Add presubmit for gn formatting

DEPS

 # This file is automatically processed to create .DEPS.git which is the file
 # that gclient uses under git.
 #
 # See http://code.google.com/p/chromium/wiki/UsingGit
 #
 # To test manually, run:
 #   python tools/deps2git/deps2git.py -o .DEPS.git -w <gclientdir>
 # where <gcliendir> is the absolute path to the directory containing the
 # .gclient file (the parent of 'src').
 #
@@ skipping 16 matching lines @@
   # the commit queue can handle CLs rolling Skia
   # and V8 without interference from each other.
   'v8_revision': '5e7bfaf5530837b94fa0c05189c0ab601e3a6355',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling ANGLE
   # and whatever else without interference from each other.
   "angle_revision": "746d0ea79208b514e95e626310bec513fa666ca4",
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling build tools
   # and whatever else without interference from each other.
-  'buildtools_revision': 'af2cab762e6de03ee53ba430a596ad98d5006778',
+  'buildtools_revision': '535aff24c308a715751028173e569596bcfe12a7',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling PDFium
   # and whatever else without interference from each other.
   'pdfium_revision': 'ef619d0562b39f30943cfdc4985a0df233d00e42',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling BoringSSL
   # and whatever else without interference from each other.
   'boringssl_revision': '00505ec2e1e4c3047b4f61a306f2ac1372fa7640',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling lss
@@ skipping 261 matching lines @@
     # corresponding .py files have already been deleted.
     'name': 'remove_stale_pyc_files',
     'pattern': 'src/tools/.*\\.py',
     'action': [
         'python',
         'src/tools/remove_stale_pyc_files.py',
         'src/tools',
     ],
   },
 ]