compositor-worker: Introduce WebCompositorMutableState

cc/blink/web_compositor_mutable_state_impl.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 CC_BLINK_WEB_COMPOSITOR_MUTABLE_STATE_IMPL_H_
+#define CC_BLINK_WEB_COMPOSITOR_MUTABLE_STATE_IMPL_H_
+
+#include "cc/blink/cc_blink_export.h"
+
+#include "third_party/WebKit/public/platform/WebCompositorMutableState.h"
+
+namespace cc {
+class LayerImpl;
+class LayerTreeMutation;
+}
+
+namespace cc_blink {
+
+class WebCompositorMutableStateImpl : public blink::WebCompositorMutableState {
+ public:
+  WebCompositorMutableStateImpl(cc::LayerTreeMutation* mutation,
+                                cc::LayerImpl* main_layer,
+                                cc::LayerImpl* scroll_layer);
+  ~WebCompositorMutableStateImpl() override;
+
+  double opacity() const override;
+  void setOpacity(double opacity) override;
+
+  const SkMatrix44& transform() const override;
+  void setTransform(const SkMatrix44& transform) override;
+
+  double scrollLeft() const override;
+  void setScrollLeft(double scroll_left) override;
+
+  double scrollTop() const override;
+  void setScrollTop(double scroll_top) override;
+
+ private:
+  cc::LayerTreeMutation* mutation_;
+  cc::LayerImpl* main_layer_;
+  cc::LayerImpl* scroll_layer_;
+};
+
+}  // namespace cc_blink
+
+#endif  // CC_BLINK_WEB_COMPOSITOR_MUTABLE_STATE_IMPL_H_