Switch ContentSettingsObserver to be a RenderFrameObserver instead of a RenderViewObserver

chrome/renderer/plugins/chrome_plugin_placeholder.h

Index: chrome/renderer/plugins/chrome_plugin_placeholder.h
===================================================================
--- chrome/renderer/plugins/chrome_plugin_placeholder.h	(revision 240362)
+++ chrome/renderer/plugins/chrome_plugin_placeholder.h	(working copy)
@@ -97,11 +97,6 @@
   int context_menu_request_id_;  // Nonzero when request pending.
   base::string16 plugin_name_;
 
-  // TODO(jam): remove this class, it's temporary until ContentSettingObserver
-  // is a RenderFrameObserver.
-  class RenderViewObserver;
-  scoped_ptr<RenderViewObserver> view_observer_;
-
   DISALLOW_COPY_AND_ASSIGN(ChromePluginPlaceholder);
 };