Make MediaSession a runtime-enabled feature on Desktop.

content/public/browser/web_contents.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 CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_H_
 #define CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_H_
 
 #include <stdint.h>
 
 #include <set>
@@ skipping 678 matching lines @@
   // browser fullscreen.
   virtual void ExitFullscreen(bool will_cause_resize) = 0;
 
   // Unblocks requests from renderer for a newly created window. This is
   // used in showCreatedWindow() or sometimes later in cases where
   // delegate->ShouldResumeRequestsForCreatedWindow() indicated the requests
   // should not yet be resumed. Then the client is responsible for calling this
   // as soon as they are ready.
   virtual void ResumeLoadingCreatedWebContents() = 0;
 
-#if defined(OS_ANDROID)
   // Requests to resume the current media session.
   virtual void ResumeMediaSession() = 0;
   // Requests to suspend the current media session.
   virtual void SuspendMediaSession() = 0;
   // Requests to stop the current media session.
   virtual void StopMediaSession() = 0;
 
+#if defined(OS_ANDROID)
   CONTENT_EXPORT static WebContents* FromJavaWebContents(
       jobject jweb_contents_android);
   virtual base::android::ScopedJavaLocalRef<jobject> GetJavaWebContents() = 0;
 #elif defined(OS_MACOSX)
   // Allowing other views disables optimizations which assume that only a single
   // WebContents is present.
   virtual void SetAllowOtherViews(bool allow) = 0;
 
   // Returns true if other views are allowed, false otherwise.
   virtual bool GetAllowOtherViews() = 0;
 #endif  // OS_ANDROID
 
  private:
   // This interface should only be implemented inside content.
   friend class WebContentsImpl;
   WebContents() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_H_