Update SupportsUserData uses with unique_ptr.

content/browser/media/session/media_session_impl.h

 // Copyright 2015 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 CONTENT_BROWSER_MEDIA_SESSION_MEDIA_SESSION_IMPL_H_
 #define CONTENT_BROWSER_MEDIA_SESSION_MEDIA_SESSION_IMPL_H_
 
 #include <stddef.h>
 
 #include <map>
@@ skipping 49 matching lines @@
 // WebContents can only have one audio focus at a time, it will be Content in
 // case of Transient and Content audio focus are both requested.
 // TODO(thakis,mlamouri): MediaSessionImpl isn't CONTENT_EXPORT'd because it
 // creates complicated build issues with WebContentsUserData being a
 // non-exported template, see https://crbug.com/589840. As a result, the class
 // uses CONTENT_EXPORT for methods that are being used from tests.
 // CONTENT_EXPORT should be moved back to the class when the Windows build will
 // work with it.
 class MediaSessionImpl : public MediaSession,
                          public WebContentsObserver,
-                         protected WebContentsUserData<MediaSessionImpl> {
+                         public WebContentsUserData<MediaSessionImpl> {
  public:
   enum class State { ACTIVE, SUSPENDED, INACTIVE };
 
   // Returns the MediaSessionImpl associated to this WebContents. Creates one if
   // none is currently available.
   CONTENT_EXPORT static MediaSessionImpl* Get(WebContents* web_contents);
 
   ~MediaSessionImpl() override;
 
 #if defined(OS_ANDROID)
@@ skipping 232 matching lines @@
   ServicesMap services_;
   // The currently routed service (non-owned pointer).
   MediaSessionServiceImpl* routed_service_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaSessionImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_MEDIA_SESSION_MEDIA_SESSION_IMPL_H_