Roll gyp to bac4680ec9a5c55ab692490b6732999648ecf1e9.

DEPS

 # This file is used to manage the dependencies of the Chromium src repo. It is
 # used by gclient to determine what version of each dependency to check out, and
 # where.
 #
 # For more information, please refer to the official documentation:
 #   https://sites.google.com/a/chromium.org/dev/developers/how-tos/get-the-code
 #
 # When adding a new dependency, please update the top-level .gitignore file
 # to list the dependency's destination directory.
 #
@@ skipping 133 matching lines @@
   'src/third_party/hunspell_dictionaries':
    Var('chromium_git') + '/chromium/deps/hunspell_dictionaries.git' + '@' + 'dc6e7c25bf47cbfb466e0701fd2728b4a12e79d5',
 
   'src/third_party/leveldatabase/src':
     Var('chromium_git') + '/external/leveldb.git' + '@' + 'a7bff697baa062c8f6b8fb760eacf658712b611a',
 
   'src/third_party/snappy/src':
     Var('chromium_git') + '/external/snappy.git' + '@' + '762bb32f0c9d2f31ba4958c7c0933d22e80c20bf',
 
   'src/tools/gyp':
-    Var('chromium_git') + '/external/gyp.git' + '@' + 'c61b0b35c8396bfd59efc6cfc11401d912b0f510',
+    Var('chromium_git') + '/external/gyp.git' + '@' + 'bac4680ec9a5c55ab692490b6732999648ecf1e9',
 
   'src/tools/swarming_client':
    Var('chromium_git') + '/external/swarming.client.git' + '@' +  Var('swarming_revision'),
 
   'src/v8':
     Var('chromium_git') + '/v8/v8.git' + '@' +  Var('v8_revision'),
 
   'src/native_client':
    Var('chromium_git') + '/native_client/src/native_client.git' + '@' + Var('nacl_revision'),
 
@@ skipping 791 matching lines @@
   {
     # A change to a .gyp, .gypi, or to GYP itself should run the generator.
     'name': 'gyp',
     'pattern': '.',
     'action': ['python', 'src/build/gyp_chromium', '--running-as-hook'],
   },
 ]
 
 # ANGLE manages DEPS that it also owns the build files for, such as dEQP.
 recursedeps = [("src/third_party/angle", "DEPS.chromium")]