Bug 5249076 When starting to stream, have at least one buffer in shared mem

Bug 5249076 When starting to stream, have at least one buffer in shared mem

StreamPlayer is receiving notifications from the MediaPlayer that
 a buffer in shared memory is available during playback, which
 causes StreamPlayer to consume data from the AndroidBufferQueue.
 If the shared memory is drained while the player is paused, there
 will be no new notification of a buffer in shared memory being
 available to start the cycle of consumption from the Android
 buffer queue.
This change causes StreamPlayer to consume from the buffer queue
 to fill one buffer in shared memory.
A subsequent change will change the logic to make sure the
 consumption from the buffer queue fills as much of the shared
 memory as possible.

Change-Id: I886832629dd5ef449719b77899ebdcc7ffc64330