tools/gn: Convert for loops to use the new range-based loops in C++11.

tools/gn/exec_process.cc

 // Copyright 2014 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 "base/command_line.h"
 #include "base/files/file_util.h"
 #include "base/logging.h"
 #include "base/process/kill.h"
 #include "base/process/launch.h"
 #include "base/process/process.h"
@@ skipping 176 matching lines @@
 
         fd_shuffle1.push_back(
             base::InjectionArc(out_write.get(), STDOUT_FILENO, true));
         fd_shuffle1.push_back(
             base::InjectionArc(err_write.get(), STDERR_FILENO, true));
         fd_shuffle1.push_back(
             base::InjectionArc(dev_null, STDIN_FILENO, true));
         // Adding another element here? Remeber to increase the argument to
         // reserve(), above.
 
-        for (size_t i = 0; i < fd_shuffle1.size(); ++i)
-          fd_shuffle2.push_back(fd_shuffle1[i]);
+        for (const auto& elem : fd_shuffle1)
+          fd_shuffle2.push_back(elem);
 
         if (!ShuffleFileDescriptors(&fd_shuffle1))
           _exit(127);
 
         base::SetCurrentDirectory(startup_dir);
 
         // TODO(brettw) the base version GetAppOutput does a
         // CloseSuperfluousFds call here. Do we need this?
 
         for (size_t i = 0; i < argv.size(); i++)
@@ skipping 31 matching lines @@
         return process.WaitForExit(exit_code);
       }
   }
 
   return false;
 }
 #endif
 
 }  // namespace internal