Validate the cache when the view asks whether it's up to date

It's a good opportunity to validate the cache when the view asks
whether there's more up to date data, otherwise views will never
get updated data if the cache is invalid already.

Author: shana

src/GitHub.Api/Cache/CacheContainer.cs

@@ -50,7 +50,8 @@ public IManagedCache GetCache(CacheType cacheType)
         public void CheckAndRaiseEventsIfCacheNewer(CacheUpdateEvent cacheUpdateEvent)
         {
             var cache = GetCache(cacheUpdateEvent.cacheType);
-            if (cache.LastUpdatedAt != cacheUpdateEvent.UpdatedTime)
+            var needsInvalidation = cache.ValidateData();
+            if (!needsInvalidation || cache.LastUpdatedAt != cacheUpdateEvent.UpdatedTime)
             {
                 OnCacheUpdated(cache.CacheType, cache.LastUpdatedAt);
             }