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

google_apis/gaia/fake_gaia.cc

 // Copyright (c) 2013 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 "google_apis/gaia/fake_gaia.h"
 
 #include <utility>
 #include <vector>
 
 #include "base/base_paths.h"
@@ skipping 67 matching lines @@
   if (iter != request.headers.end()) {
     for (const std::string& cookie_line :
          base::SplitString(iter->second, " ", base::TRIM_WHITESPACE,
                            base::SPLIT_WANT_ALL)) {
       std::vector<std::string> name_value = base::SplitString(
           cookie_line, "=", base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);
       if (name_value.size() != 2)
         continue;
 
       std::string value = name_value[1];
-      if (value.size() && value[value.size() - 1] == ';')
+      if (value.size() && value.back() == ';')
         value = value.substr(0, value.size() -1);
 
       result.insert(std::make_pair(name_value[0], value));
     }
   }
   return result;
 }
 
 // Extracts the |access_token| from authorization header of |request|.
 bool GetAccessToken(const HttpRequest& request,
@@ skipping 734 matching lines @@
   url = net::AppendQueryParameter(url, "RelayState",
                                   GaiaUrls::GetInstance()
                                       ->gaia_url()
                                       .Resolve(kDummySAMLContinuePath)
                                       .spec());
   std::string redirect_url = url.spec();
   http_response->set_code(net::HTTP_TEMPORARY_REDIRECT);
   http_response->AddCustomHeader("Google-Accounts-SAML", "Start");
   http_response->AddCustomHeader("Location", redirect_url);
 }