content: Implement dynamic priorities for raster threads.

cc/raster/single_thread_task_graph_runner.h

Index: cc/raster/single_thread_task_graph_runner.h
diff --git a/cc/raster/single_thread_task_graph_runner.h b/cc/raster/single_thread_task_graph_runner.h
index 3e8dec076e02af36a9e7c6eb64bd13438c32f499..157b50c976400b2fa3a459eea9572d714dd3d8e5 100644
--- a/cc/raster/single_thread_task_graph_runner.h
+++ b/cc/raster/single_thread_task_graph_runner.h
@@ -20,7 +20,8 @@ namespace cc {
 // Runs TaskGraphs asynchronously using a single worker thread.
 class CC_EXPORT SingleThreadTaskGraphRunner
     : public TaskGraphRunner,
-      public base::DelegateSimpleThread::Delegate {
+      public base::DelegateSimpleThread::Delegate,
+      public TaskGraphWorkQueueClient {
  public:
   SingleThreadTaskGraphRunner();
   ~SingleThreadTaskGraphRunner() override;
@@ -35,6 +36,11 @@ class CC_EXPORT SingleThreadTaskGraphRunner
   // Overridden from base::DelegateSimpleThread::Delegate:
   void Run() override;
 
+  // Overridden from TaskGraphWorkQueueClient:
+  void AdjustWorkerPriorityForTask(Task* task,
+                                   uint16_t old_category,
+                                   uint16_t new_category) override {}
+
   void Start(const std::string& thread_name,
              const base::SimpleThread::Options& thread_options);
   void Shutdown();