cc: Add a checkerboard trace event instant to picture layer impl.

cc/layers/picture_layer_impl.cc

 // Copyright 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 "cc/layers/picture_layer_impl.h"
 
 #include <algorithm>
 #include <limits>
 
 #include "base/time/time.h"
@@ skipping 233 matching lines @@
     gfx::Rect geometry_rect = iter.geometry_rect();
     gfx::Rect visible_geometry_rect =
         quad_sink->UnoccludedContentRect(geometry_rect, draw_transform());
     if (visible_geometry_rect.IsEmpty())
       continue;
 
     append_quads_data->visible_content_area +=
         visible_geometry_rect.width() * visible_geometry_rect.height();
 
     if (!*iter || !iter->IsReadyToDraw()) {
+      TRACE_EVENT_INSTANT0("cc",

[danakj, 2014/05/09 19:20:14]

This could potentially happen an awful lot during a scroll. Wanna maybe do this
at most once per call to AppendDrawQuads?

[vmpstr, 2014/05/09 19:29:04]

Makes sense. Done.

+                           "PictureLayerImpl::AppendQuads checkerboard",
+                           TRACE_EVENT_SCOPE_THREAD);
+
       if (draw_checkerboard_for_missing_tiles()) {
         scoped_ptr<CheckerboardDrawQuad> quad = CheckerboardDrawQuad::Create();
         SkColor color = DebugColors::DefaultCheckerboardColor();
         quad->SetNew(
             shared_quad_state, geometry_rect, visible_geometry_rect, color);
         quad_sink->Append(quad.PassAs<DrawQuad>());
       } else {
         SkColor color = SafeOpaqueBackgroundColor();
         scoped_ptr<SolidColorDrawQuad> quad = SolidColorDrawQuad::Create();
         quad->SetNew(shared_quad_state,
@@ skipping 1302 matching lines @@
   return iterator_index_ < iterators_.size();
 }
 
 bool PictureLayerImpl::LayerEvictionTileIterator::IsCorrectType(
     PictureLayerTiling::TilingEvictionTileIterator* it) const {
   return it->get_type() == iteration_stage_ &&
          (**it)->required_for_activation() == required_for_activation_;
 }
 
 }  // namespace cc