Moving oauth code from host to base to allow code sharing between host and client.

remoting/host/setup/mock_oauth_client.cc

-// Copyright 2015 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 "remoting/host/setup/mock_oauth_client.h"
-
-namespace remoting {
-
-MockOAuthClient::MockOAuthClient(const std::string& user_email,
-                                 const std::string& refresh_token)
-    : user_email_(user_email), refresh_token_(refresh_token) {
-}
-
-MockOAuthClient::~MockOAuthClient() {
-}
-
-void MockOAuthClient::GetCredentialsFromAuthCode(
-    const gaia::OAuthClientInfo& oauth_client_info,
-    const std::string& auth_code,
-    bool need_user_email,
-    CompletionCallback on_done) {
-  on_done.Run(need_user_email ? user_email_ : "", refresh_token_);
-}
-
-}  // namespace remoting