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

cc/layers/nine_patch_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/nine_patch_layer_impl.h"
 
 #include "base/strings/stringprintf.h"
 #include "base/values.h"
 #include "cc/base/math_util.h"
 #include "cc/quads/texture_draw_quad.h"
@@ skipping 332 matching lines @@
                    vertex_opacity, flipped, nearest_neighbor_, false);
       ValidateQuadResources(quad);
     }
   }
 }
 
 const char* NinePatchLayerImpl::LayerTypeAsString() const {
   return "cc::NinePatchLayerImpl";
 }
 
-base::DictionaryValue* NinePatchLayerImpl::LayerTreeAsJson() const {
-  base::DictionaryValue* result = LayerImpl::LayerTreeAsJson();
+std::unique_ptr<base::DictionaryValue> NinePatchLayerImpl::LayerTreeAsJson()
+    const {
+  std::unique_ptr<base::DictionaryValue> result = LayerImpl::LayerTreeAsJson();
 
   base::ListValue* list = new base::ListValue;
   list->AppendInteger(image_aperture_.origin().x());
   list->AppendInteger(image_aperture_.origin().y());
   list->AppendInteger(image_aperture_.size().width());
   list->AppendInteger(image_aperture_.size().height());
   result->Set("ImageAperture", list);
 
   list = new base::ListValue;
   list->AppendInteger(image_bounds_.width());
   list->AppendInteger(image_bounds_.height());
   result->Set("ImageBounds", list);
 
   result->Set("Border", MathUtil::AsValue(border_).release());
 
   result->SetBoolean("FillCenter", fill_center_);
 
   return result;
 }
 
 }  // namespace cc