Make PageScaleFactor work for oopif subframes.

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 79efc0ff2a52aec1b35575b3c57998cb047abac1..2efdcbc7e71ea509f49eab15ad40a5cbb6647882 100644
--- a/content/browser/renderer_host/render_widget_host_delegate.h
+++ b/content/browser/renderer_host/render_widget_host_delegate.h
@@ -74,6 +74,10 @@ class CONTENT_EXPORT RenderWidgetHostDelegate {
   // Sets the device scale factor for frames associated with this WebContents.
   virtual void UpdateDeviceScaleFactor(double device_scale_factor) {}
 
+  // Sets the device scale factor for cross-process subframes associated with
+  // this WebContents.
+  virtual void SetPageScaleFactorForSubframes(double page_scale_factor) {}
+
   // Retrieve screen information.
   virtual void GetScreenInfo(ScreenInfo* web_screen_info);