Switch ContentSettingsObserver to be a RenderFrameObserver instead of a RenderViewObserver

content/public/browser/web_contents_observer.h

Index: content/public/browser/web_contents_observer.h
===================================================================
--- content/public/browser/web_contents_observer.h	(revision 240912)
+++ content/public/browser/web_contents_observer.h	(working copy)
@@ -52,12 +52,14 @@
   // deleted.
   virtual void RenderFrameDeleted(RenderFrameHost* render_frame_host) {}
 
-  // Only one of the two methods below will be called when a RVH is created for
-  // a WebContents, depending on whether it's for an interstitial or not.
+  // This is called when a RVH is created for a WebContents, but not if it's an
+  // interstitial.
   virtual void RenderViewCreated(RenderViewHost* render_view_host) {}
-  virtual void RenderViewForInterstitialPageCreated(
-      RenderViewHost* render_view_host) {}
 
+  // Called for every RenderFrameHost that's created for an interstitial.
+  virtual void RenderFrameForInterstitialPageCreated(
+      RenderFrameHost* render_frame_host) {}
+
   // This method is invoked when the RenderView of the current RenderViewHost
   // is ready, e.g. because we recreated it after a crash.
   virtual void RenderViewReady() {}