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

storage/common/fileapi/file_system_util.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/common/fileapi/file_system_util.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 
@@ skipping 20 matching lines @@
 
 // TODO(ericu): Consider removing support for '\', even on Windows, if possible.
 // There's a lot of test code that will need reworking, and we may have trouble
 // with base::FilePath elsewhere [e.g. DirName and other methods may also need
 // replacement].
 base::FilePath VirtualPath::BaseName(const base::FilePath& virtual_path) {
   base::FilePath::StringType path = virtual_path.value();
 
   // Keep everything after the final separator, but if the pathname is only
   // one character and it's a separator, leave it alone.
-  while (path.size() > 1 && base::FilePath::IsSeparator(path[path.size() - 1]))
+  while (path.size() > 1 && base::FilePath::IsSeparator(path.back()))
     path.resize(path.size() - 1);
   base::FilePath::StringType::size_type last_separator =
       path.find_last_of(base::FilePath::kSeparators);
   if (last_separator != base::FilePath::StringType::npos &&
       last_separator < path.size() - 1)
     path.erase(0, last_separator + 1);
 
   return base::FilePath(path);
 }
 
 base::FilePath VirtualPath::DirName(const base::FilePath& virtual_path) {
   typedef base::FilePath::StringType StringType;
   StringType  path = virtual_path.value();
 
   // The logic below is taken from that of base::FilePath::DirName, except
   // that this version never cares about '//' or drive-letters even on win32.
 
   // Strip trailing separators.
-  while (path.size() > 1 && base::FilePath::IsSeparator(path[path.size() - 1]))
+  while (path.size() > 1 && base::FilePath::IsSeparator(path.back()))
     path.resize(path.size() - 1);
 
   StringType::size_type last_separator =
       path.find_last_of(base::FilePath::kSeparators);
   if (last_separator == StringType::npos) {
     // path_ is in the current directory.
     return base::FilePath(base::FilePath::kCurrentDirectory);
   }
   if (last_separator == 0) {
     // path_ is in the root directory.
     return base::FilePath(path.substr(0, 1));
   }
   // path_ is somewhere else, trim the basename.
   path.resize(last_separator);
 
   // Strip trailing separators.
-  while (path.size() > 1 && base::FilePath::IsSeparator(path[path.size() - 1]))
+  while (path.size() > 1 && base::FilePath::IsSeparator(path.back()))
     path.resize(path.size() - 1);
 
   if (path.empty())
     return base::FilePath(base::FilePath::kCurrentDirectory);
 
   return base::FilePath(path);
 }
 
 void VirtualPath::GetComponents(
     const base::FilePath& path,
@@ skipping 413 matching lines @@
       return base::File::FILE_ERROR_ABORT;
     case net::ERR_ADDRESS_INVALID:
     case net::ERR_INVALID_URL:
       return base::File::FILE_ERROR_INVALID_URL;
     default:
       return base::File::FILE_ERROR_FAILED;
   }
 }
 
 }  // namespace storage