Automatically add a docs preview link and NOTRY=true when there are only docs changes

PRESUBMIT.py

 # Copyright (c) 2013 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.
 
 
 """Top-level presubmit script for Skia.
 
 See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
 for more details about the presubmit API built into gcl.
 """
 
 import fnmatch
 import os
 import re
+import subprocess
 import sys
 import traceback
 
 
 REVERT_CL_SUBJECT_PREFIX = 'Revert '
 
 SKIA_TREE_STATUS_URL = 'http://skia-tree-status.appspot.com'
 
 # Please add the complete email address here (and not just 'xyz@' or 'xyz').
 PUBLIC_API_OWNERS = (
     'reed@chromium.org',
     'reed@google.com',
     'bsalomon@chromium.org',
     'bsalomon@google.com',
     'djsollen@chromium.org',
     'djsollen@google.com',
 )
 
 AUTHORS_FILE_NAME = 'AUTHORS'
 
+DOCS_PREVIEW_URL = 'https://skia.org/?cl='
+
 
 def _CheckChangeHasEol(input_api, output_api, source_file_filter=None):
   """Checks that files end with atleast one \n (LF)."""
   eof_files = []
   for f in input_api.AffectedSourceFiles(source_file_filter):
     contents = input_api.ReadFile(f, 'rb')
     # Check that the file ends in atleast one newline character.
     if len(contents) > 1 and contents[-1:] != '\n':
       eof_files.append(f.LocalPath())
 
@@ skipping 187 matching lines @@
           break
 
   if not lgtm_from_owner:
     results.append(
         output_api.PresubmitError(
             'Since the CL is editing public API, you must have an LGTM from '
             'one of: %s' % str(PUBLIC_API_OWNERS)))
   return results
 
 
+def PostUploadHook(cl, change, output_api):
+  """git cl upload will call this hook after the issue is created/modified.
+
+  This hook does the following:
+  * Adds a link to preview docs changes if there are any docs changes in the CL.
+  * Adds 'NOTRY=true' if the CL contains only docs changes.
+  """
+
+  results = []
+  atleast_one_docs_change = False
+  all_docs_changes = True
+  for affected_file in change.AffectedFiles():
+    affected_file_path = affected_file.LocalPath()
+    file_path, _ = os.path.splitext(affected_file_path)
+    if 'site' == file_path.split(os.path.sep)[0]:
+      atleast_one_docs_change = True
+    else:
+      all_docs_changes = False
+    if atleast_one_docs_change and not all_docs_changes:
+      break
+
+  issue = cl.issue
+  rietveld_obj = cl.RpcServer()
+  if issue and rietveld_obj:
+    original_description = rietveld_obj.get_description(issue)
+    new_description = original_description
+
+    # If the change includes only doc changes then add NOTRY=true in the
+    # CL's description if it does not exist yet.
+    if all_docs_changes and not re.search(
+        r'^NOTRY=true$', original_description, re.M | re.I):
+      new_description += '\nNOTRY=true'
+      results.append(
+          output_api.PresubmitNotifyResult(
+              'This change has only doc changes. Automatically added '
+              '\'NOTRY=true\' to the CL\'s description'))
+
+    # If there is atleast one docs change then add preview link in the CL's
+    # description if it does not already exist there.
+    if atleast_one_docs_change and not re.search(
+        r'^DOCS_PREVIEW=.*', original_description, re.M | re.I):
+      # Automatically add a link to where the docs can be previewed.
+      new_description += '\nDOCS_PREVIEW= %s%s' % (DOCS_PREVIEW_URL, issue)
+      results.append(
+          output_api.PresubmitNotifyResult(
+              'Automatically added a link to preview the docs changes to the '
+              'CL\'s description'))
+
+    # If the description has changed update it.
+    if new_description != original_description:
+      rietveld_obj.update_description(issue, new_description)
+
+    return results
+
+
 def CheckChangeOnCommit(input_api, output_api):
   """Presubmit checks for the change on commit.
 
   The following are the presubmit checks:
   * Check change has one and only one EOL.
   * Ensures that the Skia tree is open in
     http://skia-tree-status.appspot.com/. Shows a warning if it is in 'Caution'
     state and an error if it is in 'Closed' state.
   """
   results = []
   results.extend(_CommonChecks(input_api, output_api))
   results.extend(
       _CheckTreeStatus(input_api, output_api, json_url=(
           SKIA_TREE_STATUS_URL + '/banner-status?format=json')))
   results.extend(_CheckLGTMsForPublicAPI(input_api, output_api))
   results.extend(_CheckOwnerIsInAuthorsFile(input_api, output_api))
   return results