cc: Simplify task and its derived classes.

cc/raster/one_copy_tile_task_worker_pool.h

Index: cc/raster/one_copy_tile_task_worker_pool.h
diff --git a/cc/raster/one_copy_tile_task_worker_pool.h b/cc/raster/one_copy_tile_task_worker_pool.h
index fce75fe2af8138506be4166c088de37d4615487c..2416e045e3e001d108d11c0b6f9a9f142e748193 100644
--- a/cc/raster/one_copy_tile_task_worker_pool.h
+++ b/cc/raster/one_copy_tile_task_worker_pool.h
@@ -40,7 +40,7 @@ class ResourcePool;
 class CC_EXPORT OneCopyTileTaskWorkerPool
     : public TileTaskWorkerPool,
       public TileTaskRunner,
-      public TileTaskClient,
+      public DependencyTaskClient,
       public base::trace_event::MemoryDumpProvider {
  public:
   ~OneCopyTileTaskWorkerPool() override;
@@ -65,7 +65,7 @@ class CC_EXPORT OneCopyTileTaskWorkerPool
   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,
@@ -140,7 +140,7 @@ class CC_EXPORT OneCopyTileTaskWorkerPool
   const int max_bytes_per_copy_operation_;
   const bool use_partial_raster_;
 
-  Task::Vector completed_tasks_;
+  DependencyTask::Vector completed_tasks_;
 
   mutable base::Lock lock_;
   // |lock_| must be acquired when accessing the following members.