Add jsoncpp as third_party dep

DEPS

@@ -14,6 +14,9 @@ vars = {
   # Current revision of glslang, the Khronos SPIRV compiler.
   'glslang_revision': '1ea8f595f9a9ebd938fe9e5f15ae469c7d6ebabc',
 
+  # Current revision of jsoncpp, an open-source json parser.
+  'jsoncpp_revision': '93ba642c636309a3195d6da6c11ba82f69ef45ed',
+
   # Current revision fo the SPIRV-Headers Vulkan support library.
   'spirv_headers_revision': 'ff684ffc6a35d2a58f0f63108877d0064ea33feb',
 
@@ -74,6 +77,10 @@ deps = {
     'condition': 'not build_with_chromium',
   },
 
+  '{angle_root}/third_party/jsoncpp/src': {
+    'url': '{android_git}/platform/external/jsoncpp@{jsoncpp_revision}',
+  },
+
   '{angle_root}/third_party/spirv-headers/src': {
     'url': '{android_git}/platform/external/shaderc/spirv-headers@{spirv_headers_revision}',
   },

third_party/jsoncpp/README.angle

+Name: JsonCpp
+Short Name: JsonCpp
+Version: N/A
+URL: https://github.com/open-source-parsers/jsoncpp
+SOURCE CODE: git clone https://android.googlesource.com/platform/external/jsoncpp
+Date: 08/28/2018
+Revision: 93ba642c636309a3195d6da6c11ba82f69ef45ed
+Security Critical: no
+License: MIT
+License File: LICENSE
+
+Description:
+JsonCpp is a C++ library that allows manipulating JSON values, including serialization and
+deserialization to and from strings. It can also preserve existing comment in unserialization/
+serialization steps, making it a convenient format to store user input files.
+