SkyView should handle screen rotation

sky/engine/core/view/View.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 SKY_ENGINE_CORE_VIEW_VIEW_H_
 #define SKY_ENGINE_CORE_VIEW_VIEW_H_
 
 #include "base/callback.h"
 #include "base/time/time.h"
+#include "sky/engine/core/html/VoidCallback.h"
 #include "sky/engine/core/painting/Picture.h"
 #include "sky/engine/core/view/BeginFrameCallback.h"
 #include "sky/engine/core/view/EventCallback.h"
 #include "sky/engine/public/platform/sky_display_metrics.h"
 #include "sky/engine/tonic/dart_wrappable.h"
 #include "sky/engine/wtf/PassRefPtr.h"
 #include "sky/engine/wtf/RefCounted.h"
 
 namespace blink {
 
 class View : public RefCounted<View>, public DartWrappable {
     DEFINE_WRAPPERTYPEINFO();
 public:
     ~View() override;
     static PassRefPtr<View> create(const base::Closure& scheduleFrameCallback);
 
     double devicePixelRatio() const { return m_displayMetrics.device_pixel_ratio; }
     double width() const;
     double height() const;
 
     Picture* picture() const { return m_picture.get(); }
     void setPicture(Picture* picture) { m_picture = picture; }
 
     void setEventCallback(PassOwnPtr<EventCallback> callback);
 
+    void setMetricsChangedCallback(PassOwnPtr<VoidCallback> callback);
+
     void setBeginFrameCallback(PassOwnPtr<BeginFrameCallback> callback);
     void scheduleFrame();
 
     void setDisplayMetrics(const SkyDisplayMetrics& metrics);
     void handleInputEvent(PassRefPtr<Event> event);
     void beginFrame(base::TimeTicks frameTime);
 
 private:
     explicit View(const base::Closure& scheduleFrameCallback);
 
     base::Closure m_scheduleFrameCallback;
     SkyDisplayMetrics m_displayMetrics;
     OwnPtr<EventCallback> m_eventCallback;
+    OwnPtr<VoidCallback> m_metricsChangedCallback;
     OwnPtr<BeginFrameCallback> m_beginFrameCallback;
     RefPtr<Picture> m_picture;
 };
 
 } // namespace blink
 
 #endif  // SKY_ENGINE_CORE_VIEW_VIEW_H_