Add ClientConfig proto, and JSON generation/parsing.

components/data_reduction_proxy/core/common/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//chrome/version.gni")
 
 static_library("common") {
   sources = [
     "data_reduction_proxy_bypass_type_list.h",
+    "data_reduction_proxy_client_config_parser.cc",
+    "data_reduction_proxy_client_config_parser.h",
     "data_reduction_proxy_config_values.h",
     "data_reduction_proxy_event_store.cc",
     "data_reduction_proxy_event_store.h",
     "data_reduction_proxy_headers.cc",
     "data_reduction_proxy_headers.h",
     "data_reduction_proxy_params.cc",
     "data_reduction_proxy_params.h",
     "data_reduction_proxy_pref_names.cc",
     "data_reduction_proxy_pref_names.h",
     "data_reduction_proxy_switches.cc",
     "data_reduction_proxy_switches.h",
   ]
 
   public_deps = [
     ":version_header",
   ]
   deps = [
     "//base",
+    "//components/data_reduction_proxy/proto:data_reduction_proxy_proto",
     "//net",
     "//url",
   ]
 }
 
 source_set("test_support") {
   testonly = true
   sources = [
     "data_reduction_proxy_headers_test_utils.cc",
     "data_reduction_proxy_headers_test_utils.h",
     "data_reduction_proxy_params_test_utils.cc",
     "data_reduction_proxy_params_test_utils.h",
   ]
 
   public_deps = [
     ":common",
   ]
   deps = [
     "//base",
     "//net",
     "//net:test_support",
     "//testing/gmock",
     "//testing/gtest",
   ]
 }
 
 source_set("unit_tests") {
   testonly = true
   sources = [
+    "data_reduction_proxy_client_config_parser_unittest.cc",
     "data_reduction_proxy_event_store_unittest.cc",
     "data_reduction_proxy_headers_unittest.cc",
     "data_reduction_proxy_params_unittest.cc",
   ]
 
   deps = [
     ":common",
     ":test_support",
     "//base",
     "//base/test:test_support",
+    "//components/data_reduction_proxy/proto:data_reduction_proxy_proto",
     "//net:test_support",
     "//testing/gtest",
   ]
 }
 
 process_version("version_header") {
   template_file = "version.h.in"
   output = "$target_gen_dir/version.h"
 }