Extract WebWidgetTestClient out of WebTestProxyBase and WebViewTestClient.

components/test_runner/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("//build/config/features.gni")
 import("//build/config/ui.gni")
 if (is_android) {
   import("//build/config/android/config.gni")
 }
 
@@ skipping 79 matching lines @@
     "web_task.cc",
     "web_task.h",
     "web_test_delegate.h",
     "web_test_interfaces.cc",
     "web_test_interfaces.h",
     "web_test_proxy.cc",
     "web_test_proxy.h",
     "web_test_runner.h",
     "web_view_test_client.cc",
     "web_view_test_client.h",
+    "web_widget_test_client.cc",
+    "web_widget_test_client.h",
   ]
 
   # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
   configs += [ "//build/config/compiler:no_size_t_to_int_warning" ]
 
   deps = [
     ":resources",
     "//base:base",
     "//base:i18n",
     "//cc",
@@ skipping 91 matching lines @@
     if (is_mac) {
       libs = [ "AppKit.framework" ]
     }
 
     deps = [
       "//build/config/sanitizers:deps",
       "//build/win:default_exe_manifest",
     ]
   }
 }