[compositorworker] compositor proxy mutation updates underlying layers

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(CompositorMutator*, CompositorMutationsTarget*);
     virtual ~CompositorMutatorClient();
 
     void setNeedsMutate();
 
     // cc::LayerTreeMutator
-    bool Mutate(base::TimeTicks monotonicTime) override;
+    bool Mutate(base::TimeTicks monotonicTime, cc::LayerTreeImpl* state) override;

[jbroman, 2016/06/08 14:59:38]

"state" seems an odd name for a LayerTreeImpl* (here and at the interface method
definition); what does this mean?

[majidvp, 2016/06/08 21:50:09]

This is following the convention used in CompositorMutableStateProvider.

I think the intention has been that in this context layer tree impl is the 
underlying state we are mutating. But I agree that it is perhaps better to just
use |tree_impl| and reserve state for referring to its wrapper which 
is CompositorMutableState.
wdyt?

     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