After https://codereview.webrtc.org/1827263002, audio devices are no
longer (ever) initialized if they return true from
RecordingIsInitialized. Since this was left as "return true;" for
file_audio_device, the recording buffer was never set up correctly, and
the audio buffer would assert when called (in debug) and FileAudioDevice
would cause memory corruption (in release).
BUG=
Review-Url: https://codereview.webrtc.org/2116003003
Cr-Commit-Position: refs/heads/master@{#13489}
28fdf5637f