Use container::back() and container::pop_back().

storage/browser/fileapi/file_system_url_request_job_factory.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 "storage/browser/fileapi/file_system_url_request_job_factory.h"
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "net/url_request/url_request.h"
 #include "storage/browser/fileapi/file_system_dir_url_request_job.h"
@@ skipping 34 matching lines @@
 
 FileSystemProtocolHandler::~FileSystemProtocolHandler() {}
 
 net::URLRequestJob* FileSystemProtocolHandler::MaybeCreateJob(
     net::URLRequest* request, net::NetworkDelegate* network_delegate) const {
   const std::string path = request->url().path();
 
   // If the path ends with a /, we know it's a directory. If the path refers
   // to a directory and gets dispatched to FileSystemURLRequestJob, that class
   // redirects back here, by adding a / to the URL.
-  if (!path.empty() && path[path.size() - 1] == '/') {
+  if (!path.empty() && path.back() == '/') {
     return new FileSystemDirURLRequestJob(
         request, network_delegate, storage_domain_, file_system_context_);
   }
   return new FileSystemURLRequestJob(
       request, network_delegate, storage_domain_, file_system_context_);
 }
 
 }  // anonymous namespace
 
 net::URLRequestJobFactory::ProtocolHandler* CreateFileSystemProtocolHandler(
     const std::string& storage_domain, FileSystemContext* context) {
   DCHECK(context);
   return new FileSystemProtocolHandler(storage_domain, context);
 }
 
 }  // namespace storage