cc: Add scaling for checkered images.

cc/tiles/checker_image_tracker.h

 // Copyright 2017 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_CHECKER_IMAGE_TRACKER_H_
 #define CC_TILES_CHECKER_IMAGE_TRACKER_H_
 
 #include <unordered_map>
 #include <vector>
 
@@ skipping 22 matching lines @@
 // sync tree until the previous tree is activated.
 class CC_EXPORT CheckerImageTracker {
  public:
   CheckerImageTracker(ImageController* image_controller,
                       CheckerImageTrackerClient* client,
                       bool enable_checker_imaging);
   ~CheckerImageTracker();
 
   // Returns true if the decode for |image| will be deferred to the image decode
   // service and it should be be skipped during raster.
-  bool ShouldCheckerImage(const PaintImage& image, WhichTree tree);
+  bool ShouldCheckerImage(const DrawImage& image, WhichTree tree);
 
   using ImageDecodeQueue = std::vector<PaintImage>;
   void ScheduleImageDecodeQueue(ImageDecodeQueue image_decode_queue);
 
   // Returns the set of images to invalidate on the sync tree.
   const PaintImageIdFlatSet& TakeImagesToInvalidateOnSyncTree();
 
   // Called when the sync tree is activated. Each call to
   // TakeImagesToInvalidateOnSyncTree() must be followed by this when the
   // invalidated sync tree is activated.
@@ skipping 10 matching lines @@
     // is always skipped during rasterization of content that includes this
     // image until it has been decoded using the decode service.
     ASYNC,
     // The image has been decoded asynchronously once and should now be
     // synchronously rasterized with the content.
     SYNC_DECODED_ONCE,
     // The image has been permanently vetoed from being decoded async.
     SYNC_PERMANENT,
   };
 
+  // Contains the information to construct a DrawImage from PaintImage when
+  // queuing the image decode.
+  struct DecodeState {
+    DecodePolicy policy = DecodePolicy::SYNC_PERMANENT;
+    SkFilterQuality filter_quality = kNone_SkFilterQuality;
+    SkSize scale;

[ericrk, 2017/06/06 22:39:51]

SkSize has no default constructor, I think you are getting uninitialized floats
here.... maybe specifically set this to (0,0) or (1,1)?

[Khushal, 2017/06/07 00:43:31]

(0,0) it is. Since I want it to use the smallest scale possible. 

+    gfx::ColorSpace color_space;
+  };
+
   // Wrapper to unlock an image decode requested from the ImageController on
   // destruction.
   class ScopedDecodeHolder {
    public:
     ScopedDecodeHolder(ImageController* controller,
                        ImageController::ImageDecodeRequestId request_id)
         : controller_(controller), request_id_(request_id) {}
     ~ScopedDecodeHolder() { controller_->UnlockImageDecode(request_id_); }
 
    private:
     ImageController* controller_;
     ImageController::ImageDecodeRequestId request_id_;
 
     DISALLOW_COPY_AND_ASSIGN(ScopedDecodeHolder);
   };
 
   void DidFinishImageDecode(PaintImage::Id image_id,
                             ImageController::ImageDecodeRequestId request_id,
                             ImageController::ImageDecodeResult result);
 
   // Called when the next request in the |image_decode_queue_| should be
   // scheduled with the image decode service.
   void ScheduleNextImageDecode();
+  void UpdateDecodeState(const DrawImage& draw_image,
+                         PaintImage::Id paint_image_id,
+                         DecodeState* decode_state);
 
   ImageController* image_controller_;
   CheckerImageTrackerClient* client_;
   const bool enable_checker_imaging_;
 
   // A set of images which have been decoded and are pending invalidation for
   // raster on the checkered tiles.
   PaintImageIdFlatSet images_pending_invalidation_;
 
   // A set of images which were invalidated on the current sync tree.
   PaintImageIdFlatSet invalidated_images_on_current_sync_tree_;
 
   // The queue of images pending decode. We maintain a queue to ensure that the
   // order in which images are decoded is aligned with the priority of the tiles
   // dependent on these images.
   ImageDecodeQueue image_decode_queue_;
 
   // The currently outstanding image decode that has been scheduled with the
   // decode service. There can be only one outstanding decode at a time.
   base::Optional<PaintImage> outstanding_image_decode_;
 
   // A map of ImageId to its DecodePolicy.
-  std::unordered_map<PaintImage::Id, DecodePolicy> image_async_decode_state_;
+  std::unordered_map<PaintImage::Id, DecodeState> image_async_decode_state_;
 
   // A map of image id to image decode request id for images to be unlocked.
   std::unordered_map<PaintImage::Id, std::unique_ptr<ScopedDecodeHolder>>
       image_id_to_decode_;
 
   base::WeakPtrFactory<CheckerImageTracker> weak_factory_;
 };
 
 }  // namespace cc
 
 #endif  // CC_TILES_CHECKER_IMAGE_TRACKER_H_