[ash-md] Adds UMA items count and selection depth for Alt+Tab

ash/wm/window_cycle_list.h

 // Copyright 2014 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_WM_WINDOW_CYCLE_LIST_H_
 #define ASH_WM_WINDOW_CYCLE_LIST_H_
 
 #include <memory>
 #include <vector>
 
@@ skipping 13 matching lines @@
   using WindowList = std::vector<WmWindow*>;
 
   explicit WindowCycleList(const WindowList& windows);
   ~WindowCycleList() override;
 
   bool empty() const { return windows_.empty(); }
 
   // Cycles to the next or previous window based on |direction|.
   void Step(WindowCycleController::Direction direction);
 
+  int current_index() const { return current_index_; }
+
  private:
   friend class WindowCycleControllerTest;
   const WindowList& windows() const { return windows_; }
 
   // aura::WindowObserver overrides:
   // There is a chance a window is destroyed, for example by JS code. We need to
   // take care of that even if it is not intended for the user to close a window
   // while window cycling.
   void OnWindowDestroying(WmWindow* window) override;
 
   // List of weak pointers to windows to use while cycling with the keyboard.
   // List is built when the user initiates the gesture (i.e. hits alt-tab the
   // first time) and is emptied when the gesture is complete (i.e. releases the
   // alt key).
   WindowList windows_;
 
-  // Current position in the |windows_|
+  // Current position in the |windows_|. Can be used to query selection depth
+  // i.e. position of an active window in a global MRU ordering.

[tdanderson, 2016/06/24 19:25:56]

micro nit: "... query selection depth, i.e., the position ..."

[varkha, 2016/06/24 19:59:46]

Done.

   int current_index_;
 
   // Wrapper for the window brought to the front.
   std::unique_ptr<ScopedShowWindow> showing_window_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowCycleList);
 };
 
 }  // namespace ash
 
 #endif  // ASH_WM_WINDOW_CYCLE_LIST_H_