sd-background.js

chrome.runtime.onInstalled.addListener((details) => {
  //console.log(details);
  if (details.reason.search(/install/g) === -1) {
      return
  }
  chrome.storage.local.set({keepLastOnly:true});
  chrome.tabs.create({
      url: chrome.extension.getURL("welcome.html"),
      active: true
  })
})

chrome.browserAction.onClicked.addListener(function(tab) {
  startScreenDrop(null);
});

let stream = null;
let mediaRecorder = null;
//let audioStream = null;
let audioTrack = null;


function downloadScreenDrop(url) {
  chrome.storage.local.get('keepLastOnly',(res) => {
    let filename = '';
    if (res.keepLastOnly)
      filename = 'screendrop.webm';
    else
      filename = 'screendrop-' + Date.now() + '.webm';
    chrome.downloads.download({
      url: url,
      filename: filename,
      conflictAction: res.keepLastOnly?'overwrite':'uniquify',
    }, (downloadId) => {
      //chrome.storage.local.set({downloadId});
    });
  });
}

async function startScreenDrop() {
  if (mediaRecorder) {
    stream.getTracks().forEach((t) => t.stop());
    mediaRecorder.stop();
    return;
  }
  try {
    let audioStream = await navigator.mediaDevices.getUserMedia({audio:true});
    audioTrack = audioStream.getAudioTracks()[0];
  } catch (eaudiopermission) {
    console.log('no audio',eaudiopermission);
  }

  try {
    stream = await navigator.mediaDevices.getDisplayMedia({/*video: true*//*, audio: true*/});
  } catch (epermission) {
    console.log('cancelled')
    return;
  }
  if (audioTrack)
    stream.addTrack(audioTrack);

  stream.getVideoTracks()[0].onended = function () {
    startScreenDrop();
  };
  let chunks = [];
  mediaRecorder = new MediaRecorder(stream,{mimeType:'video/webm;codecs=vp8,opus'});
  mediaRecorder.ondataavailable = (e) => {
    chunks.push(e.data);
  }
  mediaRecorder.onstop = function(e) {
    chrome.browserAction.setIcon({path: 'icons/off.png'});
    mediaRecorder = null;
    let blob = new Blob(chunks, { 'type' : 'video/webm' });
    chunks = [];
    let fr = new FileReader();
    fr.onload = (e) => {
      let url = fr.result;
      downloadScreenDrop(url);
    }
    fr.readAsDataURL(blob)
  };
  mediaRecorder.start(1000);
  /*chrome.storage.local.get(['downloadId','keep'],(res) => {
    if (res.downloadId) {
      if (!res.keep) {
        chrome.downloads.erase({id: res.downloadId});
        //chrome.downloads.removeFile(res.downloadId, () => {
        //  chrome.downloads.erase({id: res.downloadId});
        //});
      }
    }
  });*/
  chrome.browserAction.setIcon({path: 'icons/on.png'});
}