cc: Optimize decode scheduling for checker-images.

cc/tiles/tile_manager.h

Index: cc/tiles/tile_manager.h
diff --git a/cc/tiles/tile_manager.h b/cc/tiles/tile_manager.h
index 5de0a15485a61a511906fa1552354f07d906643d..31007fc6b02db97d485cba57a84e357da8ac7297 100644
--- a/cc/tiles/tile_manager.h
+++ b/cc/tiles/tile_manager.h
@@ -282,7 +282,8 @@ class CC_EXPORT TileManager : CheckerImageTrackerClient {
   void FreeResourcesForTileAndNotifyClientIfTileWasReadyToDraw(Tile* tile);
   scoped_refptr<TileTask> CreateRasterTask(
       const PrioritizedTile& prioritized_tile,
-      const gfx::ColorSpace& color_space);
+      const gfx::ColorSpace& color_space,
+      CheckerImageTracker::ImageDecodeQueue* checker_image_decode_queue);
 
   std::unique_ptr<EvictionTilePriorityQueue>
   FreeTileResourcesUntilUsageIsWithinLimit(
@@ -314,6 +315,13 @@ class CC_EXPORT TileManager : CheckerImageTrackerClient {
   PrioritizedWorkToSchedule AssignGpuMemoryToTiles();
   void ScheduleTasks(const PrioritizedWorkToSchedule& work_to_schedule);
 
+  void FilterImagesForCheckering(

[vmpstr, 2017/03/29 19:11:46]

This needs a comment explaining what each parameter is, since 

images_to_decode_for_raster, checkered_images, and image_decode_queue all seem
to store the same thing. Possibly, this needs to be reworked to move some code
outside of the function. 

In my mind, the output of this should be fewer vectors/sets/queues and the
calling code will then use the vector to populate/append to the queue or
something like that.

That being said, I haven't looked at the implementation yet and just commenting
on the header.

[Khushal, 2017/03/31 04:31:01]

The function was killed.

+      WhichTree tree,
+      const std::vector<DrawImage>& images_in_tile,
+      std::vector<DrawImage>* images_to_decode_for_raster,

[vmpstr, 2017/03/29 19:11:46]

just images_to_decode is enough I think.

+      ImageIdFlatSet* checkered_images,
+      CheckerImageTracker::ImageDecodeQueue* image_decode_queue);
+
   std::unique_ptr<base::trace_event::ConvertableToTraceFormat>
   ScheduledTasksStateAsValue() const;