tryserver recipe_module: Add get_tags.

recipe_modules/git_cl/api.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 recipe_engine import recipe_api
 
 class GitClApi(recipe_api.RecipeApi):
   def __call__(self, subcmd, args, name=None, **kwargs):
     if not name:
       name = 'git_cl ' + subcmd
+
+    if kwargs.get('suffix'):
+      name = name + ' (%s)' % kwargs.pop('suffix')
+
     if 'cwd' not in kwargs:
       kwargs['cwd'] = (self.c and self.c.repo_location) or None
 
     return self.m.step(
-        name, [self.package_repo_resource('git_cl.py')] + args, **kwargs)
+        name, [self.package_repo_resource('git_cl.py'), subcmd] + args,
+        **kwargs)
 
-  def get_description(self, **kwargs):
-    return self('description', ['-d'], stdout=self.m.raw_io.output(), **kwargs)
+  def get_description(self, patch=None, codereview=None, **kwargs):
+    args = ['-d']
+    if patch or codereview:
+      assert patch and codereview, "Both patch and codereview must be provided"
+      args.append('--%s' % codereview)
+      args.append(patch)
 
-  def set_description(self, description, **kwargs):
+    return self('description', args, stdout=self.m.raw_io.output(), **kwargs)
+
+  def set_description(self, description, patch=None, codereview=None, **kwargs):
+    args = ['-n', '-']
+    if patch or codereview:
+      assert patch and codereview, "Both patch and codereview must be provided"
+      args.append(patch)
+      args.append('--%s' % codereview)
+
     return self(
-        'description', ['-n', '-'],
-        stdout=self.m.raw_io.output(),
+        'description', args, stdout=self.m.raw_io.output(),
         stdin=self.m.raw_io.input(data=description),
         name='git_cl set description', **kwargs)