Roll src/tools/gyp/ 4ec6c4e3a..6ea68631c (3 commits).

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 136 matching lines @@
   'src/third_party/safe_browsing/testing':
     Var('chromium_git') + '/external/google-safe-browsing/testing.git' + '@' + '9d7e8064f3ca2e45891470c9b5b1dce54af6a9d6',
 
   'src/third_party/leveldatabase/src':
     Var('chromium_git') + '/external/leveldb.git' + '@' + '7306ef856a91e462a73ff1832c1fa8771008ba36',
 
   'src/third_party/snappy/src':
     Var('chromium_git') + '/external/snappy.git' + '@' + '762bb32f0c9d2f31ba4958c7c0933d22e80c20bf',
 
   'src/tools/gyp':
-    Var('chromium_git') + '/external/gyp.git' + '@' + '4ec6c4e3a94bd04a6da2858163d40b2429b8aad1',
+    Var('chromium_git') + '/external/gyp.git' + '@' + '6ea68631cdabab9b7c5257657567a785a261692e',
 
   '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 685 matching lines @@
     'pattern': '\\.sha1',
     'action': ['python', 'src/third_party/instrumented_libraries/scripts/download_binaries.py'],
   },
   {
     # A change to a .gyp, .gypi, or to GYP itself should run the generator.
     'name': 'gyp',
     'pattern': '.',
     'action': ['python', 'src/build/gyp_chromium'],
   },
 ]