Refactor WPT Export to ensure only one PR in flight at a time

third_party/WebKit/Tools/Scripts/webkitpy/w3c/chromium_commit.py

 # Copyright 2016 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.
 
+from webkitpy.common.webkit_finder import WebKitFinder
+
 
 class ChromiumCommit(object):
 
     def __init__(self, host, sha=None, position=None):
         """
         Args:
             host: A Host object
             sha: A Chromium commit SHA
             position: A string of the form:
                     'Cr-Commit-Position: refs/heads/master@{#431915}'
@@ skipping 29 matching lines @@
 
     def subject(self):
         return self.host.executive.run_command([
             'git', 'show', '--format=%s', '--no-patch', self.sha
         ])
 
     def body(self):
         return self.host.executive.run_command([
             'git', 'show', '--format=%b', '--no-patch', self.sha
         ])
+
+    def message(self):
+        """Returns a string with a commit's subject and body."""
+        return self.host.executive.run_command([
+            'git', 'show', '--format=%B', '--no-patch', self.sha
+        ])
+
+    def format_patch(self):
+        """Makes a patch with just changes in files in the WPT for a given commit."""
+        # TODO(jeffcarp): do not include expectations files
+        return self.host.executive.run_command([
+            'git', 'format-patch', '-1', '--stdout',
+            self.sha, self.absolute_chromium_wpt_dir()
+        ])
+
+    @memoized
+    def absolute_chromium_wpt_dir(self):
+        finder = WebKitFinder(self.host.filesystem)
+        return finder.path_from_webkit_base('LayoutTests', 'imported', 'wpt')