Merge pull request #14887 from ian-liu/bluetooth/bug951566_fix_unknown_filename_while_sharing_blobs_without_name

Bug 951566 - [Bluetooth][Bluedroid] Unknown.jpeg shown in notification after file transfer via Bluetooth, r=@dominickuo
(cherry picked from commit 503af44c30a96eb0db5eab0ee6bfbeb397dea9bf)