Add a RWH_TabSwitchPaintDuration histogram.

chrome/browser/renderer_host/render_widget_host_view_gtk.h

 // Copyright (c) 2006-2009 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_GTK_H_
 #define CHROME_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_GTK_H_
 
 #include <gdk/gdk.h>
 
 #include <map>
@@ skipping 102 matching lines @@
   WebCursor current_cursor_;
 
   // Whether we are showing a context menu.
   bool is_showing_context_menu_;
 
   // 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_;
 
+  // The time it took after this view was selected for it to be fully painted.
+  base::TimeTicks tab_switch_paint_time_;
+
   // Variables used only for popups --------------------------------------------
   // Our parent widget.
   RenderWidgetHostView* parent_host_view_;
   // The native view of our parent, equivalent to
   // parent_host_view_->GetNativeView().
   GtkWidget* parent_;
   // We ignore the first mouse release on popups.  This allows the popup to
   // stay open.
   bool is_popup_first_mouse_release_;
 
@@ skipping 10 matching lines @@
 
   // Helper class that lets us allocate plugin containers and move them.
   GtkPluginContainerManager plugin_container_manager_;
 
   // The size that we want the renderer to be.  We keep this in a separate
   // variable because resizing in GTK+ is async.
   gfx::Size requested_size_;
 };
 
 #endif  // CHROME_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_GTK_H_