Update from https://crrev.com/309415

cc/resources/tile_task_worker_pool.h

Index: cc/resources/tile_task_worker_pool.h
diff --git a/cc/resources/tile_task_worker_pool.h b/cc/resources/tile_task_worker_pool.h
index 044065539ad65a68c6209f03efa7c6e0e47b488f..cb7d4b08776c384c746ac902db0037489f8c704a 100644
--- a/cc/resources/tile_task_worker_pool.h
+++ b/cc/resources/tile_task_worker_pool.h
@@ -5,6 +5,7 @@
 #ifndef CC_RESOURCES_TILE_TASK_WORKER_POOL_H_
 #define CC_RESOURCES_TILE_TASK_WORKER_POOL_H_
 
+#include "base/threading/platform_thread.h"
 #include "cc/resources/tile_task_runner.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/geometry/size.h"
@@ -34,6 +35,9 @@ class CC_EXPORT TileTaskWorkerPool {
   // Returns the number of threads used for the global TaskGraphRunner instance.
   static int GetNumWorkerThreads();
 
+  // Set the priority of worker threads.
+  static void SetWorkerThreadPriority(base::ThreadPriority priority);
+
   // Returns a pointer to the global TaskGraphRunner instance.
   static TaskGraphRunner* GetTaskGraphRunner();