Remove BrowserSignin, as it's not used anywhere.

chrome/test/base/testing_profile.cc

 // Copyright (c) 2011 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 "chrome/test/base/testing_profile.h"
 
 #include "build/build_config.h"
 
 #include "base/base_paths.h"
 #include "base/command_line.h"
@@ skipping 537 matching lines @@
 }
 
 void TestingProfile::SetQuotaManager(quota::QuotaManager* manager) {
   quota_manager_ = manager;
 }
 
 quota::QuotaManager* TestingProfile::GetQuotaManager() {
   return quota_manager_.get();
 }
 
-BrowserSignin* TestingProfile::GetBrowserSignin() {
-  return NULL;
-}
-
 bool TestingProfile::HasCreatedDownloadManager() const {
   return false;
 }
 
 net::URLRequestContextGetter* TestingProfile::GetRequestContext() {
   return request_context_.get();
 }
 
 net::URLRequestContextGetter* TestingProfile::GetRequestContextForRenderProcess(
     int renderer_child_id) {
@@ skipping 210 matching lines @@
 quota::SpecialStoragePolicy* TestingProfile::GetSpecialStoragePolicy() {
   return GetExtensionSpecialStoragePolicy();
 }
 
 void TestingProfile::DestroyWebDataService() {
   if (!web_data_service_.get())
     return;
 
   web_data_service_->Shutdown();
 }