Add git cl format presubmit warning for extension and apps.

apps/PRESUBMIT.py

Index: apps/PRESUBMIT.py
diff --git a/ui/gl/PRESUBMIT.py b/apps/PRESUBMIT.py
similarity index 60%
copy from ui/gl/PRESUBMIT.py
copy to apps/PRESUBMIT.py
index 1e529b45f02900529b692cb5f1def7ffacd8d9bc..60ce8b4f4290b6f6b56ce0db442ebec972ff7669 100644
--- a/ui/gl/PRESUBMIT.py
+++ b/apps/PRESUBMIT.py
@@ -2,16 +2,13 @@
 # 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 ui/gl/.
+"""Presubmit script for extensions and apps.
 
 See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
 for more details about the presubmit API built into depot_tools.
 """
 
-def GetPreferredTrySlaves(project, change):
-  return [
-    'linux_gpu',
-    'mac_gpu',
-    'mac_gpu_retina',
-    'win_gpu',
-  ]
+def CheckChangeOnUpload(input_api, output_api):
+  results = []
+  results += input_api.canned_checks.CheckPatchFormatted(input_api, output_api)
+  return results