Make `git cl description` work for Gerrit

Example change at https://chromium-review.googlesource.com/c/340430/.

R=tandrii@chromium.org
BUG=603207

Review URL: https://codereview.chromium.org/1917473002

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@300188 0039d316-1c4b-4281-b951-d872f2087c98

gerrit_util.py

@@ -541,6 +541,38 @@ def SubmitChange(host, change, wait_for_merge=True):
   return ReadHttpJsonResponse(conn, ignore_404=False)
 
 
+def SetCommitMessage(host, change, description):
+  """Updates a commit message."""
+  # First, edit the commit message in a draft.
+  path = 'changes/%s/edit:message' % change
+  body = {'message': description}
+  conn = CreateHttpConn(host, path, reqtype='PUT', body=body)
+  try:
+    ReadHttpResponse(conn, ignore_404=False)
+  except GerritError as e:
+    # On success, gerrit returns status 204; anything else is an error.
+    if e.http_status != 204:
+      raise
+  else:
+    raise GerritError(
+        'Unexpectedly received a 200 http status while editing message in '
+        'change %s' % change)
+
+  # And then publish it.
+  path = 'changes/%s/edit:publish' % change
+  conn = CreateHttpConn(host, path, reqtype='POST', body={})
+  try:
+    ReadHttpResponse(conn, ignore_404=False)
+  except GerritError as e:
+    # On success, gerrit returns status 204; anything else is an error.
+    if e.http_status != 204:
+      raise
+  else:
+    raise GerritError(
+        'Unexpectedly received a 200 http status while publishing message '
+        'change in %s' % change)
+
+
 def GetReviewers(host, change):
   """Get information about all reviewers attached to a change."""
   path = 'changes/%s/reviewers' % change

git_cl.py

@@ -2169,8 +2169,8 @@ class _GerritChangelistImpl(_ChangelistCodereviewBase):
     return gerrit_util.GetChangeDescriptionFromGitiles(url, current_rev)
 
   def UpdateDescriptionRemote(self, description):
-    # TODO(tandrii)
-    raise NotImplementedError()
+    gerrit_util.SetCommitMessage(self._GetGerritHost(), self.GetIssue(),
+                                 description)
 
   def CloseIssue(self):
     gerrit_util.AbandonChange(self._GetGerritHost(), self.GetIssue(), msg='')