Add a RWH_TabSwitchPaintDuration histogram.

chrome/browser/renderer_host/render_widget_host_view_mac.mm

 // 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.
 
 #include "chrome/browser/renderer_host/render_widget_host_view_mac.h"
 
 #include "base/histogram.h"
 #import "base/scoped_nsobject.h"
 #include "base/string_util.h"
 #include "base/sys_string_conversions.h"
@@ skipping 100 matching lines @@
 }
 
 RenderWidgetHost* RenderWidgetHostViewMac::GetRenderWidgetHost() const {
   return render_widget_host_;
 }
 
 void RenderWidgetHostViewMac::DidBecomeSelected() {
   if (!is_hidden_)
     return;
 
+  if (tab_switch_paint_time_.is_null())
+    tab_switch_paint_time_ = base::TimeTicks::Now();
   is_hidden_ = false;
   render_widget_host_->WasRestored();
 }
 
 void RenderWidgetHostViewMac::WasHidden() {
   if (is_hidden_)
     return;
 
   // If we receive any more paint messages while we are hidden, we want to
   // ignore them so we don't re-allocate the backing store.  We will paint
@@ skipping 685 matching lines @@
     }
     if (!renderWidgetHostView_->whiteout_start_time_.is_null()) {
       base::TimeDelta whiteout_duration = base::TimeTicks::Now() -
           renderWidgetHostView_->whiteout_start_time_;
       UMA_HISTOGRAM_TIMES("MPArch.RWHH_WhiteoutDuration", whiteout_duration);
 
       // Reset the start time to 0 so that we start recording again the next
       // time the backing store is NULL...
       renderWidgetHostView_->whiteout_start_time_ = base::TimeTicks();
     }
+    if (!renderWidgetHostView_->tab_switch_paint_time_.is_null()) {
+      base::TimeDelta tab_switch_paint_duration = base::TimeTicks::Now() -
+          renderWidgetHostView_->tab_switch_paint_time_;
+      UMA_HISTOGRAM_TIMES("MPArch.RWH_TabSwitchPaintDuration",
+          tab_switch_paint_duration);
+      // Reset tab_switch_paint_time_ to 0 so future tab selections are
+      // recorded.
+      renderWidgetHostView_->tab_switch_paint_time_ = base::TimeTicks();
+    }
   } else {
     [[NSColor whiteColor] set];
     NSRectFill(dirtyRect);
     if (renderWidgetHostView_->whiteout_start_time_.is_null())
       renderWidgetHostView_->whiteout_start_time_ = base::TimeTicks::Now();
   }
 }
 
 - (BOOL)canBecomeKeyView {
   if (!renderWidgetHostView_->render_widget_host_)
@@ skipping 503 matching lines @@
                                  base::Time::Now().ToDoubleT());
     renderWidgetHostView_->render_widget_host_->ForwardKeyboardEvent(event);
   } else {
     renderWidgetHostView_->render_widget_host_->ImeConfirmComposition(
         UTF8ToUTF16([im_text UTF8String]));
   }
   renderWidgetHostView_->im_composing_ = false;
 }
 
 @end