Implementation of device metrics emulation in render view.

content/port/browser/render_widget_host_view_port.h

Index: content/port/browser/render_widget_host_view_port.h
diff --git a/content/port/browser/render_widget_host_view_port.h b/content/port/browser/render_widget_host_view_port.h
index d13a125049bdbd0980392918f2425d034b570d4c..42032c948b888ceb51cd6d2474437af185d2538e 100644
--- a/content/port/browser/render_widget_host_view_port.h
+++ b/content/port/browser/render_widget_host_view_port.h
@@ -253,6 +253,11 @@ class CONTENT_EXPORT RenderWidgetHostViewPort : public RenderWidgetHostView,
   // Gets the bounds of the window, in screen coordinates.
   virtual gfx::Rect GetBoundsInRootWindow() = 0;
 
+  // Set expected image size coming from renderer. This is essential to emulate
+  // screen metrics, where render widget renders only a part of the view.
+  // Empty |size| means that default view size is expected.
+  virtual void SetExpectedRenderedSize(const gfx::Size& size) = 0;
+
   virtual gfx::GLSurfaceHandle GetCompositingSurface() = 0;
 
   // Because the associated remote WebKit instance can asynchronously