private String getStashedResolutionScript() {
    return "return JSON.stringify(window.resolution);";
  }
Returns the test's canvasCheck to check if the video is blank, and if it changes overtime.

@return the getRemoteVideoPixelSumScript as string.
KITE-AppRTC-Test/src/main/java/org/webrtc/kite/apprtc/pages/AppRTCMeetingPage.java