cc: Add image decode queue functionality to image manager.

cc/layers/layer_unittest.cc

Index: cc/layers/layer_unittest.cc
diff --git a/cc/layers/layer_unittest.cc b/cc/layers/layer_unittest.cc
index 4dc33758fde2f0aac083db3900b676409204cffd..50790f6f4c1f645895ff2225761cef18cc160584 100644
--- a/cc/layers/layer_unittest.cc
+++ b/cc/layers/layer_unittest.cc
@@ -133,6 +133,7 @@ class LayerTest : public testing::Test {
     params.settings = &settings_;
     params.task_graph_runner = &task_graph_runner_;
     params.mutator_host = animation_host_.get();
+    params.image_worker_task_runner = nullptr;

[enne (OOO), 2017/01/03 21:15:25]

Doesn't this default to nullptr?

[vmpstr, 2017/01/03 21:40:34]

Yes. Uh... Well, this is a relic of the past. As in, I went through a lot of
iterations some of which required this. In the end, I decided to leave it here
as an explicit "I know there's a param here called image_worker_task_runner, and
I'm OK with it being nullptr".

I can remove references to this if you prefer.

[enne (OOO), 2017/01/03 21:49:42]

Yah, I think I'd prefer them gone if they're not needed.  :)

[vmpstr, 2017/01/06 01:19:03]

Done.

 
     layer_tree_host_.reset(
         new StrictMock<MockLayerTreeHost>(&single_thread_client_, &params));
@@ -1044,6 +1045,7 @@ class LayerTreeHostFactory {
     params.settings = &settings;
     params.main_task_runner = base::ThreadTaskRunnerHandle::Get();
     params.mutator_host = mutator_host;
+    params.image_worker_task_runner = nullptr;
 
     return LayerTreeHostInProcess::CreateSingleThreaded(&single_thread_client_,
                                                         &params);