WIP - compositor worker mega patch.

cc/animation/layer_tree_mutator.h

Index: cc/animation/layer_tree_mutator.h
diff --git a/cc/animation/layer_tree_mutator.h b/cc/animation/layer_tree_mutator.h
new file mode 100644
index 0000000000000000000000000000000000000000..45fbb39b52e16ded3e5fce89883660f2b0e338c2
--- /dev/null
+++ b/cc/animation/layer_tree_mutator.h
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+// Copyright 2015 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/memory/scoped_ptr.h"
+#include "base/time/time.h"
+
+#include "cc/animation/layer_tree_mutations.h"
+
+namespace cc {
+
+class LayerTreeImpl;
+
+class LayerTreeMutatorClient {
+ public:
+  // This is necessary because it forces an impl frame. We couldn't, for
+  // example, just assume that we will "always mutate" and early-out in the
+  // mutator if there was nothing to do because we won't always be producing
+  // impl frames.
+  virtual void SetNeedsMutate() = 0;
+};
+
+class LayerTreeMutator {
+ public:
+  virtual ~LayerTreeMutator() {}
+
+  // Returns true if the mutator should be rescheduled.
+  virtual bool Mutate(base::TimeTicks now, LayerTreeImpl* state) = 0;
+  virtual void SetClient(LayerTreeMutatorClient* client) = 0;
+  virtual scoped_ptr<LayerTreeMutations> TakeMutations() = 0;
+};
+
+}  // namespace cc
+
+#endif  // CC_ANIMATION_LAYER_TREE_MUTATOR_H_