Make "webkit-patch pretty-diff" work under Cygwin

third_party/WebKit/Tools/Scripts/webkitpy/tool/steps/confirmdiff.py

 # Copyright (C) 2010 Google Inc. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 # notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 # copyright notice, this list of conditions and the following disclaimer
@@ skipping 34 matching lines @@
             Options.confirm,
         ]
 
     def _show_pretty_diff(self):
         if not self._tool.user.can_open_url():
             return None
 
         try:
             pretty_patch = PrettyPatch(self._tool.executive)
             pretty_diff_file = pretty_patch.pretty_diff_file(self.diff())
-            url = "file://%s" % urllib.quote(pretty_diff_file.name)
-            self._tool.user.open_url(url)
+            self._open_pretty_diff(pretty_diff_file.name)
+
             # We return the pretty_diff_file here because we need to keep the
             # file alive until the user has had a chance to confirm the diff.
             return pretty_diff_file
         except ScriptError, e:
             _log.warning("PrettyPatch failed.  :(")
         except OSError, e:
             _log.warning("PrettyPatch unavailable.")
 
+    def _open_pretty_diff(self, file_path):
+        if self._tool.platform.is_cygwin():
+            assert file_path.endswith('.html')
+            self._tool.executive.run_command(['cygstart', file_path])
+            return
+        url = "file://%s" % urllib.quote(file_path)
+        self._tool.user.open_url(url)
+
     def diff(self):
         changed_files = self._tool.scm().changed_files(self._options.git_commit)
         return self._tool.scm().create_patch(self._options.git_commit,
             changed_files=changed_files)
 
     def run(self, state):
         if not self._options.confirm:
             return
         pretty_diff_file = self._show_pretty_diff()
         if pretty_diff_file:
             diff_correct = self._tool.user.confirm("Was that diff correct?")
             pretty_diff_file.close()
             if not diff_correct:
                 self._exit(1)