compositor-worker: Initialize CW machinery plumbing to compositor and fire CW rAF callbacks.

third_party/WebKit/Source/platform/graphics/CompositorMutatorClient.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 CompositorMutatorClient_h
 #define CompositorMutatorClient_h
 
 #include "platform/PlatformExport.h"
+#include "platform/heap/Handle.h"
 #include "public/platform/WebCompositorMutatorClient.h"
 #include "wtf/OwnPtr.h"
 #include "wtf/PassOwnPtr.h"
 
 namespace blink {
 
+class CompositorMutator;
 struct CompositorMutations;
 class CompositorMutationsTarget;
 
 class PLATFORM_EXPORT CompositorMutatorClient : public WebCompositorMutatorClient {
 public:
-    CompositorMutatorClient(CompositorMutationsTarget*);
+    CompositorMutatorClient(CompositorMutator*, CompositorMutationsTarget*);

[jbroman, 2016/04/29 19:42:22]

Is it or is it not okay for the CompositorMutator* to be null? It's used without
null checks, but the unit tests provide nullptr.

[flackr, 2016/05/03 22:24:54]

The current CompositorMutatorClient tests just verify that the client correctly
returns passes along the tracked mutations but it doesn't actually call anything
requiring a CompositorMutator.

[jbroman, 2016/05/04 17:59:00]

Hmm. Alright, though it seems a little suspicious to me that the unit tests rely
on this. It might be cleaner to have the unit tests supply a do-nothing
CompositorMutator, so that this class doesn't have to preserve that behaviour to
keep the unit tests.

But I don't feel strongly about this, so if you'd rather not, that's okay.

[flackr, 2016/05/04 21:52:40]

It's done. May as well have the stub in place and consistently always pass a
mutator.

     virtual ~CompositorMutatorClient();
 
+    void setNeedsMutate();
+
     // cc::LayerTreeMutator
+    bool Mutate(base::TimeTicks monotonicTime) override;
+    void SetClient(cc::LayerTreeMutatorClient*) override;
     base::Closure TakeMutations() override;
 
+    CompositorMutator* mutator() { return m_mutator.get(); }
+
     void setMutationsForTesting(PassOwnPtr<CompositorMutations>);
 private:
+    cc::LayerTreeMutatorClient* m_client;
     CompositorMutationsTarget* m_mutationsTarget;
+    Persistent<CompositorMutator> m_mutator;
     OwnPtr<CompositorMutations> m_mutations;
 };
 
 } // namespace blink
 
 #endif // CompositorMutatorClient_h