Added UMA statistics for changing the active window via click or touch events.

ash/wm/panels/panel_layout_manager.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_WM_PANELS_PANEL_LAYOUT_MANAGER_H_
 #define ASH_WM_PANELS_PANEL_LAYOUT_MANAGER_H_
 
 #include <list>
 
 #include "ash/ash_export.h"
@@ skipping 90 matching lines @@
   // Overridden from aura::WindowObserver
   void OnWindowPropertyChanged(aura::Window* window,
                                const void* key,
                                intptr_t old) override;
 
   // Overridden from ash::wm::WindowStateObserver
   void OnPostWindowStateTypeChange(wm::WindowState* window_state,
                                    wm::WindowStateType old_type) override;
 
   // Overridden from aura::client::ActivationChangeObserver
-  void OnWindowActivated(aura::Window* gained_active,
-                         aura::Window* lost_active) override;
+  void OnWindowActivated(
+      aura::client::ActivationChangeObserver::ActivationReason reason,
+      aura::Window* gained_active,
+      aura::Window* lost_active) override;
 
   // Overridden from DisplayController::Observer
   void OnDisplayConfigurationChanged() override;
 
   // Overridden from ShelfLayoutManagerObserver
   void WillChangeVisibilityState(ShelfVisibilityState new_state) override;
 
  private:
   friend class PanelLayoutManagerTest;
   friend class PanelWindowResizerTest;
@@ skipping 68 matching lines @@
   // are currently focused.
   aura::Window* last_active_panel_;
   base::WeakPtrFactory<PanelLayoutManager> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(PanelLayoutManager);
 };
 
 }  // namespace ash
 
 #endif  // ASH_WM_PANELS_PANEL_LAYOUT_MANAGER_H_