Adding tracing to measure synthetic smooth scrolling correctness

content/browser/renderer_host/render_widget_host_view_base.cc

 // 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.
 
 #include "content/browser/renderer_host/render_widget_host_view_base.h"
 
+#include "base/debug/trace_event.h"
 #include "base/logging.h"
 #include "content/browser/accessibility/browser_accessibility_manager.h"
 #include "content/browser/renderer_host/render_widget_host_impl.h"
 #include "content/port/browser/smooth_scroll_gesture.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebScreenInfo.h"
 #include "ui/gfx/display.h"
 #include "ui/gfx/screen.h"
 
 #if defined(OS_WIN)
 #include "base/command_line.h"
@@ skipping 436 matching lines @@
     event.globalX = 0;
     event.globalY = 0;
     event.x = mouse_event_x_;
     event.y = mouse_event_y_;
     event.windowX = event.x;
     event.windowY = event.y;
     host->ForwardWheelEvent(event);
 
     pixels_scrolled_ += abs(event.deltaY);
 
+    TRACE_COUNTER_ID1("gpu", "smooth_scroll_by_pixels_scrolled", this,
+                      pixels_scrolled_);
+
     return true;
   }
 
  private:
   virtual ~BasicMouseWheelSmoothScrollGesture() { }
   bool scroll_down_;
   int pixels_scrolled_;
   int pixels_to_scroll_;
   int mouse_event_x_;
   int mouse_event_y_;
 };
 
 SmoothScrollGesture* RenderWidgetHostViewBase::CreateSmoothScrollGesture(
     bool scroll_down, int pixels_to_scroll, int mouse_event_x,
     int mouse_event_y) {
   return new BasicMouseWheelSmoothScrollGesture(scroll_down, pixels_to_scroll,
                                                 mouse_event_x, mouse_event_y);
 }
 
 void RenderWidgetHostViewBase::ProcessAckedTouchEvent(
     const WebKit::WebTouchEvent& touch,
     bool processed) {
 }
 
 }  // namespace content