mac: Reenable message_center_unittests MessagePopupCollectionTest.UpdateContentsCausesPopupClose

This was only failing on 10.10 and Chromium no longer supports that
version of macOS.

Bug: 1047503, 1153883
Change-Id: Icf30557034eb5bcc5bde2a40763901e2d56104a6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2574621
Commit-Queue: Justin DeWitt <dewittj@chromium.org>
Reviewed-by: Justin DeWitt <dewittj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#834418}

ui/message_center/views/message_popup_collection_unittest.cc

@@ -437,14 +437,7 @@ TEST_F(MessagePopupCollectionTest, UpdateContents) {
   EXPECT_TRUE(GetPopup(id)->updated());
 }
 
-// Failiing on MacOS 10.10. https://crbug.com/1047503
-#if defined(OS_APPLE)
-#define MAYBE_UpdateContentsCausesPopupClose \
-  DISABLED_UpdateContentsCausesPopupClose
-#else
-#define MAYBE_UpdateContentsCausesPopupClose UpdateContentsCausesPopupClose
-#endif
-TEST_F(MessagePopupCollectionTest, MAYBE_UpdateContentsCausesPopupClose) {
+TEST_F(MessagePopupCollectionTest, UpdateContentsCausesPopupClose) {
   std::string id = AddNotification();
   AnimateToEnd();
   RunPendingMessages();