Revert "Disable flaky testAutoDismissPromo()"

This reverts commit 85afef48.

Reason for revert: Forgot to import DisabledTest

Original change's description:
> Disable flaky testAutoDismissPromo()
> 
> TBR=bsazonov@chromium.org,bauerb@chromium.org,iuliah@google.com
> 
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Bug: 789531
> Change-Id: I9ffa24762c4bd4f3b4d700acc827af8e5aca6eaf
> Reviewed-on: https://chromium-review.googlesource.com/796610
> Reviewed-by: Henrik Boström <hbos@chromium.org>
> Commit-Queue: Henrik Boström <hbos@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#520098}

TBR=bauerb@chromium.org,hbos@chromium.org,bsazonov@chromium.org,iuliah@google.com

Change-Id: I61722964a5ef5298d08cca37a6b188d0bc6a62c6
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 789531
Reviewed-on: https://chromium-review.googlesource.com/796893Reviewed-by: Henrik Boström <hbos@chromium.org>
Commit-Queue: Henrik Boström <hbos@chromium.org>
Cr-Commit-Position: refs/heads/master@{#520122}

chrome/android/javatests/src/org/chromium/chrome/browser/bookmarks/BookmarkPersonalizedSigninPromoTest.java

@@ -84,7 +84,6 @@ public class BookmarkPersonalizedSigninPromoTest {
     @Test
     @LargeTest
     @DisableIf.Device(type = {UiDisableIf.TABLET}) // https://crbug.com/776405.
-    @DisabledTest(message = "Flaky. See crbug.com/789531")
     public void testAutoDismissPromo() throws Exception {
         int impressionCap = SigninPromoController.getMaxImpressionsBookmarksForTests();
         for (int impression = 0; impression < impressionCap; impression++) {