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..63d677099449eb7eec8f288e14a72c89bb5a5086 100644
--- a/cc/raster/bitmap_tile_task_worker_pool.h
+++ b/cc/raster/bitmap_tile_task_worker_pool.h
@@ -23,7 +23,7 @@ class ResourceProvider;
 
 class CC_EXPORT BitmapTileTaskWorkerPool : public TileTaskWorkerPool,
                                            public TileTaskRunner,
-                                           public TileTaskClient {
+                                           public DependencyTaskClient {
  public:
   ~BitmapTileTaskWorkerPool() override;
 
@@ -42,7 +42,7 @@ 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:
+  // Overridden from DependencyTaskClient:
   scoped_ptr<RasterBuffer> AcquireBufferForRaster(
       const Resource* resource,
       uint64_t resource_content_id,
@@ -62,7 +62,7 @@ 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);
 };