SDK / exoplayer

Without this developers which reuse a SurfaceHolder with multiple instances of
SimpleExoPlayer need to call simpleExoPlayer.setVideoSurfaceHolder(null) to get
the SimpleExoPlayer.ComponentListener removed from the surface holder. If they
don't, the component listener is still registered and as a member class leaks
an instance of simpleExoPlayer.

Issue #1855

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=135292439