gistfile1.txt

// The below is pseudocode.

// mapperTab.js is the output of the build process from
// https://github.com/GoogleChromeLabs/chromium-bidi
string bidiMapperTabContent = getFileContent("/path/to/mapperTab.js");

// WebSocket address is found by monitoring console output of
// executing Chrome, and parsing the "DevTools listening on ws://xxx"
string webSocketUrl = launchChrome();

// Connect to the WebSocket (assume this all does the right thing
// to handle the duplex communication).
WebSocketConnection connection = new(webSocketUrl);

object response = connection.send(JSON.stringify({
  id: 0,
  method: "Target.getTargets",
  params: {}
});
string targetId = response["result"]["targetInfos"][0]["targetId"];

response = connection.send(JSON.stringify({
  id: 1,
  method: "Target.attachToTarget",
  params: {
    targetId: targetId,
    flatten: true
  }
});
string sessionId = response["result"]["sessionId"]

response = connection.send(JSON.stringify({
  id: 2,
  method: "Target.exposeDevToolsProtocol",
  params: {
    bindingName: "cdp",
    targetId: targetId
  }
});

response = connection.send(JSON.stringify({
  id: 3,
  method: "Runtime.addBinding",
  params: {
    name: "sendBidiResponse"
  },
  sessionId: sessionId
});

// To prevent the beforeunload prompt from appearing on close
response = connection.send(JSON.stringify({
  id: 4,
  method: "Runtime.evaluate",
  params: {
    expression: "document.body.click()",
    userGesture: true
  }
});

response = connection.send(JSON.stringify({
  id: 5,
  method: "Runtime.evaluate",
  params: {
    expression: `"${bidiMapperTabContent}"`,
  },
  sessionId: sessionId
});

response = connection.send(JSON.stringify({
  id: 6,
  method: "Runtime.evaluate",
  params: {
    expression: `"window.runMapperInstance(${targetId}, {})"`,
    awaitPromise: true
  },
  sessionId: sessionId
});