private String getRemoteVideoPixelSumScript() {
    return "function getSum(total, num) {"
      + "    return total + num;"
      + "};"
      + "var canvas = document.createElement('canvas');"
      + "var ctx = canvas.getContext('2d');"
      + "ctx.drawImage(remoteVideo,1,1,remoteVideo.videoHeight-1,remoteVideo.videoWidth-1);"
      + "var imageData = ctx.getImageData(1,1,remoteVideo.videoHeight-1,remoteVideo.videoWidth-1).data;"
      + "var sum = imageData.reduce(getSum);"
      + "if (sum===255*(Math.pow(remoteVideo.videoHeight-1,(remoteVideo.videoWidth-1)*(remoteVideo.videoWidth-1))))"
      + "   return 0;"
      + "return sum;";
  }
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