[MR integration test] Speculative fix for Dialog_Basic test on Mac.

Remove the domAutomationController.send call in the scripts to dispatch
mouse events. Since the returned value isn't consumed by the C++ code,
we shouldn't call domAutomationController.send.

Bug: 742443
Change-Id: Ibd54468a68a96dd324897239b6196c1896906891
Reviewed-on: https://chromium-review.googlesource.com/571530Reviewed-by: mark a. foltz <mfoltz@chromium.org>
Commit-Queue: Derek Cheng <imcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#486902}

chrome/test/media_router/media_router_integration_ui_browsertest.cc

@@ -46,9 +46,8 @@ IN_PROC_BROWSER_TEST_F(MediaRouterIntegrationBrowserTest, MANUAL_Dialog_Basic) {
   // closing after the route has been created. Then, check that the dialog
   // remains open.
   std::string mouse_enter_script = base::StringPrintf(
-      "domAutomationController.send("
-      "window.document.getElementById('media-router-container').dispatchEvent("
-      "new Event('mouseenter')))");
+      "window.document.getElementById('media-router-container')"
+      "    .dispatchEvent(new Event('mouseenter'));");
   ASSERT_TRUE(content::ExecuteScript(dialog_contents, mouse_enter_script));
 #endif
   WaitUntilRouteCreated();
@@ -121,9 +120,8 @@ IN_PROC_BROWSER_TEST_F(MediaRouterIntegrationBrowserTest, MANUAL_Dialog_Basic) {
   // the timer started when the route is initially closed times out before the
   // mouseleave event is dispatched. In that case, the dialog remains open.
   std::string mouse_leave_script = base::StringPrintf(
-      "domAutomationController.send("
-      "window.document.getElementById('media-router-container').dispatchEvent("
-      "new Event('mouseleave')))");
+      "window.document.getElementById('media-router-container')"
+      "    .dispatchEvent(new Event('mouseleave'));");
   ASSERT_TRUE(content::ExecuteScript(dialog_contents, mouse_leave_script));
 #endif
   LOG(INFO) << "Closing route on UI";