Added shaderc, glslang, and SPIRV-Tools to third_party.

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 110 matching lines @@
 
   'src/sdch/open-vcdiff':
    Var('chromium_git') + '/external/github.com/google/open-vcdiff.git' + '@' + '21d7d0b9c3d0c3ccbdb221c85ae889373f0a2a58',
 
   'src/testing/gtest':
    Var('chromium_git') + '/external/github.com/google/googletest.git' + '@' + '6f8a66431cb592dad629028a50b3dd418a408c87',
 
   'src/testing/gmock':
    Var('chromium_git') + '/external/googlemock.git' + '@' + '0421b6f358139f02e102c9c332ce19a33faf75be', # from svn revision 566
 
+   'src/third_party/glslang/src':
+   Var('chromium_git') + '/external/github.com/google/glslang.git' + '@' + '210c6bf4d8119dc5f8ac21da2d4c87184f7015e0',
+
+   'src/third_party/shaderc/src':
+   Var('chromium_git') + '/external/github.com/google/shaderc.git' + '@' + 'cd8793c34907073025af2622c28bcee64e9879a4',
+
+   'src/third_party/SPIRV-Tools/src':
+   Var('chromium_git') + '/external/github.com/KhronosGroup/SPIRV-Tools.git' + '@' + '9166854ac93ef81b026e943ccd230fed6c8b8d3c',
+
   'src/third_party/angle':
    Var('chromium_git') + '/angle/angle.git' + '@' +  Var('angle_revision'),
 
   'src/third_party/colorama/src':
    Var('chromium_git') + '/external/colorama.git' + '@' + '799604a1041e9b3bc5d2789ecbd7e8db2e18e6b8',
 
   'src/third_party/icu':
    Var('chromium_git') + '/chromium/deps/icu.git' + '@' + 'c291cde264469b20ca969ce8832088acb21e0c48',
 
   'src/third_party/hunspell_dictionaries':
@@ skipping 705 matching lines @@
                'src/build/android/download_doclava.py',
     ],
   },
   {
     # 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'],
   },
 ]