base: Remove unneeded RegisterNatives() calls on Android

base/android/callback_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 BASE_ANDROID_CALLBACK_ANDROID_H_
 #define BASE_ANDROID_CALLBACK_ANDROID_H_
 
 #include <jni.h>
 
 #include "base/android/scoped_java_ref.h"
 #include "base/base_export.h"
 
 namespace base {
 namespace android {
 
 // Runs the given |callback| with the specified |arg|.
 void BASE_EXPORT RunCallbackAndroid(const JavaRef<jobject>& callback,
                                     const JavaRef<jobject>& arg);
 
 // Runs the given |callback| with the specified |arg|.
 void BASE_EXPORT RunCallbackAndroid(const JavaRef<jobject>& callback,
                                     bool arg);
 
 // Runs the given |callback| with the specified |arg|.
 void BASE_EXPORT RunCallbackAndroid(const JavaRef<jobject>& callback, int arg);
 
-// JNI registration boilerplate.
-bool RegisterCallbackAndroid(JNIEnv* env);
-
 }  // namespace android
 }  // namespace base
 
 #endif  // BASE_ANDROID_CALLBACK_ANDROID_H_