Merge pull request #10056 from davidflanagan/bug870327

Bug 870327: fix crash if sdcard is pulled while music is playing r=dkuo(cherry picked from commit e6b05b52f421c6122a31e9167cdeeb80d227d290)
Merge pull request #10138 from davidflanagan/bug870327-v1-train

Merge pull request #10056 from davidflanagan/bug870327