Sheriff: Disable a flaky test

Bug: 1064395
TBR: dominickn@chromium.org
Change-Id: If8bcce47c110603e49155f5476104a2d7f30e104
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2120835Reviewed-by: Hayato Ito <hayato@chromium.org>
Commit-Queue: Hayato Ito <hayato@chromium.org>
Cr-Commit-Position: refs/heads/master@{#753511}

chrome/android/javatests/src/org/chromium/chrome/browser/webapps/WebappModeTest.java

@@ -187,6 +187,7 @@ public class WebappModeTest {
     @Test
     @MediumTest
     @Feature({"Webapps"})
+    @DisabledTest(message = "crbug.com/1064395")
     public void testBringTabToFront() {
         // Start the WebappActivity.
         final WebappActivity firstActivity =