Unhide AudioManager method to query whether a given
format can be offloaded on the device.
Unhide AudioTrack.Builder method to request offload.
Unhide callback for new AudioTrack events and
associated methods.
Implement registration and callback for stream events.
JNI: configure native AudioTrack for offload.
Remove unused imports.
Bug 113352077
Bug 86837964
Test: "make offline-sdk-docs" and "adb shell clof --source /sdcard/Music/my.mp3"
Change-Id: I565668913076a57ea2c444f1f9268b21024ccde0
03f51393d8