UMA stats for stylus usage

ui/aura/client/aura_constants.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 UI_AURA_CLIENT_AURA_CONSTANTS_H_
 #define UI_AURA_CLIENT_AURA_CONSTANTS_H_
 
 #include "ui/aura/aura_export.h"
 #include "ui/aura/window.h"
 #include "ui/base/ui_base_types.h"
@@ skipping 51 matching lines @@
 // A property key to store ui::WindowShowState for restoring a window.
 // Used in Ash to remember the show state before the window was minimized.
 AURA_EXPORT extern const WindowProperty<ui::WindowShowState>* const
     kRestoreShowStateKey;
 
 // A property key to store ui::WindowShowState for a window.
 // See ui/base/ui_base_types.h for its definition.
 AURA_EXPORT extern const WindowProperty<ui::WindowShowState>* const
     kShowStateKey;
 
+// A property key to store the type of window that will be used to record stylus
+// metrics.
+AURA_EXPORT extern const aura::WindowProperty<int>* const

[xiyuan, 2016/09/12 20:15:47]

This does not feel like need to be here. Can we move this somewhere else, e.g.
in stylus_metrics_recorder.h ? 

[xiaoyinh(OOO Sep 11-29), 2016/09/16 18:41:16]

Done.

+    kStylusWindowTypeBucket;
+
 // The inset of the topmost view in the client view from the top of the
 // non-client view. The topmost view depends on the window type. The topmost
 // view is the tab strip for tabbed browser windows, the toolbar for popups,
 // the web contents for app windows and varies for fullscreen windows.
 AURA_EXPORT extern const aura::WindowProperty<int>* const kTopViewInset;
 
 // A property key to store window icon.
 AURA_EXPORT extern const WindowProperty<gfx::ImageSkia*>* const kWindowIconKey;
 
 // Alphabetical sort.
 
 }  // namespace client
 }  // namespace aura
 
 #endif  // UI_AURA_CLIENT_AURA_CONSTANTS_H_