Android: Remove unneeded RegisterNatives() calls

content/common/android/media_metadata_android.h

 // Copyright 2016 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_COMMON_ANDROID_MEDIA_METADATA_ANDROID_H_
 #define CONTENT_COMMON_ANDROID_MEDIA_METADATA_ANDROID_H_
 
 #include <jni.h>
 
 #include "base/android/scoped_java_ref.h"
 
 namespace content {
 
 struct MediaMetadata;
 
 class MediaMetadataAndroid {
  public:
   static base::android::ScopedJavaLocalRef<jobject> CreateJavaObject(
       JNIEnv* env, const MediaMetadata& metadata);
 
-  static bool Register(JNIEnv* env);
-
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(MediaMetadataAndroid);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_COMMON_ANDROID_MEDIA_METADATA_ANDROID_H_