Make move_source_file.py work in blink again.

tools/git/move_source_file.py

 #!/usr/bin/env python
 # 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.
 
 """Moves C++ files to a new location, updating any include paths that point
 to them, and re-ordering headers as needed.  If multiple source files are
 specified, the destination must be a directory.  Updates include guards in
 moved header files.  Assumes Chromium coding style.
 
-Attempts to update paths used in .gyp(i) files, but does not reorder
-or restructure .gyp(i) files in any way.
+Attempts to update and reorder paths used in .gyp(i) files.
 
 Updates full-path references to files in // comments in source files.
 
 Must run in a git checkout, as it relies on git grep for a fast way to
 find files that reference the moved file.
 """
 
 
 import optparse
 import os
@@ skipping 183 matching lines @@
   # of the file plus one at the bottom for the comment on the #endif.
   if new_contents.count(new_guard) != 3:
     print ('WARNING: Could not successfully update include guard; perhaps '
            'old guard is not per style guide? You will have to update the '
            'include guard manually. (%s)' % new_path)
 
   with open(new_path, 'w') as f:
     f.write(new_contents)
 
 def main():
-  if not os.path.isdir('.git'):
-    print 'Fatal: You must run from the root of a git checkout.'
+  # We use "git rev-parse" to check if the script is run from a git checkout. It
+  # returns 0 even when run in the .git directory. We don't want people running
+  # this in the .git directory.
+  if (os.system('git rev-parse') != 0 or
+      os.path.basename(os.getcwd()) == '.git'):
+    print 'Fatal: You must run in a git checkout.'
     return 1
 
-  in_blink = os.getcwd().endswith("third_party/WebKit")
+  cwd = os.getcwd()
+  parent = os.path.dirname(cwd)
+  in_blink = (os.path.basename(parent) == 'third_party' and
+              os.path.basename(cwd) == 'WebKit')
 
   parser = optparse.OptionParser(usage='%prog FROM_PATH... TO_PATH')
   parser.add_option('--already_moved', action='store_true',
                     dest='already_moved',
                     help='Causes the script to skip moving the file.')
   parser.add_option('--no_error_for_non_source_file', action='store_false',
                     default='True',
                     dest='error_for_non_source_file',
                     help='Causes the script to simply print a warning on '
                     'encountering a non-source file rather than raising an '
@@ skipping 19 matching lines @@
       continue
     to_path = MakeDestinationPath(from_path, orig_to_path)
     if not opts.already_moved:
       MoveFile(from_path, to_path)
     UpdatePostMove(from_path, to_path, in_blink)
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main())