MM-10272: Add a count for pinned posts header icon (#11840)

app/channel.go

@@ -1330,6 +1330,10 @@ func (a *App) GetChannelGuestCount(channelId string) (int64, *model.AppError) {
 	return a.Srv.Store.Channel().GetGuestCount(channelId, true)
 }
 
+func (a *App) GetChannelPinnedPostCount(channelId string) (int64, *model.AppError) {
+	return a.Srv.Store.Channel().GetPinnedPostCount(channelId, true)
+}
+
 func (a *App) GetChannelCounts(teamId string, userId string) (*model.ChannelCounts, *model.AppError) {
 	return a.Srv.Store.Channel().GetChannelCounts(teamId, userId)
 }

app/web_hub.go

@@ -289,6 +289,7 @@ func (a *App) InvalidateCacheForChannelPosts(channelId string) {
 
 func (a *App) InvalidateCacheForChannelPostsSkipClusterSend(channelId string) {
 	a.Srv.Store.Post().InvalidateLastPostTimeCache(channelId)
+	a.Srv.Store.Channel().InvalidatePinnedPostCount(channelId)
 }
 
 func (a *App) InvalidateCacheForUser(userId string) {