Revert of Change call-sites now that SkCanvas is not ref-counted

cc/playback/discardable_image_map.cc

 // Copyright 2015 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/playback/discardable_image_map.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <limits>
 
 #include "base/containers/adapters.h"
-#include "base/memory/ptr_util.h"
 #include "cc/base/math_util.h"
 #include "cc/playback/display_item_list.h"
 #include "third_party/skia/include/utils/SkNWayCanvas.h"
 #include "ui/gfx/geometry/rect_conversions.h"
 #include "ui/gfx/skia_util.h"
 
 namespace cc {
 
 SkRect MapRect(const SkMatrix& matrix, const SkRect& src) {
   SkRect dst;
@@ skipping 159 matching lines @@
   const gfx::Size canvas_size_;
   std::vector<SkPaint> saved_paints_;
 };
 
 }  // namespace
 
 DiscardableImageMap::DiscardableImageMap() {}
 
 DiscardableImageMap::~DiscardableImageMap() {}
 
-std::unique_ptr<SkCanvas> DiscardableImageMap::BeginGeneratingMetadata(
+sk_sp<SkCanvas> DiscardableImageMap::BeginGeneratingMetadata(
     const gfx::Size& bounds) {
   DCHECK(all_images_.empty());
-  return base::MakeUnique<DiscardableImagesMetadataCanvas>(
+  return sk_make_sp<DiscardableImagesMetadataCanvas>(
       bounds.width(), bounds.height(), &all_images_);
 }
 
 void DiscardableImageMap::EndGeneratingMetadata() {
   images_rtree_.Build(all_images_,
                       [](const std::pair<DrawImage, gfx::Rect>& image) {
                         return image.second;
                       });
 }
 
@@ skipping 11 matching lines @@
     DiscardableImageMap* image_map,
     const gfx::Size& bounds)
     : image_map_(image_map),
       metadata_canvas_(image_map->BeginGeneratingMetadata(bounds)) {}
 
 DiscardableImageMap::ScopedMetadataGenerator::~ScopedMetadataGenerator() {
   image_map_->EndGeneratingMetadata();
 }
 
 }  // namespace cc