Refactor fake Connection subclasses in proximity_auth/ tests to a single file.

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.
 
 import("//testing/test.gni")
 
 source_set("proximity_auth") {
   sources = [
     "authenticator.h",
     "bluetooth_connection.cc",
@@ skipping 60 matching lines @@
     "//net",
   ]
 }
 
 source_set("test_support") {
   testonly = true
 
   sources = [
     "device_to_device_responder_operations.cc",
     "device_to_device_responder_operations.h",
+    "fake_connection.cc",
+    "fake_connection.h",
     "mock_proximity_auth_client.cc",
     "mock_proximity_auth_client.h",
   ]
 
   deps = [
     "cryptauth:test_support",
     "//base",
     "//testing/gmock",
   ]
 }
@@ skipping 37 matching lines @@
 # 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",
   ]
 }