Added UMA collection for fullscreen / mouse lock bubble re-shows.

chrome/browser/ui/exclusive_access/mouse_lock_controller.h

 // Copyright (c) 2015 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_EXCLUSIVE_ACCESS_MOUSE_LOCK_CONTROLLER_H_
 #define CHROME_BROWSER_UI_EXCLUSIVE_ACCESS_MOUSE_LOCK_CONTROLLER_H_
 
 #include "base/macros.h"
 #include "chrome/browser/ui/exclusive_access/exclusive_access_controller_base.h"
 #include "components/content_settings/core/common/content_settings.h"
@@ skipping 41 matching lines @@
     // Mouse lock has been allowed by the user.
     MOUSELOCK_ACCEPTED,
     // Mouse lock has been silently accepted, no notification to user.
     MOUSELOCK_ACCEPTED_SILENTLY
   };
 
   void NotifyMouseLockChange();
 
   void ExitExclusiveAccessIfNecessary() override;
   void NotifyTabExclusiveAccessLost() override;
+  const char* HistogramPrefix() override;
 
   ContentSetting GetMouseLockSetting(const GURL& url) const;
 
   MouseLockState mouse_lock_state_;
 
   bool fake_mouse_lock_for_test_;
 
   DISALLOW_COPY_AND_ASSIGN(MouseLockController);
 };
 
 #endif  //  CHROME_BROWSER_UI_EXCLUSIVE_ACCESS_MOUSE_LOCK_CONTROLLER_H_