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

DEPS

Index: DEPS
diff --git a/DEPS b/DEPS
index a11b056fada6a38598f3941dc6a7bbe2f668999c..bc37e1ac578587ef96fb2ffea3d2572dad3b9223 100644
--- a/DEPS
+++ b/DEPS
@@ -256,6 +256,17 @@ hooks = [
     ],
   },
   {
+    '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',
@@ -278,6 +289,17 @@ hooks = [
                 '-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