compositor-worker: cc->blink mutation plumbing

cc/animation/layer_tree_mutator.h

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CC_ANIMATION_LAYER_TREE_MUTATOR_H_
+#define CC_ANIMATION_LAYER_TREE_MUTATOR_H_
+
+#include "base/callback_forward.h"
+#include "cc/base/cc_export.h"
+
+namespace cc {
+
+class CC_EXPORT LayerTreeMutator {
+ public:
+  virtual ~LayerTreeMutator() {}
+
+  // Returns a callback which is responsible for applying layer tree mutations
+  // to DOM elements.
+  virtual base::Closure TakeMutations() = 0;
+};
+
+}  // namespace cc
+
+#endif  // CC_ANIMATION_LAYER_TREE_MUTATOR_H_