cc: Add image decode queue functionality to image manager.

cc/trees/layer_tree_host_impl.h

Index: cc/trees/layer_tree_host_impl.h
diff --git a/cc/trees/layer_tree_host_impl.h b/cc/trees/layer_tree_host_impl.h
index 2bbf7825465110fb2f64438ac05817790f2ef71a..d51f30710469b94d41b00b2817fe2d748463b631 100644
--- a/cc/trees/layer_tree_host_impl.h
+++ b/cc/trees/layer_tree_host_impl.h
@@ -36,6 +36,7 @@
 #include "cc/scheduler/commit_earlyout_reason.h"
 #include "cc/scheduler/draw_result.h"
 #include "cc/scheduler/video_frame_controller.h"
+#include "cc/tiles/decoded_image_tracker.h"
 #include "cc/tiles/image_decode_cache.h"
 #include "cc/tiles/tile_manager.h"
 #include "cc/trees/layer_tree_mutator.h"
@@ -144,7 +145,8 @@ class CC_EXPORT LayerTreeHostImpl
       RenderingStatsInstrumentation* rendering_stats_instrumentation,
       TaskGraphRunner* task_graph_runner,
       std::unique_ptr<MutatorHost> mutator_host,
-      int id);
+      int id,
+      scoped_refptr<base::SequencedTaskRunner> image_worker_task_runner);
   ~LayerTreeHostImpl() override;
 
   // InputHandler implementation
@@ -594,7 +596,8 @@ class CC_EXPORT LayerTreeHostImpl
       RenderingStatsInstrumentation* rendering_stats_instrumentation,
       TaskGraphRunner* task_graph_runner,
       std::unique_ptr<MutatorHost> mutator_host,
-      int id);
+      int id,
+      scoped_refptr<base::SequencedTaskRunner> image_worker_task_runner);
 
   // Virtual for testing.
   virtual bool AnimateLayers(base::TimeTicks monotonic_time);
@@ -746,6 +749,7 @@ class CC_EXPORT LayerTreeHostImpl
 
   const bool is_synchronous_single_threaded_;
   TileManager tile_manager_;
+  DecodedImageTracker decoded_image_tracker_;
 
   gfx::Vector2dF accumulated_root_overscroll_;