[sheriff] Disable TabFocusStealingFromMainFrame

The test is flaky.

TBR=lukasza@chromium.org

Bug: 1163630
Change-Id: I63691605c11a1ab5cc0adafaa03544d6fb6a974f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2637494Reviewed-by: Rainhard Findling <rainhard@chromium.org>
Commit-Queue: Rainhard Findling <rainhard@chromium.org>
Cr-Commit-Position: refs/heads/master@{#844713}

chrome/browser/extensions/omnibox_focus_interactive_test.cc

@@ -453,8 +453,9 @@ IN_PROC_BROWSER_TEST_F(OmniboxFocusInteractiveTest, TabFocusStealingFromOopif) {
 }
 
 // Tab focus should not be stolen by the omnibox - https://crbug.com/1127220.
+// TODO(crbug.com/1163630): Flaky test.
 IN_PROC_BROWSER_TEST_F(OmniboxFocusInteractiveTest,
-                       TabFocusStealingFromMainFrame) {
+                       DISABLED_TabFocusStealingFromMainFrame) {
   ASSERT_TRUE(embedded_test_server()->Start());
 
   // Open the new tab, focus should be on the location bar.