Move Android user agent generation to native code

content/app/android/user_agent.cc

-// 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.
-
-#include "content/app/android/user_agent.h"
-
-#include "base/android/jni_android.h"
-#include "base/android/jni_string.h"
-#include "base/android/scoped_java_ref.h"
-#include "jni/UserAgent_jni.h"
-
-using base::android::AttachCurrentThread;
-using base::android::ScopedJavaLocalRef;
-using base::android::ConvertJavaStringToUTF8;
-using base::android::GetApplicationContext;
-
-namespace content {
-
-std::string GetUserAgentOSInfo() {
-  JNIEnv* env = AttachCurrentThread();
-  ScopedJavaLocalRef<jstring> os_info =
-      Java_UserAgent_getUserAgentOSInfo(env);
-  return ConvertJavaStringToUTF8(os_info);
-}
-
-bool RegisterUserAgent(JNIEnv* env) {
-  return RegisterNativesImpl(env);
-}
-
-}  // namespace content