Android: Remove unneeded RegisterNatives() calls

base/android/callback_android.cc

 // 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.
 
 #include "base/android/callback_android.h"
 
 #include "jni/Callback_jni.h"
 
 namespace base {
 namespace android {
 
 void RunCallbackAndroid(const JavaRef<jobject>& callback,
                         const JavaRef<jobject>& arg) {
   Java_Callback_onResultFromNativeV_JLO(base::android::AttachCurrentThread(),
                                         callback.obj(),
                                         arg.obj());
 }
 
 void RunCallbackAndroid(const JavaRef<jobject>& callback, bool arg) {
   Java_Callback_onResultFromNativeV_Z(base::android::AttachCurrentThread(),
                                       callback.obj(),
                                       static_cast<jboolean>(arg));
 }
 
 void RunCallbackAndroid(const JavaRef<jobject>& callback, int arg) {
   Java_Callback_onResultFromNativeV_I(base::android::AttachCurrentThread(),
                                       callback.obj(), arg);
 }
 
-bool RegisterCallbackAndroid(JNIEnv* env) {
-  return RegisterNativesImpl(env);
-}
-
 }  // namespace android
 }  // namespace base