Depot tools: use the clang-format binaries that are now included

gn.py

Index: gn.py
diff --git a/gn.py b/gn.py
old mode 100644
new mode 100755
index 23521e3abb757aa12e824cf45f3422929fe04e10..067f42e0f1ce62ab43eb5ed3fc55a7747d4e0689
--- a/gn.py
+++ b/gn.py
@@ -12,55 +12,27 @@ binary. It will also automatically try to find the gn binary when run inside
 the chrome source tree, so users can just type "gn" on the command line
 (normally depot_tools is on the path)."""
 
+import gclient_utils
 import os
 import subprocess
 import sys
 
 
-class PlatformUnknownError(IOError):
-  pass
-
-
-def HasDotfile(path):
-  """Returns True if the given path has a .gn file in it."""
-  return os.path.exists(path + '/.gn')
-
-
-def FindSourceRootOnPath():
-  """Searches upward from the current directory for the root of the source
-  tree and returns the found path. Returns None if no source root could
-  be found."""
-  cur = os.getcwd()
-  while True:
-    if HasDotfile(cur):
-      return cur
-    up_one = os.path.dirname(cur)
-    if up_one == cur:
-      return None  # Reached the top of the directory tree
-    cur = up_one
-
-
 def RunGN(sourceroot):
   # The binaries in platform-specific subdirectories in src/tools/gn/bin.
-  gnpath = sourceroot + '/tools/gn/bin/'
-  if sys.platform in ('cygwin', 'win32'):
-    gnpath += 'win/gn.exe'
-  elif sys.platform.startswith('linux'):
-    gnpath += 'linux/gn'
-  elif sys.platform == 'darwin':
-    gnpath += 'mac/gn'
-  else:
-    raise PlatformUnknownError('Unknown platform for GN: ' + sys.platform)
-
+  gnpath = os.path.join(sourceroot,
+                        'tools', 'gn', 'bin', gclient_utils.GetMacWinOrLinux(),
+                        'gn' + gclient_utils.GetExeSuffix())
   return subprocess.call([gnpath] + sys.argv[1:])
 
 
 def main(args):
-  sourceroot = FindSourceRootOnPath()
+  sourceroot = gclient_utils.FindFileUpwards('.gn')
   if not sourceroot:
     print >> sys.stderr, '.gn file not found in any parent of the current path.'
     sys.exit(1)
   return RunGN(sourceroot)
 
+
 if __name__ == '__main__':
   sys.exit(main(sys.argv))