Use preferred format to allocate memory for decoded images

cc/tiles/software_image_decode_controller.h

 // Copyright 2016 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.
 
 #ifndef CC_TILES_SOFTWARE_IMAGE_DECODE_CONTROLLER_H_
 #define CC_TILES_SOFTWARE_IMAGE_DECODE_CONTROLLER_H_
 
 #include <stdint.h>
 
 #include <unordered_map>
@@ skipping 78 matching lines @@
   size_t operator()(const ImageDecodeControllerKey& key) const {
     return key.get_hash();
   }
 };
 
 class CC_EXPORT SoftwareImageDecodeController : public ImageDecodeController {
  public:
   using ImageKey = ImageDecodeControllerKey;
   using ImageKeyHash = ImageDecodeControllerKeyHash;
 
-  SoftwareImageDecodeController();
+  explicit SoftwareImageDecodeController(ResourceFormat format = RGBA_8888);
   ~SoftwareImageDecodeController() override;
 
   // ImageDecodeController overrides.
   bool GetTaskForImageAndRef(const DrawImage& image,
                              uint64_t prepare_tiles_id,
                              scoped_refptr<ImageDecodeTask>* task) override;
   void UnrefImage(const DrawImage& image) override;
   DecodedDrawImage GetDecodedImageForDraw(const DrawImage& image) override;
   void DrawWithImageFinished(const DrawImage& image,
                              const DecodedDrawImage& decoded_image) override;
@@ skipping 104 matching lines @@
   ImageMRUCache at_raster_decoded_images_;
   std::unordered_map<ImageKey, int, ImageKeyHash>
       at_raster_decoded_images_ref_counts_;
 
   MemoryBudget locked_images_budget_;
 
   // Note that this is used for cases where the only thing we do is preroll the
   // image the first time we see it. This mimics the previous behavior and
   // should over time change as the compositor starts to handle more cases.
   std::unordered_set<uint32_t> prerolled_images_;
+
+  ResourceFormat format_;
 };
 
 }  // namespace cc
 
 #endif  // CC_TILES_SOFTWARE_IMAGE_DECODE_CONTROLLER_H_