Add a RWH_TabSwitchPaintDuration histogram.

chrome/browser/renderer_host/render_widget_host_view_win.h

 // Copyright (c) 2006-2008 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_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_WIN_H_
 #define CHROME_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_WIN_H_
 
 #include <atlbase.h>
 #include <atlapp.h>
 #include <atlcrack.h>
@@ skipping 272 matching lines @@
   // The time at which this view started displaying white pixels as a result of
   // not having anything to paint (empty backing store from renderer). This
   // value returns true for is_null() if we are not recording whiteout times.
   base::TimeTicks whiteout_start_time_;
 
   // Whether the renderer is made accessible.
   // TODO(jcampan): http://b/issue?id=1432077 This is a temporary work-around
   // until that bug is fixed.
   bool renderer_accessible_;
 
+  // The time it took after this view was selected for it to be fully painted.
+  base::TimeTicks tab_switch_paint_time_;
+
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostViewWin);
 };
 
 #endif  // CHROME_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_WIN_H_