Allow task pools to reason about transparency.

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 7dcdff0a68653c9e80b4797b3d7b04e664022ff3..b1015593245d12af3d39a272680dee4c32774224 100644
--- a/cc/raster/zero_copy_tile_task_worker_pool.h
+++ b/cc/raster/zero_copy_tile_task_worker_pool.h
@@ -28,7 +28,8 @@ class CC_EXPORT ZeroCopyTileTaskWorkerPool : public TileTaskWorkerPool,
   static scoped_ptr<TileTaskWorkerPool> Create(
       base::SequencedTaskRunner* task_runner,
       TaskGraphRunner* task_graph_runner,
-      ResourceProvider* resource_provider);
+      ResourceProvider* resource_provider,
+      bool use_rgba_4444_texture_format);
 
   // Overridden from TileTaskWorkerPool:
   TileTaskRunner* AsTileTaskRunner() override;
@@ -38,8 +39,8 @@ class CC_EXPORT ZeroCopyTileTaskWorkerPool : public TileTaskWorkerPool,
   void Shutdown() override;
   void ScheduleTasks(TileTaskQueue* queue) override;
   void CheckForCompletedTasks() override;
-  ResourceFormat GetResourceFormat() const override;
-  bool GetResourceRequiresSwizzle() const override;
+  ResourceFormat GetResourceFormat(bool must_support_alpha) const override;
+  bool GetResourceRequiresSwizzle(bool must_support_alpha) const override;
 
   // Overridden from TileTaskClient:
   scoped_ptr<RasterBuffer> AcquireBufferForRaster(
@@ -51,7 +52,8 @@ class CC_EXPORT ZeroCopyTileTaskWorkerPool : public TileTaskWorkerPool,
  protected:
   ZeroCopyTileTaskWorkerPool(base::SequencedTaskRunner* task_runner,
                              TaskGraphRunner* task_graph_runner,
-                             ResourceProvider* resource_provider);
+                             ResourceProvider* resource_provider,
+                             bool use_rgba_4444_texture_format);
 
  private:
   void OnTaskSetFinished(TaskSet task_set);
@@ -64,6 +66,8 @@ class CC_EXPORT ZeroCopyTileTaskWorkerPool : public TileTaskWorkerPool,
   TileTaskRunnerClient* client_;
   ResourceProvider* resource_provider_;
 
+  bool use_rgba_4444_texture_format_;
+
   TaskSetCollection tasks_pending_;
 
   scoped_refptr<TileTask> task_set_finished_tasks_[kNumberOfTaskSets];