(not for commit) Simplified multi-threaded Ganesh with lock on Flush only.

cc/resources/gpu_tile_task_worker_pool.h

Index: cc/resources/gpu_tile_task_worker_pool.h
diff --git a/cc/resources/gpu_tile_task_worker_pool.h b/cc/resources/gpu_tile_task_worker_pool.h
index 6ac8548a5777847c0276c24945ff9001777cb0d8..b7c21c771dfdd85d68804e7395f1c0e1a1895419 100644
--- a/cc/resources/gpu_tile_task_worker_pool.h
+++ b/cc/resources/gpu_tile_task_worker_pool.h
@@ -6,6 +6,9 @@
 #define CC_RESOURCES_GPU_TILE_TASK_WORKER_POOL_H_
 
 #include "base/memory/weak_ptr.h"
+#include "cc/output/context_provider.h"
+#include "cc/resources/resource_provider.h"
+#include "cc/resources/scoped_gpu_raster.h"
 #include "cc/resources/tile_task_runner.h"
 #include "cc/resources/tile_task_worker_pool.h"
 
@@ -48,9 +51,10 @@ class CC_EXPORT GpuTileTaskWorkerPool : public TileTaskWorkerPool,
 
   scoped_refptr<base::SequencedTaskRunner> task_runner_;
   TaskGraphRunner* task_graph_runner_;
+  ResourceProvider* resource_provider_;
+
   const NamespaceToken namespace_token_;
   TileTaskRunnerClient* client_;
-  ResourceProvider* resource_provider_;
 
   TaskSetCollection tasks_pending_;