[Extensions] Re-enable a sync storage test that was disabled

for flakiness.

The UnlimitedStorageForLocalButNotSync was disabled long ago
for flakiness. This test passed 3000 iterations on the bots
with no flakes.

Bug: 227296
Change-Id: I24da0f1718658348dafb866c2eb6e7770400f843
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2196959Reviewed-by: Archana Simha <archanasimha@chromium.org>
Commit-Queue: David Bertoni <dbertoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#768544}

chrome/browser/extensions/api/storage/settings_sync_unittest.cc

@@ -1455,15 +1455,7 @@ static void UnlimitedLocalStorageTestCallback(ValueStore* local_storage) {
 
 }  // namespace
 
-#if defined(OS_WIN)
-// See: http://crbug.com/227296
-#define MAYBE_UnlimitedStorageForLocalButNotSync \
-  DISABLED_UnlimitedStorageForLocalButNotSync
-#else
-#define MAYBE_UnlimitedStorageForLocalButNotSync \
-  UnlimitedStorageForLocalButNotSync
-#endif
-TEST_F(ExtensionSettingsSyncTest, MAYBE_UnlimitedStorageForLocalButNotSync) {
+TEST_F(ExtensionSettingsSyncTest, UnlimitedStorageForLocalButNotSync) {
   const std::string id = "ext";
   std::set<std::string> permissions;
   permissions.insert("unlimitedStorage");