cc: Add traces for identification of raster buffer.

cc/raster/bitmap_raster_buffer_provider.cc

 // Copyright 2014 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/raster/bitmap_raster_buffer_provider.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 24 matching lines @@
   }
 
   // Overridden from RasterBuffer:
   void Playback(
       const RasterSource* raster_source,
       const gfx::Rect& raster_full_rect,
       const gfx::Rect& raster_dirty_rect,
       uint64_t new_content_id,
       float scale,
       const RasterSource::PlaybackSettings& playback_settings) override {
+    TRACE_EVENT0("cc", "BitmapRasterBuffer::Playback");
     gfx::Rect playback_rect = raster_full_rect;
     if (resource_has_previous_content_) {
       playback_rect.Intersect(raster_dirty_rect);
     }
     DCHECK(!playback_rect.IsEmpty())
         << "Why are we rastering a tile that's not dirty?";
 
     size_t stride = 0u;
     RasterBufferProvider::PlaybackToMemory(
         lock_.sk_bitmap().getPixels(), resource_->format(), resource_->size(),
@@ skipping 48 matching lines @@
 }
 
 bool BitmapRasterBufferProvider::GetResourceRequiresSwizzle(
     bool must_support_alpha) const {
   return ResourceFormatRequiresSwizzle(GetResourceFormat(must_support_alpha));
 }
 
 void BitmapRasterBufferProvider::Shutdown() {}
 
 }  // namespace cc