bug:9621717
Because we're no longer holding onto Bitmaps Java side during
DisplayList lifetime, use global refs to keep the backing byte arrays
around.
Adds back bitmap buffer passing + native ref management removed by
3b748a44c6bd2ea05fe16839caf73dbe50bd7ae9
Adds back globalRef-ing removed by
f890fab5a6715548e520a6f010a3bfe7607ce56e
Change-Id: Ia59ba42f05bea6165aec2b800619221a8083d580