Change LayerImpl::LayerTreeAsJson to return a std::unique_ptr.

cc/layers/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/layer_impl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 479 matching lines @@
 
 gfx::Vector2dF LayerImpl::FixedContainerSizeDelta() const {
   LayerImpl* scroll_clip_layer =
       layer_tree_impl()->LayerById(scroll_clip_layer_id_);
   if (!scroll_clip_layer)
     return gfx::Vector2dF();
 
   return scroll_clip_layer->bounds_delta();
 }
 
-base::DictionaryValue* LayerImpl::LayerTreeAsJson() const {
-  base::DictionaryValue* result = new base::DictionaryValue;
+std::unique_ptr<base::DictionaryValue> LayerImpl::LayerTreeAsJson() const {
+  std::unique_ptr<base::DictionaryValue> result(new base::DictionaryValue);
   result->SetInteger("LayerId", id());
   result->SetString("LayerType", LayerTypeAsString());
 
   base::ListValue* list = new base::ListValue;
   list->AppendInteger(bounds().width());
   list->AppendInteger(bounds().height());
   result->Set("Bounds", list);
 
   list = new base::ListValue;
   list->AppendDouble(position_.x());
@@ skipping 883 matching lines @@
            .layer_transforms_should_scale_layer_contents) {
     return default_scale;
   }
 
   gfx::Vector2dF transform_scales = MathUtil::ComputeTransform2dScaleComponents(
       ScreenSpaceTransform(), default_scale);
   return std::max(transform_scales.x(), transform_scales.y());
 }
 
 }  // namespace cc