Disable flaky AdRedirectTriggerBrowserTest.

TBR=vakh@chromium.org

Bug: 978405
Change-Id: Ie54327a833a55add5ee6882ce2ae2d93eb0a8ec3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1675670Reviewed-by: Rune Lillesveen <futhark@chromium.org>
Commit-Queue: Rune Lillesveen <futhark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#672045}

chrome/browser/safe_browsing/ad_redirect_trigger_browsertest.cc

@@ -104,8 +104,9 @@ class AdRedirectTriggerBrowserTest : public InProcessBrowserTest,
 };
 
 // Check that a report is sent when the source of a blocked redirect is an ad.
+// TODO(https://crbug.com/978405) Disabled due to flakiness.
 IN_PROC_BROWSER_TEST_F(AdRedirectTriggerBrowserTest,
-                       BlockRedirectNavigation_FromAd) {
+                       DISABLED_BlockRedirectNavigation_FromAd) {
   base::HistogramTester histogram_tester;
   CreateTrigger();
   ui_test_utils::NavigateToURL(browser(),