Android: Remove unneeded RegisterNatives() calls

components/gcm_driver/instance_id/scoped_use_fake_instance_id_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 COMPONENTS_GCM_DRIVER_INSTANCE_ID_SCOPED_USE_FAKE_INSTANCE_ID_ANDROID_H_
 #define COMPONENTS_GCM_DRIVER_INSTANCE_ID_SCOPED_USE_FAKE_INSTANCE_ID_ANDROID_H_
 
 #include <jni.h>
 
 #include "base/macros.h"
 
 namespace instance_id {
 
 // Tests depending on InstanceID must use this, to avoid hitting the
 // network/disk. Also clears cached InstanceIDs when constructed/destructed.
 class ScopedUseFakeInstanceIDAndroid {
  public:
   ScopedUseFakeInstanceIDAndroid();
   ~ScopedUseFakeInstanceIDAndroid();
 
-  // Register JNI methods.
-  static bool RegisterJni(JNIEnv* env);
-
  private:
   bool previous_value_;
 
   DISALLOW_COPY_AND_ASSIGN(ScopedUseFakeInstanceIDAndroid);
 };
 
 }  // namespace instance_id
 
 #endif  // COMPONENTS_GCM_DRIVER_INSTANCE_ID_SCOPED_USE_FAKE_INSTANCE_ID_ANDROID_H_