Kemosabe/RCA's R.City and Adam Levine will stay on top of the Pop chart for another week with "Locked Away," but don't you dare blink because The Weeknd's unstoppable power ballad "The Hills" (XO/Republic) is coming up very quickly behind it. Meanwhile, the chart's Greatest Gainer this week, Justin Bieber's "What Do You Mean?" (Def Jam), is quickly shaping up to pose its own takeover.  In the coming weeks we'll have three giant records vying for that coveted #1 position—  don't forget Taylor Swift is gunning for her fifth #1 with "Wildest Dreams" (Big Machine/Republic).   Island/Republic's Shawn Mendes takes a leap halfway up the Top 10 with "Stitches," moving from #10 to #5.  Joining the Top 10 will be One Direction's "Drag Me Down" (SYCO/Columbia). There are three tracks charting this week: Demi Lovato's "Confident" ( Island/Hollywood-Republic), DNCE's "Cake By The Ocean" (Republic) and Nico & Vinz f/B.Rexha's "That's How You Know" (Warner Bros).