6d5176638c
Implement a more consistent policy for system and UI sounds (key clicks, lock/unlock, camera shutter, DTMF, low battery...): - All system sounds are played over STREAM_SYSTEM stream type. - The STREAM_SYSTEM volume that was previously fixed now tracks the volume of a "master" stream type. This "master" stream type is STREAM_RING for phones and STREAM_MUSIC for tablets which corresponds to the stream whose volume is modified by default by the volume keys. - The STREAM_SYSTEM volume ranges from -24dB to -6dB (-24dB to -12dB over headphones) when the "master" stream volume ranges from its min to its max. - DTMF tones are played over STREAM_DTMF that tracks the "master" stream volume in the same manner with the following exception: when in call, DTMF stream tracks STREAM_VOICE_CALL volume. - Camera shutter sound is played over STREAM_SYSTEM_ENFORCED stream that tracks the "master" stream volume except in countries where regulation enforces this sound. In this case its volume is fixed and cannot be muted. - Low battery sound is played over STREAM_SYSTEM and therefore has a tunable volume and is heard while in call. Issue 6344620. Issue 6069229. Issue 6213100. Change-Id: I53a237878ead596e706c5dbbb1420e62cde32bd7