Revert of exclude failing test...

Revert of exclude failing test BrowserOptionsOverlayWebUITest.testNavigationInBackground on drmemory bot (patchset #1 of https://codereview.chromium.org/470813002/)

Reason for revert:
Test has been patched.

Original issue's description:
> exclude failing test BrowserOptionsOverlayWebUITest.testNavigationInBackground on drmemory bot
>
> BUG=403627
> TBR=michaelpg@chromium.org
>
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=289441

BUG=403627

Review URL: https://codereview.chromium.org/495803002

Cr-Commit-Position: refs/heads/master@{#297260}

tools/valgrind/gtest_exclude/browser_tests.gtest-drmemory.txt

@@ -4,9 +4,6 @@ InterstitialUITest.OpenInterstitial
 # http://crbug.com/400509
 CustomLauncherPageBrowserTest.LoadPageAndOpenLauncher
 
-# http://crbug.com/403627
-BrowserOptionsOverlayWebUITest.testNavigationInBackground
-
 # http://crbug.com/403628
 RangeHistoryWebUITest.monthViewGrouped