Extract WebWidgetTestClient out of WebTestProxyBase and WebViewTestClient.

components/test_runner/web_test_interfaces.cc

Index: components/test_runner/web_test_interfaces.cc
diff --git a/components/test_runner/web_test_interfaces.cc b/components/test_runner/web_test_interfaces.cc
index 56108882daf6d9e2d3c2f30439947eda44de9765..8de868200d476689528112dbf47de5342972492b 100644
--- a/components/test_runner/web_test_interfaces.cc
+++ b/components/test_runner/web_test_interfaces.cc
@@ -17,6 +17,7 @@
 #include "components/test_runner/web_frame_test_client.h"
 #include "components/test_runner/web_test_proxy.h"
 #include "components/test_runner/web_view_test_client.h"
+#include "components/test_runner/web_widget_test_client.h"
 
 using namespace blink;
 
@@ -101,6 +102,13 @@ std::unique_ptr<WebViewTestClient> WebTestInterfaces::CreateWebViewTestClient(
       new WebViewTestClient(interfaces_->GetTestRunner(), web_test_proxy_base));
 }
 
+std::unique_ptr<WebWidgetTestClient>
+WebTestInterfaces::CreateWebWidgetTestClient(
+    WebTestProxyBase* web_test_proxy_base) {
+  return base::WrapUnique(new WebWidgetTestClient(interfaces_->GetTestRunner(),
+                                                  web_test_proxy_base));
+}
+
 std::vector<blink::WebView*> WebTestInterfaces::GetWindowList() {
   std::vector<blink::WebView*> result;
   for (WebTestProxyBase* proxy : interfaces_->GetWindowList())