Only return the visible page actions from PageActionController.

chrome/browser/extensions/extension_tab_helper.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_EXTENSION_TAB_HELPER_H_
 #define CHROME_BROWSER_EXTENSIONS_EXTENSION_TAB_HELPER_H_
 #pragma once
 
 #include "base/memory/weak_ptr.h"
+#include "base/observer_list.h"
 #include "chrome/browser/extensions/app_notify_channel_setup.h"
 #include "chrome/browser/extensions/extension_function_dispatcher.h"
 #include "chrome/browser/extensions/image_loading_tracker.h"
 #include "chrome/browser/extensions/webstore_inline_installer.h"
 #include "chrome/common/web_apps.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 
 class Extension;
 class ExtensionTabHelperDelegate;
 class TabContentsWrapper;
 struct WebApplicationInfo;
 
 namespace content {
 struct LoadCommittedDetails;
 }
 
 // Per-tab extension helper. Also handles non-extension apps.
 class ExtensionTabHelper
     : public content::WebContentsObserver,
       public ExtensionFunctionDispatcher::Delegate,
       public ImageLoadingTracker::Observer,
       public WebstoreInlineInstaller::Delegate,
       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();
 
   // Copies the internal state from another ExtensionTabHelper.
   void CopyStateFrom(const ExtensionTabHelper& source);
 
   ExtensionTabHelperDelegate* delegate() const { return delegate_; }
   void set_delegate(ExtensionTabHelperDelegate* d) { delegate_ = d; }
 
   // Call this after updating a page action to notify clients about the changes.
   void PageActionStateChanged();
 
   // Requests application info for the specified page. This is an asynchronous
   // request. The delegate is notified by way of OnDidGetApplicationInfo when
   // 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
   // tab becomes an app-tab. WebContents does not listen for unload events for
   // the extension. It's up to consumers of WebContents to do that.
   //
   // NOTE: this should only be manipulated before the tab is added to a browser.
   // TODO(sky): resolve if this is the right way to identify an app tab. If it
   // is, than this should be passed in the constructor.
   void SetExtensionApp(const Extension* extension);
@@ skipping 102 matching lines @@
   ExtensionFunctionDispatcher extension_function_dispatcher_;
 
   // Used for loading extension_app_icon_.
   scoped_ptr<ImageLoadingTracker> extension_app_image_loader_;
 
   // Cached web app info data.
   WebApplicationInfo web_app_info_;
 
   TabContentsWrapper* wrapper_;
 
+  ObserverList<Observer> observers_;
+
   DISALLOW_COPY_AND_ASSIGN(ExtensionTabHelper);
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_TAB_HELPER_H_