WIP - compositor worker mega patch.

cc/animation/layer_tree_mutations.h

Index: cc/animation/layer_tree_mutations.h
diff --git a/cc/animation/layer_tree_mutations.h b/cc/animation/layer_tree_mutations.h
new file mode 100644
index 0000000000000000000000000000000000000000..6adddb64adf4b0f3bb7974fbff8dd9b51a84bba8
--- /dev/null
+++ b/cc/animation/layer_tree_mutations.h
@@ -0,0 +1,16 @@
+// 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_MUTATIONS_H_
+#define CC_ANIMATION_LAYER_TREE_MUTATIONS_H_
+
+namespace cc {
+
+struct LayerTreeMutations {
+  virtual ~LayerTreeMutations() {}
+};
+
+}  // namespace cc
+
+#endif  // CC_ANIMATION_LAYER_TREE_MUTATIONS_H_