Add impl/comp scrolling instrumentation.

content/renderer/gpu/render_widget_compositor.cc

 // Copyright (c) 2013 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/renderer/gpu/render_widget_compositor.h"
 
 #include <limits>
 #include <string>
 
 #include "base/command_line.h"
@@ skipping 516 matching lines @@
 void RenderWidgetCompositor::Animate(double frame_begin_time) {
   widget_->webwidget()->animate(frame_begin_time);
 }
 
 void RenderWidgetCompositor::Layout() {
   widget_->webwidget()->layout();
 }
 
 void RenderWidgetCompositor::ApplyScrollAndScale(gfx::Vector2d scroll_delta,
                                                  float page_scale) {
+  TRACE_EVENT0("impl-scroll",
+               "RenderWidgetCompositor::ApplyScrollAndScale");

[enne (OOO), 2013/07/29 17:46:31]

Does the other apply scroll and scale trace not cover this?

   widget_->webwidget()->applyScrollAndScale(scroll_delta, page_scale);
 }
 
 scoped_ptr<cc::OutputSurface> RenderWidgetCompositor::CreateOutputSurface() {
   return widget_->CreateOutputSurface();
 }
 
 void RenderWidgetCompositor::DidInitializeOutputSurface(bool success) {
   if (!success)
     widget_->webwidget()->didExitCompositingMode();
@@ skipping 26 matching lines @@
   return RenderThreadImpl::current()->OffscreenContextProviderForMainThread();
 }
 
 scoped_refptr<cc::ContextProvider>
 RenderWidgetCompositor::OffscreenContextProviderForCompositorThread() {
   return RenderThreadImpl::current()->
       OffscreenContextProviderForCompositorThread();
 }
 
 }  // namespace content