Remove page IDs from three WebContentsObserver APIs that don't need it.

apps/app_window.h

 // Copyright 2014 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 APPS_APP_WINDOW_H_
 #define APPS_APP_WINDOW_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "chrome/browser/extensions/extension_icon_image.h"
@@ skipping 387 matching lines @@
                                    const content::NativeWebKeyboardEvent& event)
       OVERRIDE;
   virtual void RequestToLockMouse(content::WebContents* web_contents,
                                   bool user_gesture,
                                   bool last_unlocked_by_target) OVERRIDE;
   virtual bool PreHandleGestureEvent(content::WebContents* source,
                                      const blink::WebGestureEvent& event)
       OVERRIDE;
 
   // content::WebContentsObserver implementation.
-  virtual void DidFirstVisuallyNonEmptyPaint(int32 page_id) OVERRIDE;
+  virtual void DidFirstVisuallyNonEmptyPaint() OVERRIDE;
 
   // content::NotificationObserver implementation.
   virtual void Observe(int type,
                        const content::NotificationSource& source,
                        const content::NotificationDetails& details) OVERRIDE;
 
   // web_modal::WebContentsModalDialogManagerDelegate implementation.
   virtual void SetWebContentsBlocked(content::WebContents* web_contents,
                                      bool blocked) OVERRIDE;
   virtual bool IsWebContentsVisible(content::WebContents* web_contents)
@@ skipping 108 matching lines @@
   // reinstated when the window exits fullscreen and moves away from the
   // taskbar.
   bool cached_always_on_top_;
 
   DISALLOW_COPY_AND_ASSIGN(AppWindow);
 };
 
 }  // namespace apps
 
 #endif  // APPS_APP_WINDOW_H_