aw: Enable AwSettingsTest.testDatabaseEnabled

I did about 800 run on Nexus 5x on Android N and 200 run on Pixel on
Android master, all of them passed, so try to reenable it.

Bug: 767180
Change-Id: Ie373a37271aabb5008ac700ff29779f134e5faea
Reviewed-on: https://chromium-review.googlesource.com/776206Reviewed-by: Bo <boliu@chromium.org>
Commit-Queue: Shimi Zhang <ctzsm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#517504}

android_webview/javatests/src/org/chromium/android_webview/test/AwSettingsTest.java

@@ -1826,12 +1826,10 @@ public class AwSettingsTest {
         helper.ensureSettingHasInitialValue();
     }
 
-    /*
-     * @SmallTest
-     * @Feature({"AndroidWebView", "Preferences"})
-     */
     @Test
-    @DisabledTest(message = "crbug.com/767180")
+    @SmallTest
+    @Feature({"AndroidWebView", "Preferences"})
+    @RetryOnFailure
     public void testDatabaseEnabled() throws Throwable {
         TestAwContentsClient client = new TestAwContentsClient();
         final AwTestContainerView testContainerView =