Implementation of device metrics emulation in render view.

content/browser/renderer_host/render_widget_host_view_aura.h

Index: content/browser/renderer_host/render_widget_host_view_aura.h
diff --git a/content/browser/renderer_host/render_widget_host_view_aura.h b/content/browser/renderer_host/render_widget_host_view_aura.h
index f5939df0fc78a6a31313ab362907e88d232dcdc8..001c73bbdfc2e527a0d1dc23b6fadea29338382a 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.h
+++ b/content/browser/renderer_host/render_widget_host_view_aura.h
@@ -223,6 +223,7 @@ class CONTENT_EXPORT RenderWidgetHostViewAura
   virtual gfx::Rect GetBoundsInRootWindow() OVERRIDE;
   virtual void GestureEventAck(int gesture_event_type,
                                InputEventAckState ack_result) OVERRIDE;
+  virtual void SetExpectedRenderedSize(const gfx::Size& size) OVERRIDE;
   virtual void ProcessAckedTouchEvent(
       const TouchEventWithLatencyInfo& touch,
       InputEventAckState ack_result) OVERRIDE;
@@ -658,6 +659,10 @@ class CONTENT_EXPORT RenderWidgetHostViewAura
   // renderer of producing a frame of the right size.
   scoped_ptr<ResizeLock> resize_lock_;
 
+  // When emulating screen metrics, renderer may supply image of different size.
+  // Empty size means the default view size is expected.
+  gfx::Size expected_rendered_size_;
+
   // Keeps track of the current frame size.
   gfx::Size current_frame_size_;