stagefright: offload playback support

Offloading of compressed audio decoding to audio DSP
is implemented for audio only, non streamed content.
when the datasource is

AudioPlayer:
- Create an offloaded sink when playing a compressed
source
- Send metadata to audio HAL
- Return sink start error to AwesomePlayer so that a
new player for PCM audio can be created in case of problem.
- Forward stream end and tear down callback events to AwesomePlayer
- Stop the sink and wait for stream end callback when EOS is reached.
- Pause and restart the sink if needed before flushing when seeking
(otherwise flush is a no op).
- For current media time, directly query the render position from the
sink and offset by the start position (seek to time)

AwesomePlayer:

- When initializing the audio decoder, check with audio policy manager
if offloading is supported. If yes, create the software decoder in
case a reconfiguration is needed but connect the audio track directly
to the AudioPlayer.
- In case of error when starting the AudioPlayer, reconnect the software
decoder (OMXSource) and recreate a PCM AudioPlayer.
- Handle AudioPlayer tear down event by detroying and recreating the
AudioPlayer to allow transitions between situations were offloading
is supported or not.
- Force tear down of offloaded AudioPlayer when paused for a certain time:
This will close the sink and allow the DSP to power down.

Utils:
- Added helper methods:
    - send meta data to audio ia sink setParameters
    - query audio policy manager if offloading is supported for a
given audio content

Change-Id: I115842ce424f947b966d45e253a74d3fd5df9aae
Signed-off-by: Eric Laurent <elaurent@google.com>
8 files changed