public void unbindCustomTabsService(Activity activity) {
        if (mConnection == null) return;
        activity.unbindService(mConnection);
        mClient = null;
        mCustomTabsSession = null;
        mConnection = null;
    }
Unbinds the Activity from the Custom Tabs Service.
@param activity the activity that is connected to the service.
demos/src/main/java/org/chromium/customtabsdemos/CustomTabActivityHelper.java