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

third_party/SPIRV-Tools/LICENSE

Index: third_party/SPIRV-Tools/LICENSE
diff --git a/media/test/data/COPYING b/third_party/SPIRV-Tools/LICENSE
similarity index 79%
copy from media/test/data/COPYING
copy to third_party/SPIRV-Tools/LICENSE
index 9354043554571537ad28a13f4b1db353db3f876d..8b2e82136ba8c37c8b76a77f37cc35ad4d1b12a6 100644
--- a/media/test/data/COPYING
+++ b/third_party/SPIRV-Tools/LICENSE
@@ -1,5 +1,4 @@
-npot-video.h264, red-green.h264:
-Copyright (c) 2012 The Khronos Group Inc.
+Copyright (c) 2015-2016 The Khronos Group Inc.
 
 Permission is hereby granted, free of charge, to any person obtaining a
 copy of this software and/or associated documentation files (the
@@ -12,6 +11,11 @@ the following conditions:
 The above copyright notice and this permission notice shall be included
 in all copies or substantial portions of the Materials.
 
+MODIFICATIONS TO THIS FILE MAY MEAN IT NO LONGER ACCURATELY REFLECTS
+KHRONOS STANDARDS. THE UNMODIFIED, NORMATIVE VERSIONS OF KHRONOS
+SPECIFICATIONS AND HEADER INFORMATION ARE LOCATED AT
+   https://www.khronos.org/registry/
+
 THE MATERIALS ARE PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.