cc: Trace the viewport size changing.

cc/trees/layer_tree_host_impl.cc

 // Copyright 2011 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 "cc/trees/layer_tree_host_impl.h"
 
 #include <algorithm>
 #include <limits>
 
 #include "base/basictypes.h"
@@ skipping 2180 matching lines @@
   CreateAndSetRenderer();
   EnforceZeroBudget(true);
   CreateAndSetTileManager();
 
   client_->SetNeedsCommitOnImplThread();
 }
 
 void LayerTreeHostImpl::SetViewportSize(const gfx::Size& device_viewport_size) {
   if (device_viewport_size == device_viewport_size_)
     return;
+  TRACE_EVENT_INSTANT2("cc", "LayerTreeHostImpl::SetViewportSize",
+                       TRACE_EVENT_SCOPE_THREAD, "width",
+                       device_viewport_size.width(), "height",
+                       device_viewport_size.height());
 
   if (pending_tree_)
     active_tree_->SetViewportSizeInvalid();
 
   device_viewport_size_ = device_viewport_size;
 
   UpdateViewportContainerSizes();
   client_->OnCanDrawStateChanged(CanDraw());
   SetFullRootLayerDamage();
   active_tree_->set_needs_update_draw_properties();
@@ skipping 1268 matching lines @@
 }
 
 void LayerTreeHostImpl::UnregisterPictureLayerImpl(PictureLayerImpl* layer) {
   std::vector<PictureLayerImpl*>::iterator it =
       std::find(picture_layers_.begin(), picture_layers_.end(), layer);
   DCHECK(it != picture_layers_.end());
   picture_layers_.erase(it);
 }
 
 }  // namespace cc