Add implementations of mojo::{Run,Terminate}[Main]Application() for "chromium".

mojo/application/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.
 
 source_set("application") {
   sources = [
     "application_runner_chromium.cc",
     "application_runner_chromium.h",
+    "run_application.cc",
   ]
 
   public_deps = [
     "//mojo/public/cpp/application",
   ]
   deps = [
     "//base",
+    "//mojo/environment:chromium",
     "//mojo/message_pump",
     "//mojo/public/cpp/system",
-    "//mojo/environment:chromium",
   ]
 }
 
 source_set("content_handler") {
   sources = [
     "content_handler_factory.cc",
     "content_handler_factory.h",
   ]
   deps = [
     ":application",
@@ skipping 16 matching lines @@
     "//mojo/public/cpp/application:test_support",
   ]
   deps = [
     "//base",
     "//base/test:test_config",
     "//mojo/environment:chromium",
     "//mojo/public/cpp/application",
     "//mojo/public/cpp/system",
   ]
 }