Revert half of the changes from 137638 that are probably causing breakages in

chrome/browser/extensions/extension_tab_helper.h

Index: chrome/browser/extensions/extension_tab_helper.h
diff --git a/chrome/browser/extensions/extension_tab_helper.h b/chrome/browser/extensions/extension_tab_helper.h
index d4a440293c27adabdd9a9e9af8639d2248c80a10..7046863e9f77c30bef301b4cf5e7adc9c2fcf296 100644
--- a/chrome/browser/extensions/extension_tab_helper.h
+++ b/chrome/browser/extensions/extension_tab_helper.h
@@ -40,15 +40,6 @@ class ExtensionTabHelper
       public AppNotifyChannelSetup::Delegate,
       public base::SupportsWeakPtr<ExtensionTabHelper> {
  public:
-  class Observer {
-   public:
-    // Called when the page action state (such as visibility, title) changes.
-    virtual void OnPageActionStateChanged() = 0;
-
-   protected:
-    virtual ~Observer() {}
-  };
-
   explicit ExtensionTabHelper(TabContentsWrapper* wrapper);
   virtual ~ExtensionTabHelper();
 
@@ -66,10 +57,6 @@ class ExtensionTabHelper
   // the data is available.
   void GetApplicationInfo(int32 page_id);
 
-  // Observer management.
-  void AddObserver(Observer* observer);
-  void RemoveObserver(Observer* observer);
-
   // App extensions ------------------------------------------------------------
 
   // Sets the extension denoting this as an app. If |extension| is non-null this