Android SurfaceViewRenderer: Fix eglBase null pointer exception

Add null checks for eglBase, and detach the egl context in
SurfaceViewRenderer.surfaceDestroyed().

BUG=webrtc:6032
R=sakal@webrtc.org

Review URL: https://codereview.webrtc.org/2124983002 .

Cr-Original-Commit-Position: refs/heads/master@{#13396}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 44abcb5e41c463f0b6f1c415a91052fe14058995
1 file changed