Update CL description by adding CQ_EXTRA_TRYBOTS for Telemetry changes.

This CL adds a post upload hook to add extra try bots list to the CL description in order to run
Telemetry benchmarks on Perf trybots in addtion to CQ trybots if the CL
contains any changes to Telemetry benchmarks.

BUG=462581

Review URL: https://codereview.chromium.org/1060763002

Cr-Commit-Position: refs/heads/master@{#327150}

codereview.settings

@@ -10,3 +10,4 @@ GITCL_PREDCOMMIT: http://src.chromium.org/viewvc/trunk/tools/depot_tools/git-cl-
 LINT_IGNORE_REGEX: webkit/api/.*
 PROJECT: chromium
 PENDING_REF_PREFIX: refs/pending/
+RUN_POST_UPLOAD_HOOK: True

tools/perf/PRESUBMIT.py

@@ -9,6 +9,7 @@
 """
 
 import os
+import re
 import sys
 
 
@@ -76,3 +77,49 @@ def CheckChangeOnCommit(input_api, output_api):
   report = []
   report.extend(_CommonChecks(input_api, output_api))
   return report
+
+
+def _IsBenchmarksModified(change):
+  """Checks whether CL contains any modification to Telemetry benchmarks."""
+  for affected_file in change.AffectedFiles():
+    affected_file_path = affected_file.LocalPath()
+    file_path, _ = os.path.splitext(affected_file_path)
+    if (os.path.join('tools', 'perf', 'benchmarks') in file_path or
+        os.path.join('tools', 'perf', 'measurements') in file_path):
+      return True
+  return False
+
+
+def PostUploadHook(cl, change, output_api):
+  """git cl upload will call this hook after the issue is created/modified.
+
+  This hook adds extra try bots list to the CL description in order to run
+  Telemetry benchmarks on Perf trybots in addtion to CQ trybots if the CL
+  contains any changes to Telemetry benchmarks.
+  """
+  benchmarks_modified = _IsBenchmarksModified(change)
+  rietveld_obj = cl.RpcServer()
+  issue = cl.issue
+  original_description = rietveld_obj.get_description(issue)
+  if not benchmarks_modified or re.search(
+     r'^CQ_EXTRA_TRYBOTS=.*', original_description, re.M | re.I):
+    return []
+
+  results = []
+  bots = [
+    'linux_perf_bisect',
+    'mac_perf_bisect',
+    'win_perf_bisect',
+    'android_nexus5_perf_bisect'
+  ]
+  bots = ['tryserver.chromium.perf:%s' % s for s in bots]
+  bots_string = ';'.join(bots)
+  description = original_description
+  description += '\nCQ_EXTRA_TRYBOTS=%s' % bots_string
+  results.append(output_api.PresubmitNotifyResult(
+      'Automatically added Perf trybots to run Telemetry benchmarks on CQ.'))
+
+  if description != original_description:
+   rietveld_obj.update_description(issue, description)
+
+  return results