;
   virtual void RegisterIntentHandler(TabContents* tab,
                                      const string16& action,
                                      const string16& type,
                                      const string16& href,
                                      const string16& title) OVERRIDE;
@@ skipping 441 matching lines @@
   // True if the current tab entered fullscreen mode via webkitRequestFullScreen
   bool tab_caused_fullscreen_;
 
   // True if the browser window has been shown at least once.
   bool window_has_shown_;
 
   DISALLOW_COPY_AND_ASSIGN(Browser);
 };
 
 #endif  // CHROME_BROWSER_UI_BROWSER_H_