[Blimp Net] Client sends START_CONNECTION message

blimp/common/BUILD.gn

 # Copyright 2015 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("//testing/test.gni")
 
 component("blimp_common") {
   sources = [
     "blimp_common_export.h",
     "compositor/blimp_task_graph_runner.cc",
     "compositor/blimp_task_graph_runner.h",
     "create_blimp_message.cc",
     "create_blimp_message.h",
+    "protocol_version.cc",
+    "protocol_version.h",
   ]
 
   defines = [ "BLIMP_COMMON_IMPLEMENTATION=1" ]
 
   deps = [
     "//base",
     "//blimp/common/proto",
     "//cc",
     "//skia",
     "//ui/gfx/geometry",
     "//ui/gl",
   ]
 }
 
 source_set("unit_tests") {
   testonly = true
 
   sources = [
     "create_blimp_message_unittest.cc",
   ]
 
   deps = [
     ":blimp_common",
     "//blimp/common/proto",
     "//testing/gtest",
   ]
 }