cc: Simplify task and its derived classes.

cc/raster/gpu_tile_task_worker_pool.h

Index: cc/raster/gpu_tile_task_worker_pool.h
diff --git a/cc/raster/gpu_tile_task_worker_pool.h b/cc/raster/gpu_tile_task_worker_pool.h
index 0577b51fdfb70e1ac620bbe491a049f2a4d4ba59..f9c1047f95c4a54d4218103c134490b2bcc124f7 100644
--- a/cc/raster/gpu_tile_task_worker_pool.h
+++ b/cc/raster/gpu_tile_task_worker_pool.h
@@ -17,8 +17,7 @@ class GpuRasterizer;
 class ResourceProvider;
 
 class CC_EXPORT GpuTileTaskWorkerPool : public TileTaskWorkerPool,
-                                        public TileTaskRunner,
-                                        public TileTaskClient {
+                                        public TileTaskRunner {
  public:
   ~GpuTileTaskWorkerPool() override;
 
@@ -33,6 +32,13 @@ class CC_EXPORT GpuTileTaskWorkerPool : public TileTaskWorkerPool,
   // Overridden from TileTaskWorkerPool:
   TileTaskRunner* AsTileTaskRunner() override;
 
+  // Overridden from RasterBufferProvider:
+  scoped_ptr<RasterBuffer> AcquireBufferForRaster(
+      const Resource* resource,
+      uint64_t resource_content_id,
+      uint64_t previous_content_id) override;
+  void ReleaseBufferForRaster(scoped_ptr<RasterBuffer> buffer) override;
+
   // Overridden from TileTaskRunner:
   void Shutdown() override;
   void ScheduleTasks(TaskGraph* graph) override;
@@ -40,13 +46,6 @@ class CC_EXPORT GpuTileTaskWorkerPool : public TileTaskWorkerPool,
   ResourceFormat GetResourceFormat(bool must_support_alpha) const override;
   bool GetResourceRequiresSwizzle(bool must_support_alpha) const override;
 
-  // Overridden from TileTaskClient:
-  scoped_ptr<RasterBuffer> AcquireBufferForRaster(
-      const Resource* resource,
-      uint64_t resource_content_id,
-      uint64_t previous_content_id) override;
-  void ReleaseBufferForRaster(scoped_ptr<RasterBuffer> buffer) override;
-
  private:
   GpuTileTaskWorkerPool(base::SequencedTaskRunner* task_runner,
                         TaskGraphRunner* task_graph_runner,