cc: Simplify task and its derived classes.

cc/raster/bitmap_tile_task_worker_pool.h

Index: cc/raster/bitmap_tile_task_worker_pool.h
diff --git a/cc/raster/bitmap_tile_task_worker_pool.h b/cc/raster/bitmap_tile_task_worker_pool.h
index 7fea2b2dcfd21a5dbfe0edd6040e1bdb3f5858c8..6d92f62f75ce3385fac2ddbcf95c80d9f7e7b0fd 100644
--- a/cc/raster/bitmap_tile_task_worker_pool.h
+++ b/cc/raster/bitmap_tile_task_worker_pool.h
@@ -22,8 +22,7 @@ namespace cc {
 class ResourceProvider;
 
 class CC_EXPORT BitmapTileTaskWorkerPool : public TileTaskWorkerPool,
-                                           public TileTaskRunner,
-                                           public TileTaskClient {
+                                           public TileTaskRunner {
  public:
   ~BitmapTileTaskWorkerPool() override;
 
@@ -35,6 +34,13 @@ class CC_EXPORT BitmapTileTaskWorkerPool : 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;
@@ -42,13 +48,6 @@ class CC_EXPORT BitmapTileTaskWorkerPool : 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;
-
  protected:
   BitmapTileTaskWorkerPool(base::SequencedTaskRunner* task_runner,
                            TaskGraphRunner* task_graph_runner,
@@ -62,7 +61,7 @@ class CC_EXPORT BitmapTileTaskWorkerPool : public TileTaskWorkerPool,
   const NamespaceToken namespace_token_;
   ResourceProvider* resource_provider_;
 
-  Task::Vector completed_tasks_;
+  DependencyTask::Vector completed_tasks_;
 
   DISALLOW_COPY_AND_ASSIGN(BitmapTileTaskWorkerPool);
 };