Use process/control messages (instead of RVH messages) for layout tests.

content/shell/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")
 import("//build/config/sanitizers/sanitizers.gni")
 import("//build/config/ui.gni")
 import("//build/config/win/console_app.gni")
 import("//build/config/win/manifest.gni")
 import("//media/media_options.gni")
@@ skipping 134 matching lines @@
     "browser/shell_resource_dispatcher_host_delegate.cc",
     "browser/shell_resource_dispatcher_host_delegate.h",
     "browser/shell_speech_recognition_manager_delegate.cc",
     "browser/shell_speech_recognition_manager_delegate.h",
     "browser/shell_url_request_context_getter.cc",
     "browser/shell_url_request_context_getter.h",
     "browser/shell_web_contents_view_delegate.h",
     "browser/shell_web_contents_view_delegate_android.cc",
     "browser/shell_web_contents_view_delegate_creator.h",
     "browser/shell_web_contents_view_delegate_mac.mm",
-    "common/layout_test/layout_test_content_client.cc",
-    "common/layout_test/layout_test_content_client.h",
     "common/layout_test/layout_test_messages.cc",
     "common/layout_test/layout_test_messages.h",
     "common/layout_test/layout_test_switches.cc",
     "common/layout_test/layout_test_switches.h",
     "common/leak_detection_result.h",
     "common/shell_content_client.cc",
     "common/shell_content_client.h",
     "common/shell_messages.cc",
     "common/shell_messages.h",
     "common/shell_origin_trial_policy.cc",
@@ skipping 574 matching lines @@
       "{{bundle_resources_dir}}/{{source_file_part}}",
     ]
   }
 }
 
 mojom("mojo_bindings") {
   sources = [
     "common/layout_test/layout_test_bluetooth_fake_adapter_setter.mojom",
   ]
 }