Revert "Disable flaky test testFileDeletedIfStoreWebApkUpdateRequestToFileFails"

This reverts commit 6c5b9879.

Reason for revert: <INSERT REASONING HERE>

Original change's description:
> Disable flaky test testFileDeletedIfStoreWebApkUpdateRequestToFileFails
> 
> TBR=pkotwicz@chromium.org
> NOTRY=true
> 
> Bug: 937242
> Change-Id: Ic705e4dcfa5abb1dcd0ff5baa32b51f7f84c6b42
> Reviewed-on: https://chromium-review.googlesource.com/c/1496765
> Reviewed-by: Yi Gu <yigu@chromium.org>
> Commit-Queue: Yi Gu <yigu@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#636805}

TBR=pkotwicz@chromium.org,yigu@chromium.org

Change-Id: Ib48da2f508e3fd302c5116ca23e2b9fd0030b727
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 937242
Reviewed-on: https://chromium-review.googlesource.com/c/1495970Reviewed-by: Yi Gu <yigu@chromium.org>
Commit-Queue: Yi Gu <yigu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#636814}

chrome/android/junit/src/org/chromium/chrome/browser/webapps/WebApkUpdateManagerUnitTest.java

@@ -32,7 +32,6 @@ import org.chromium.base.CommandLine;
 import org.chromium.base.PathUtils;
 import org.chromium.base.task.test.CustomShadowAsyncTask;
 import org.chromium.base.test.BaseRobolectricTestRunner;
-import org.chromium.base.test.util.DisabledTest;
 import org.chromium.base.test.util.JniMocker;
 import org.chromium.blink_public.platform.WebDisplayMode;
 import org.chromium.chrome.browser.ShortcutHelper;
@@ -555,9 +554,7 @@ public class WebApkUpdateManagerUnitTest {
      * {@link WebApkUpdateManager#nativeStoreWebApkUpdateRequestToFile} creates the pending update
      * file but fails.
      */
-    // @Test
-    // This test is flaky. See https://crbug.com/937242.
-    @DisabledTest
+    @Test
     public void testFileDeletedIfStoreWebApkUpdateRequestToFileFails() {
         mClockRule.advance(WebappDataStorage.UPDATE_INTERVAL);