Add flag to beginRecording to request saveLayer information

cc/resources/gpu_raster_worker_pool.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/resources/gpu_raster_worker_pool.h"
 
 #include <algorithm>
 
 #include "base/debug/trace_event.h"
 #include "cc/output/context_provider.h"
@@ skipping 30 matching lines @@
     bool use_distance_field_text =
         use_distance_field_text_ ||
         raster_source->ShouldAttemptToUseDistanceFieldText();
     SkSurface* sk_surface = lock_.GetSkSurface(use_distance_field_text);
 
     if (!sk_surface)
       return;
 
     SkPictureRecorder recorder;
     gfx::Size size = resource_->size();
+    const int flags = SkPictureRecorder::kComputeSaveLayerInfo_RecordFlag;
     skia::RefPtr<SkCanvas> canvas =
-        skia::SharePtr(recorder.beginRecording(size.width(), size.height()));
+        skia::SharePtr(recorder.beginRecording(size.width(), size.height(),
+                                               NULL, flags));
+
 
     canvas->save();
     raster_source->PlaybackToCanvas(canvas.get(), rect, scale);
     canvas->restore();
 
     // Add the canvas and recorded picture to |multi_picture_draw_|.
     skia::RefPtr<SkPicture> picture = skia::AdoptRef(recorder.endRecording());
     multi_picture_draw_->add(sk_surface->getCanvas(), picture.get());
   }
 
@@ skipping 180 matching lines @@
 
   ScopedGpuRaster gpu_raster(context_provider_);
   task_graph_runner_->RunUntilIdle();
 
   // Draw each all of the pictures that were collected.  This will also clear
   // the pictures and canvases added to |multi_picture_draw_|
   multi_picture_draw_.draw();
 }
 
 }  // namespace cc