Add VPX output buffer size check

and handle dead observers more gracefully

Bug: 27597103
Change-Id: Id7acb25d5ef69b197da15ec200a9e4f9e7b03518

status_t OMX::prepareForAdaptivePlayback(
        node_id node, OMX_U32 portIndex, OMX_BOOL enable,
        OMX_U32 maxFrameWidth, OMX_U32 maxFrameHeight) {
 return findInstance(node)->prepareForAdaptivePlayback(
            portIndex, enable, maxFrameWidth, maxFrameHeight);
}

status_t OMX::prepareForAdaptivePlayback(
        node_id node, OMX_U32 portIndex, OMX_BOOL enable,
        OMX_U32 maxFrameWidth, OMX_U32 maxFrameHeight) {
 return findInstance(node)->prepareForAdaptivePlayback(
            portIndex, enable, maxFrameWidth, maxFrameHeight);
}
