gn: gyp_flag_compare.py de-escape command line properly

tools/gn/bin/gyp_flag_compare.py

 #!/usr/bin/env python
 
 # 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.
 
 """Given the output of -t commands from a ninja build for a gyp and GN generated
 build, report on differences between the command lines."""
 
 
 import os
+import shlex
 import subprocess
 import sys
 
 
 # Must be in src/.
 os.chdir(os.path.join(os.path.dirname(__file__), '..', '..', '..'))
 
 
 g_total_differences = 0
 
@@ skipping 47 matching lines @@
 
 
 def GetFlags(lines):
   """Turn a list of command lines into a semi-structured dict."""
   flags_by_output = {}
   for line in lines:
     # TODO(scottmg): Hacky way of getting only cc for now.
     if 'clang' not in line:
       continue
 
-    # TODO(scottmg): Proper escapes.
-    command_line = line.strip().split()[1:]
+    command_line = shlex.split(line.strip())[1:]
 
     output_name = FindAndRemoveArgWithValue(command_line, '-o')
     dep_name = FindAndRemoveArgWithValue(command_line, '-MF')
 
     NormalizeSymbolArguments(command_line)
 
     command_line = MergeSpacedArgs(command_line, '-Xclang')
 
     defines = [x for x in command_line if x.startswith('-D')]
     include_dirs = [x for x in command_line if x.startswith('-I')]
@@ skipping 127 matching lines @@
     print '\n'.join(sorted(files))
     print diff
 
   print 'Total differences:', g_total_differences
   # TODO(scottmg): Return failure on difference once we're closer to identical.
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main())