[android] Add @RetryOnFailure to UrlOverridingTest.

Failing flakily on KitKat Tablet Tester.

TBR=hartmanng@chromium.org

Bug: 742430
Change-Id: Ideccbdb16ae9e5d8e9a25e44cbc07102b21076f1
Reviewed-on: https://chromium-review.googlesource.com/570186Reviewed-by: John Budorick <jbudorick@chromium.org>
Commit-Queue: John Budorick <jbudorick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#486564}

chrome/android/javatests/src/org/chromium/chrome/browser/externalnav/UrlOverridingTest.java

@@ -361,6 +361,7 @@ public class UrlOverridingTest {
     @Test
     @SmallTest
     @Restriction(ChromeRestriction.RESTRICTION_TYPE_TABLET)
+    @RetryOnFailure
     public void testOpenWindowFromUserGesture() throws InterruptedException {
         loadUrlAndWaitForIntentUrl(mTestServer.getURL(OPEN_WINDOW_FROM_USER_GESTURE_PAGE),
                 true, 1, true, null, true);