Bug 1314530 Part1 - Remove IsInPrivateBrowsing() since we did not use it anymore. r=cpearce

MozReview-Commit-ID: J8tfOyzBB97

--HG--
extra : rebase_source : fc667dcb1eb47d44f94da4d65160cde6dba8a2d9

dom/media/eme/MediaKeys.h

@@ -133,8 +133,6 @@ public:
 
 private:
 
-  bool IsInPrivateBrowsing();
-
   // Removes promise from mPromises, and returns it.
   already_AddRefed<DetailedPromise> RetrievePromise(PromiseId aId);