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 219 matching lines @@
                                 color,
                                 width);
       quad_sink->Append(debug_border_quad.PassAs<DrawQuad>());
     }
   }
 
   // Keep track of the tilings that were used so that tilings that are
   // unused can be considered for removal.
   std::vector<PictureLayerTiling*> seen_tilings;
 
+  bool had_checkerboard_quads = false;
   for (PictureLayerTilingSet::CoverageIterator iter(
       tilings_.get(), contents_scale_x(), rect, ideal_contents_scale_);
        iter;
        ++iter) {
     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()) {
+      had_checkerboard_quads = true;
       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 75 matching lines @@
 
     if (iter->priority(ACTIVE_TREE).resolution != HIGH_RESOLUTION) {
       append_quads_data->approximated_visible_content_area +=
           visible_geometry_rect.width() * visible_geometry_rect.height();
     }
 
     if (seen_tilings.empty() || seen_tilings.back() != iter.CurrentTiling())
       seen_tilings.push_back(iter.CurrentTiling());
   }
 
+  if (had_checkerboard_quads) {
+    TRACE_EVENT_INSTANT0("cc",
+                         "PictureLayerImpl::AppendQuads checkerboard",
+                         TRACE_EVENT_SCOPE_THREAD);
+  }
+
   // Aggressively remove any tilings that are not seen to save memory. Note
   // that this is at the expense of doing cause more frequent re-painting. A
   // better scheme would be to maintain a tighter visible_content_rect for the
   // finer tilings.
   CleanUpTilingsOnActiveLayer(seen_tilings);
 }
 
 void PictureLayerImpl::DidUnregisterLayer() {
   layer_needs_to_register_itself_ = true;
 }
@@ skipping 1207 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