private void setSessionCreationRunnables(@Nullable Runnable onSuccess,
                @Nullable Runnable onFailure) {
            mOnSessionCreatedRunnable = onSuccess;
            mOnSessionCreationFailedRunnable = onFailure;
        }
Returns package name of the browser this TwaLauncher is launching.
customtabs/src/android/support/customtabs/trusted/TwaLauncher.java