cc: Simplify task and its derived classes.

cc/raster/zero_copy_tile_task_worker_pool.h

Index: cc/raster/zero_copy_tile_task_worker_pool.h
diff --git a/cc/raster/zero_copy_tile_task_worker_pool.h b/cc/raster/zero_copy_tile_task_worker_pool.h
index bc558d762ce9e103022ad7a11ba08dccecce1e06..eea085f4c493967c1805618f0d24704e0cd163c7 100644
--- a/cc/raster/zero_copy_tile_task_worker_pool.h
+++ b/cc/raster/zero_copy_tile_task_worker_pool.h
@@ -23,8 +23,7 @@ namespace cc {
 class ResourceProvider;
 
 class CC_EXPORT ZeroCopyTileTaskWorkerPool : public TileTaskWorkerPool,
-                                             public TileTaskRunner,
-                                             public TileTaskClient {
+                                             public TileTaskRunner {
  public:
   ~ZeroCopyTileTaskWorkerPool() override;
 
@@ -37,6 +36,13 @@ class CC_EXPORT ZeroCopyTileTaskWorkerPool : 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;
@@ -44,13 +50,6 @@ class CC_EXPORT ZeroCopyTileTaskWorkerPool : 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:
   ZeroCopyTileTaskWorkerPool(base::SequencedTaskRunner* task_runner,
                              TaskGraphRunner* task_graph_runner,