Added the Ash.Tab.TimeBetweenSwitchToExistingTabUserActions histogram to track time between tab swit

ash/shell_delegate.h

 // Copyright (c) 2012 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 ASH_SHELL_DELEGATE_H_
 #define ASH_SHELL_DELEGATE_H_
 
 #include <string>
 
 #include "ash/ash_export.h"
@@ skipping 29 matching lines @@
 namespace ash {
 
 class AccessibilityDelegate;
 class MediaDelegate;
 class NewWindowDelegate;
 class SessionStateDelegate;
 class ShelfDelegate;
 class ShelfItemDelegate;
 class ShelfModel;
 class SystemTrayDelegate;
+class UserMetricsRecorderProxy;
 class UserWallpaperDelegate;
 struct ShelfItem;
 
 class ASH_EXPORT VirtualKeyboardStateObserver {
  public:
   // Called when keyboard is activated/deactivated.
   virtual void OnVirtualKeyboardStateChanged(bool activated) {}
 
  protected:
   virtual ~VirtualKeyboardStateObserver() {}
@@ skipping 86 matching lines @@
   // When a ContextMenu is used for an item created by ShelfWindowWatcher,
   // passes its ShelfItemDelegate and ShelfItem.
   virtual ui::MenuModel* CreateContextMenu(
       aura::Window* root_window,
       ash::ShelfItemDelegate* item_delegate,
       ash::ShelfItem* item) = 0;
 
   // Creates a GPU support object. Shell takes ownership of the object.
   virtual GPUSupport* CreateGPUSupport() = 0;
 
+  // TODO(bruthig):
+  virtual UserMetricsRecorderProxy* CreateUserMetricsRecorderProxy() = 0;
+
   // Get the product name.
   virtual base::string16 GetProductName() const = 0;
 };
 
 }  // namespace ash
 
 #endif  // ASH_SHELL_DELEGATE_H_