Address flaky test by waiting for focus change.

This change attempts to fix a flaky test by changing the KeyPress function to
use SendKeyPressAndWait which will wait for an event. The event that this test
will wait for is the focus change event that should get called when an element
in the web form changes focus.

BUG=405711

Review URL: https://codereview.chromium.org/503863002

Cr-Commit-Position: refs/heads/master@{#292220}

chrome/browser/ui/webui/options/language_options_interactive_uitest.cc

@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 #include "base/prefs/pref_service.h"
+#include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/ui/browser_window.h"
 #include "chrome/browser/ui/chrome_pages.h"
 #include "chrome/browser/ui/tabs/tab_strip_model.h"
@@ -60,14 +61,26 @@ class LanguageOptionsWebUITest : public InProcessBrowserTest {
     return GetActiveWebContents()->GetFocusedFrame();
   }
 
+  content::RenderViewHost* GetRenderViewHost() {
+    return GetActiveWebContents()->GetRenderViewHost();
+  }
+
   content::WebContents* GetActiveWebContents() {
     return browser()->tab_strip_model()->GetActiveWebContents();
   }
 
-  // Press and release a key in a particular window. Returns false on error.
+  // Press and release a key in the browser. This will wait for the element on
+  // the page to change.
   bool PressKey(ui::KeyboardCode key_code) {
-    return ui_test_utils::SendKeyPressSync(browser(), key_code,
-                                           false, false, false, false);
+    return ui_test_utils::SendKeyPressAndWait(
+        browser(),
+        key_code,
+        false,
+        false,
+        false,
+        false,
+        content::NOTIFICATION_FOCUS_CHANGED_IN_PAGE,
+        content::Source<content::RenderViewHost>(GetRenderViewHost()));
   }
 
  private:
@@ -116,8 +129,7 @@ IN_PROC_BROWSER_TEST_F(LanguageOptionsWebUITest, TestAvailableLanguages) {
 // This test must be updated if the tab order of the elements on this page
 // is chagned.
 // flaky: http://crbug.com/405711
-IN_PROC_BROWSER_TEST_F(LanguageOptionsWebUITest,
-                       DISABLED_TestListTabAccessibility) {
+IN_PROC_BROWSER_TEST_F(LanguageOptionsWebUITest, TestListTabAccessibility) {
   // Verify that the language list is focused by default.
   std::string original_id = GetActiveElementId();
   EXPECT_EQ("language-options-list", original_id);