[Easy Unlock] Port the BluetoothConnection class to native code.

components/proximity_auth/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.
 
 static_library("proximity_auth") {
   sources = [
+    "bluetooth_connection.cc",
+    "bluetooth_connection.h",
     "bluetooth_util.cc",
     "bluetooth_util_chromeos.cc",
     "bluetooth_util.h",
     "connection.cc",
     "connection.h",
     "connection_observer.h",
     "proximity_auth_system.cc",
     "proximity_auth_system.h",
     "remote_device.h",
     "wire_message.cc",
     "wire_message.h",
   ]
 
   deps = [
     "//base",
     "//device/bluetooth",
     "//net",
   ]
 }
 
 source_set("unit_tests") {
   testonly = true
   sources = [
+    "bluetooth_connection_unittest.cc",
     "connection_unittest.cc",
     "proximity_auth_system_unittest.cc",
     "wire_message_unittest.cc",
   ]
 
   deps = [
     ":proximity_auth",
     "//base/test:test_support",
+    "//device/bluetooth:mocks",
     "//testing/gmock",
     "//testing/gtest",
   ]
 }
 
 # Note: This is a convenience target for ease of rapid iteration during
 # development. It is not executed on any try or build bots.
 test("proximity_auth_unittests") {
   sources = [
     "run_all_unittests.cc",
   ]
   
   deps = [
     ":unit_tests",
   ]
 }