Merge "Fix clean-up order when player crashes" into main

        if (mTransitionPlayer == null) return;

        // Immediately set to null so that nothing inadvertently starts/queues.

        mTransitionPlayer = null;

        // Clean-up/finish any playing transitions.

        for (int i = 0; i < mPlayingTransitions.size(); ++i) {

        // Clean-up/finish any playing transitions. Backwards since they can remove themselves.

        for (int i = mPlayingTransitions.size() - 1; i >= 0; --i) {

            mPlayingTransitions.get(i).cleanUpOnFailure();

        }

        mPlayingTransitions.clear();

        // Clean up waiting transitions first since they technically started first.

        for (int i = 0; i < mWaitingTransitions.size(); ++i) {

        // Backwards since they can remove themselves.

        for (int i = mWaitingTransitions.size() - 1; i >= 0; --i) {

            mWaitingTransitions.get(i).abort();

        }

        mWaitingTransitions.clear();