cc: Add image decode queue functionality to image manager.

cc/trees/layer_tree_host_in_process.h

Index: cc/trees/layer_tree_host_in_process.h
diff --git a/cc/trees/layer_tree_host_in_process.h b/cc/trees/layer_tree_host_in_process.h
index eec439482d637aa23a31ec76b41837919c9b9249..909dce784e125d695f4fa734771af4f068d66e1f 100644
--- a/cc/trees/layer_tree_host_in_process.h
+++ b/cc/trees/layer_tree_host_in_process.h
@@ -74,7 +74,8 @@ class CC_EXPORT LayerTreeHostInProcess : public LayerTreeHost {
     LayerTreeSettings const* settings = nullptr;
     scoped_refptr<base::SingleThreadTaskRunner> main_task_runner;
     ImageSerializationProcessor* image_serialization_processor = nullptr;
-    MutatorHost* mutator_host;
+    MutatorHost* mutator_host = nullptr;
+    scoped_refptr<base::SequencedTaskRunner> image_worker_task_runner;
 
     InitParams();
     ~InitParams();
@@ -317,6 +318,8 @@ class CC_EXPORT LayerTreeHostInProcess : public LayerTreeHost {
   // should get these PropertyTrees directly from blink?
   std::unique_ptr<ReflectedMainFrameState> reflected_main_frame_state_;
 
+  scoped_refptr<base::SequencedTaskRunner> image_worker_task_runner_;
+
   DISALLOW_COPY_AND_ASSIGN(LayerTreeHostInProcess);
 };