Re-enabled DefaultKeyboardExtensionBrowserTest.EndToEndTest.

The cause of the failure was fixed in crrev.com/c/645586.

Bug:515596
Test: Run the test 100 times on local machine

Change-Id: I64c613b23f3147f5c8cdb69f9c23adb1cb7bff21
Reviewed-on: https://chromium-review.googlesource.com/667556
Commit-Queue: Yuichiro Hanada <yhanada@chromium.org>
Reviewed-by: Toni Barzic <tbarzic@chromium.org>
Cr-Commit-Position: refs/heads/master@{#515454}

chrome/browser/chromeos/extensions/default_keyboard_extension_browser_test.cc

@@ -158,9 +158,7 @@ IN_PROC_BROWSER_TEST_F(DefaultKeyboardExtensionBrowserTest, IsKeyboardLoaded) {
   ASSERT_TRUE(loaded);
 }
 
-// Disabled; http://crbug.com/515596
-IN_PROC_BROWSER_TEST_F(DefaultKeyboardExtensionBrowserTest,
-                       DISABLED_EndToEndTest) {
+IN_PROC_BROWSER_TEST_F(DefaultKeyboardExtensionBrowserTest, EndToEndTest) {
   // Get the virtual keyboard's render view host.
   content::RenderViewHost* keyboard_rvh =
       GetKeyboardRenderViewHost(kExtensionId);