cc: Add checker-imaging support to TileManager.

cc/tiles/checker_image_tracker.h

Index: cc/tiles/checker_image_tracker.h
diff --git a/cc/tiles/checker_image_tracker.h b/cc/tiles/checker_image_tracker.h
new file mode 100644
index 0000000000000000000000000000000000000000..196190730f761fb6cbb0f11d74b89baabee7d7ad
--- /dev/null
+++ b/cc/tiles/checker_image_tracker.h
@@ -0,0 +1,91 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.

[vmpstr, 2017/02/03 23:42:32]

2017

[Khushal, 2017/02/07 00:25:32]

Done.

+// 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 <unordered_set>
+#include <vector>
+
+#include "cc/playback/image_id.h"
+#include "cc/tiles/image_controller.h"
+#include "third_party/skia/include/core/SkImage.h"
+
+namespace cc {
+class LayerTreeImpl;
+class PrioritizedTile;
+
+class CheckerImageTrackerClient {
+ public:
+  virtual ~CheckerImageTrackerClient() {}
+
+  virtual void NeedsInvalidationForCheckerImagedTiles() = 0;
+};
+
+class CheckerImageTracker {
+ public:
+  CheckerImageTracker(ImageController* image_controller,
+                      CheckerImageTrackerClient* client,
+                      bool enable_checker_imaging);
+  ~CheckerImageTracker();
+
+  // For the given |prioritized_tile|, populates |images| with the set of images
+  // that must be decoded before this tile can be rastered.
+  // |checkered_images| will be populated with set of images which will be
+  // decoded using the Image Decode Service and must be skipped during
+  // rasterization of this tile.
+  void FilterImagesForCheckeringForTile(
+      const PrioritizedTile& prioritized_tile,
+      std::vector<DrawImage>* images,
+      std::unordered_set<ImageId>* checkered_images);
+
+  // Invalidates the region for decoded images on the sync tree.
+  void AddInvalidationForCheckerImages(LayerTreeImpl* sync_tree);
+
+  void DidActivateSyncTree();
+
+ private:
+  void DidFinishImageDecode(ImageId image_id,
+                            ImageController::ImageDecodeRequestId request_id);
+
+  // Returns true if the decode for |image| will be deferred to the image decode
+  // service and it should be be skipped during raster.
+  bool AnalyzeImageForCheckeringAndScheduleDecodeIfNecessary(
+      const sk_sp<const SkImage> image,
+      WhichTree tree);
+
+  ImageController* image_controller_;
+  CheckerImageTrackerClient* client_;
+  const bool enable_checker_imaging_;
+
+  using ImageIdSet = std::unordered_set<ImageId>;

[vmpstr, 2017/02/03 23:42:32]

I wonder if we should just use a vector. It might be worth writing a perf test
to see. I don't know if we expect there to be a lot of duplicate entries.

[Khushal, 2017/02/07 00:25:32]

The set was more for the look up cost. The |images_decoded_once_| set for
instance will keep growing and we'll query it for every tile.

+
+  // A set of images which have been decoded and are pending invalidation for
+  // raster on the checkered tiles.
+  ImageIdSet images_pending_invalidation_;
+
+  // A set of images which were invalidated on the current sync tree.
+  ImageIdSet images_invalidated_on_current_sync_tree_;

[vmpstr, 2017/02/03 23:42:32]

nit: invalidated_images_

[Khushal, 2017/02/07 00:25:32]

Done.

+
+  // A set of images which are currently pending decode from the image decode
+  // service.
+  // TODO(khushalsagar): This should be a queue that gets re-built each time we

[vmpstr, 2017/02/03 23:42:32]

We can file a bug as a follow up for this.

[Khushal, 2017/02/07 00:25:32]

Done.

+  // do a PrepareTiles?
+  ImageIdSet pending_image_decodes_;
+
+  // A set of images which have been decoded at least once from the
+  // ImageDecodeService and should not be checkered again.
+  ImageIdSet images_decoded_once_;
+
+  // A map of image id to image decode request id for images to be unlocked.
+  std::unordered_map<ImageId, ImageController::ImageDecodeRequestId>
+      image_id_to_decode_request_id_;
+
+  base::WeakPtrFactory<CheckerImageTracker> weak_factory_;
+};
+
+}  // namespace cc
+
+#endif  // CC_TILES_CHECKER_IMAGE_TRACKER_H_