Use std::unique_ptr to signal ownership transfer in WebCompositorSupport

cc/blink/web_compositor_support_impl.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/blink/web_compositor_support_impl.h"
 
-#include <memory>
+#include <utility>
 
+#include "base/memory/ptr_util.h"
 #include "cc/blink/web_content_layer_impl.h"
 #include "cc/blink/web_display_item_list_impl.h"
 #include "cc/blink/web_external_texture_layer_impl.h"
 #include "cc/blink/web_image_layer_impl.h"
 #include "cc/blink/web_layer_impl.h"
 #include "cc/blink/web_scrollbar_layer_impl.h"
 #include "cc/layers/layer.h"
 #include "cc/output/output_surface.h"
 #include "cc/output/software_output_device.h"
 
 using blink::WebContentLayer;
 using blink::WebContentLayerClient;
 using blink::WebDisplayItemList;
 using blink::WebExternalTextureLayer;
 using blink::WebImageLayer;
 using blink::WebLayer;
 using blink::WebScrollbar;
 using blink::WebScrollbarLayer;
 using blink::WebScrollbarThemeGeometry;
 using blink::WebScrollbarThemePainter;
 
 namespace cc_blink {
 
 WebCompositorSupportImpl::WebCompositorSupportImpl() {
 }
 
 WebCompositorSupportImpl::~WebCompositorSupportImpl() {
 }
 
-WebLayer* WebCompositorSupportImpl::createLayer() {
-  return new WebLayerImpl();
+std::unique_ptr<WebLayer> WebCompositorSupportImpl::createLayer() {
+  return base::MakeUnique<WebLayerImpl>();
 }
 
-WebLayer* WebCompositorSupportImpl::createLayerFromCCLayer(cc::Layer* layer) {
-  return new WebLayerImpl(layer);
+std::unique_ptr<WebLayer> WebCompositorSupportImpl::createLayerFromCCLayer(
+    cc::Layer* layer) {
+  return base::MakeUnique<WebLayerImpl>(layer);
 }
 
-WebContentLayer* WebCompositorSupportImpl::createContentLayer(
+std::unique_ptr<WebContentLayer> WebCompositorSupportImpl::createContentLayer(
     WebContentLayerClient* client) {
-  return new WebContentLayerImpl(client);
+  return base::MakeUnique<WebContentLayerImpl>(client);
 }
 
-WebExternalTextureLayer* WebCompositorSupportImpl::createExternalTextureLayer(
+std::unique_ptr<WebExternalTextureLayer>
+WebCompositorSupportImpl::createExternalTextureLayer(
     cc::TextureLayerClient* client) {
-  return new WebExternalTextureLayerImpl(client);
+  return base::MakeUnique<WebExternalTextureLayerImpl>(client);
 }
 
-blink::WebImageLayer* WebCompositorSupportImpl::createImageLayer() {
-  return new WebImageLayerImpl();
+std::unique_ptr<blink::WebImageLayer>
+WebCompositorSupportImpl::createImageLayer() {
+  return base::MakeUnique<WebImageLayerImpl>();
 }
 
-WebScrollbarLayer* WebCompositorSupportImpl::createScrollbarLayer(
-    WebScrollbar* scrollbar,
+std::unique_ptr<WebScrollbarLayer>
+WebCompositorSupportImpl::createScrollbarLayer(
+    std::unique_ptr<WebScrollbar> scrollbar,
     WebScrollbarThemePainter painter,
-    WebScrollbarThemeGeometry* geometry) {
-  return new WebScrollbarLayerImpl(scrollbar, painter, geometry);
+    std::unique_ptr<WebScrollbarThemeGeometry> geometry) {
+  return base::MakeUnique<WebScrollbarLayerImpl>(std::move(scrollbar), painter,
+                                                 std::move(geometry));
 }
 
-WebScrollbarLayer* WebCompositorSupportImpl::createSolidColorScrollbarLayer(
+std::unique_ptr<WebScrollbarLayer>
+WebCompositorSupportImpl::createSolidColorScrollbarLayer(
     WebScrollbar::Orientation orientation,
     int thumb_thickness,
     int track_start,
     bool is_left_side_vertical_scrollbar) {
-  return new WebScrollbarLayerImpl(orientation,
-                                   thumb_thickness,
-                                   track_start,
-                                   is_left_side_vertical_scrollbar);
+  return base::MakeUnique<WebScrollbarLayerImpl>(
+      orientation, thumb_thickness, track_start,
+      is_left_side_vertical_scrollbar);
 }
 
 }  // namespace cc_blink