Add a new CldDataSource class that can be queried at runtime.

components/translate/content/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("//build/config/features.gni")
 
 static_library("common") {
   sources = [
     "translate_messages.cc",
     "translate_messages.h",
+    "cld_data_source.h",
   ]
 
   deps = [
     "//base",
     "//components/translate/core/common",
     "//components/translate/core/language_detection",
     "//content/public/common",
     "//ipc",
   ]
 
   if (cld2_data_source == "standalone" || cld2_data_source == "component") {
     sources += [
       "data_file_cld_data_provider_messages.cc",
       "data_file_cld_data_provider_messages.h",
     ]
   }
+  if (cld2_data_source == "standalone") {
+    sources += [ "standalone_cld_data_source.cc" ]
+  }
+  if (cld2_data_source == "component") {
+    sources += [ "component_cld_data_source.cc" ]
+  }
+  if (cld2_data_source == "static") {
+    sources += [ "static_cld_data_source.cc" ]
+  }
 }