compositor-worker: Introduce WebCompositorMutableState

third_party/WebKit/public/platform/WebCompositorMutableStateProvider.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 WebCompositorMutableStateProvider_h
+#define WebCompositorMutableStateProvider_h
+
+#include "public/platform/WebPassOwnPtr.h"
+
+#include <cstdint>
+
+namespace blink {
+
+class WebCompositorMutableState;
+
+// This class is a window onto compositor-owned state. It vends out wrappers
+// around per-element bits of this state.
+class WebCompositorMutableStateProvider {
+public:
+    virtual ~WebCompositorMutableStateProvider() { }
+
+    // The caller is expected to take ownership.
+    virtual WebPassOwnPtr<WebCompositorMutableState> getMutableStateFor(uint64_t elementId) = 0;
+};
+
+} // namespace blink
+
+#endif // WebCompositorMutableStateProvider_h