compositor-worker: Add CompositorProxyClient worker client of CompositorWorker.

third_party/WebKit/Source/web/CompositorProxyClientImpl.h

+// 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 CompositorProxyClientImpl_h
+#define CompositorProxyClientImpl_h
+
+#include "core/dom/CompositorProxyClient.h"
+#include "wtf/Noncopyable.h"
+
+namespace blink {
+
+class CompositorWorkerGlobalScope;
+class WorkerGlobalScope;
+
+// Mediates between one CompositorWorkerGlobalScope and the associated CompositorMutatorImpl.
+// There is one CompositorProxyClientImpl per worker but there may be multiple for a given
+// mutator, e.g. if a single document creates multiple CompositorWorker objects.
+//
+// Should be accessed only on the compositor thread.
+class CompositorProxyClientImpl final : public GarbageCollected<CompositorProxyClientImpl>, public CompositorProxyClient {
+    USING_GARBAGE_COLLECTED_MIXIN(CompositorProxyClientImpl);
+    WTF_MAKE_NONCOPYABLE(CompositorProxyClientImpl);
+public:
+    CompositorProxyClientImpl();
+    DECLARE_VIRTUAL_TRACE();
+
+    // Runs the animation frame callback for the frame starting at the given time.
+    // Returns true if another animation frame was requested (i.e. should be reinvoked next frame).
+    bool mutate(double monotonicTimeNow);
+
+    // CompositorProxyClient:
+    void setGlobalScope(WorkerGlobalScope*) override;
+    void runAnimationFrameCallbacks() override;
+
+private:
+    bool executeAnimationFrameCallbacks(double monotonicTimeNow);
+
+    Member<CompositorWorkerGlobalScope> m_globalScope;
+    bool m_requestedAnimationFrameCallbacks;
+};
+
+} // namespace blink
+
+#endif // CompositorProxyClientImpl_h