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

third_party/WebKit/Tools/Scripts/webkitpy/w3c/local_wpt.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.
 
 """A utility class for interacting with a local checkout of the Web Platform Tests."""
 
 import logging
 
 from webkitpy.w3c.chromium_commit import ChromiumCommit
 
@@ skipping 54 matching lines @@
 
     def clean(self):
         self.run(['git', 'reset', '--hard', 'HEAD'])
         self.run(['git', 'clean', '-fdx'])
         self.run(['git', 'checkout', 'origin/master'])
 
     def all_branches(self):
         """Returns a list of local and remote branches."""
         return self.run(['git', 'branch', '-a']).splitlines()
 
-    def create_branch_with_patch(self, branch_name, message, patch):
+    def create_branch_with_patch(self, message, patch):
         """Commits the given patch and pushes to the upstream repo.
 
         Args:
-            branch_name: A name that is used for both the local branch
-                and the remote branch on github.
             message: Commit message string.
             patch: A patch that can be applied by git apply.
         """
         self.clean()
         all_branches = self.all_branches()
+        branch_name = 'chromium-export-try'
         remote_branch_name = 'remotes/github/%s' % branch_name
 
         if branch_name in all_branches:
             _log.info('Local branch %s already exists, deleting', branch_name)
             self.run(['git', 'branch', '-D', branch_name])
 
         if remote_branch_name in all_branches:
             _log.info('Remote branch %s already exists, deleting', branch_name)
             # TODO(jeffcarp): Investigate what happens when remote branch exists.
             self.run(['git', 'push', 'github', ':{}'.format(branch_name)])
 
         _log.info('Creating local branch %s', branch_name)
         self.run(['git', 'checkout', '-b', branch_name])
 
         # Remove Chromium WPT directory prefix.
         patch = patch.replace(CHROMIUM_WPT_DIR, '')
 
         # TODO(jeffcarp): Use git am -p<n> where n is len(CHROMIUM_WPT_DIR.split(/'))
         # or something not off-by-one.
         self.run(['git', 'apply', '-'], input=patch)
         self.run(['git', 'commit', '-am', message])
         self.run(['git', 'push', 'github', branch_name])
 
+        return branch_name
+
     def commits_behind_master(self, commit):
         """Returns the number of commits after the given commit on origin/master.
 
         This doesn't include the given commit, and this assumes that the given
         commit is on the the master branch.
         """
         return len(self.run([
             'git', 'rev-list', '{}..origin/master'.format(commit)
         ]).splitlines())