Add DEPS hooks to download gn/clang-format binaries on mac

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 238 matching lines @@
     'pattern': '.',
     'action': [ 'download_from_google_storage',
                 '--no_resume',
                 '--platform=linux*',
                 '--no_auth',
                 '--bucket', 'chromium-gn',
                 '-s', 'src/buildtools/linux64/gn.sha1',
     ],
   },
   {
+    'name': 'gn_mac',
+    'pattern': '.',
+    'action': [ 'download_from_google_storage',
+                '--no_resume',
+                '--platform=darwin',
+                '--no_auth',
+                '--bucket', 'chromium-gn',
+                '-s', 'src/buildtools/mac/gn.sha1',
+    ],
+  },
+  {
     'name': 'gn_win',
     'pattern': '.',
     'action': [ 'download_from_google_storage',
                 '--no_resume',
                 '--platform=win*',
                 '--no_auth',
                 '--bucket', 'chromium-gn',
                 '-s', 'src/buildtools/win/gn.exe.sha1',
     ],
   },
   # Pull clang-format binaries using checked-in hashes.
   {
     'name': 'clang_format_linux',
     'pattern': '.',
     'action': [ 'download_from_google_storage',
                 '--no_resume',
                 '--platform=linux*',
                 '--no_auth',
                 '--bucket', 'chromium-clang-format',
                 '-s', 'src/buildtools/linux64/clang-format.sha1',
     ],
   },
+  {
+    'name': 'clang_format_mac',
+    'pattern': '.',
+    'action': [ 'download_from_google_storage',
+                '--no_resume',
+                '--platform=darwin',
+                '--no_auth',
+                '--bucket', 'chromium-clang-format',
+                '-s', 'src/buildtools/mac/clang-format.sha1',
+    ],
+  },
   # Pull binutils for linux, enabled debug fission for faster linking /
   # debugging when used with clang on Ubuntu Precise.
   # https://code.google.com/p/chromium/issues/detail?id=352046
   {
     'name': 'binutils',
     'pattern': 'src/third_party/binutils',
     'action': [
         'python',
         'src/third_party/binutils/download.py',
     ],
@@ skipping 71 matching lines @@
     'name': 'dejavu-fonts',
     'pattern': '',
     'action': [ 'download_from_google_storage',
                 '--no_resume',
                 '--no_auth',
                 '--bucket', 'mojo/dejavu-fonts',
                 '-s', 'src/third_party/dejavu-fonts-ttf-2.34/ttf/DejaVuSansMono.ttf.sha1',
     ],
   },
 ]