Cross-process frames should be notified of device scale factor changes.

content/browser/renderer_host/render_widget_host_delegate.h

Index: content/browser/renderer_host/render_widget_host_delegate.h
diff --git a/content/browser/renderer_host/render_widget_host_delegate.h b/content/browser/renderer_host/render_widget_host_delegate.h
index 6777b9c999261e7fc63cbc10a9d51c45dbc9a3ff..7e96ccf013348c7510627719fc47e64170cbf37e 100644
--- a/content/browser/renderer_host/render_widget_host_delegate.h
+++ b/content/browser/renderer_host/render_widget_host_delegate.h
@@ -61,6 +61,12 @@ class CONTENT_EXPORT RenderWidgetHostDelegate {
   // The screen info has changed.
   virtual void ScreenInfoChanged() {}
 
+  // Sets the device scale factor for frames associated with this WebContents.
+  virtual void UpdateDeviceScaleFactor(double device_scale_factor) {}
+
+  // Value to be used in view creation when no window has been specified.
+  virtual double DefaultDeviceScaleFactor();
+
   // Callback to give the browser a chance to handle the specified keyboard
   // event before sending it to the renderer.
   // Returns true if the |event| was handled. Otherwise, if the |event| would