3 files changed, 1445 insertions, 0 deletions
diff --git a/toolkit/content/aboutwebrtc/aboutWebrtc.css b/toolkit/content/aboutwebrtc/aboutWebrtc.css
new file mode 100644
index 0000000000..a1270b41a6
--- /dev/null
+++ b/toolkit/content/aboutwebrtc/aboutWebrtc.css
@@ -0,0 +1,173 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+body {
+  margin: 8px;
+}
+
+table {
+  font-family: monospace;
+  border: 1px solid var(--in-content-border-color);
+  border-spacing: 0;
+  margin-block: 1em;
+}
+
+.controls {
+  font-size: 1.1em;
+  display: inline-block;
+  margin: 0 0.5em;
+}
+
+.control {
+  margin: 0.5em 0;
+}
+
+.message > p {
+  margin: 4px;
+}
+
+.log p,
+.prefs p {
+  font-family: monospace;
+  padding-inline-start: 2em;
+  text-indent: -2em;
+  margin-block: 2px;
+}
+
+#content > div {
+  padding: 1em 2em;
+  margin: 1em 0;
+  border: 1px solid var(--in-content-box-border-color);
+  border-radius: 10px;
+  background-color: var(--in-content-box-background);
+}
+
+.section-heading > * {
+  display: inline-block;
+}
+
+.section-heading > button {
+  margin-inline: 1em;
+}
+
+.peer-connection > h3 {
+  background-color: var(--in-content-box-info-background);
+  padding: 4px;
+}
+
+.peer-connection > button {
+  margin-inline-start: 0;
+}
+
+.peer-connection table {
+  width: 100%;
+  text-align: center;
+}
+
+.peer-connection table th {
+  font-weight: bold;
+}
+
+.peer-connection table th,
+.peer-connection table td {
+  padding: 0.4em;
+  border: 1px solid var(--in-content-border-color);
+}
+
+.peer-connection table tr:nth-child(odd) {
+  background-color: var(--in-content-box-background-odd);
+}
+
+.peer-connection table caption {
+  text-align: start;
+}
+
+.peer-connection table.raw-candidate {
+  text-align: match-parent;
+}
+
+.bottom-border td {
+  border-bottom: 2px solid currentColor;
+}
+
+.peer-connection-config div {
+  margin-inline: 1em;
+  padding: 4px;
+  border: 1px solid var(--in-content-border-color);
+}
+
+.peer-connection-config div:nth-child(odd) {
+  background-color: var(--in-content-box-background-odd);
+}
+
+/* The pale colour scheme is taken from:
+   https://personal.sron.nl/~pault/#sec:qualitative */
+.ice-trickled {
+  background-color: #cceeff; /* pale cyan */
+}
+.ice-succeeded {
+  background-color: #ccddaa; /* pale green */
+}
+.ice-failed {
+  background-color: #ffcccc; /* pale red */
+}
+.ice-cancelled {
+  background-color: #eeeebb; /* pale yellow */
+}
+.ice-trickled,
+.ice-succeeded,
+.ice-failed,
+.ice-cancelled {
+  color: black
+}
+
+.info-label {
+  font-weight: bold;
+}
+
+.info-body,
+.stat-label {
+  padding-inline-start: 0.5em;
+}
+
+.section-ctrl {
+  margin: 1em 1.5em;
+}
+
+div.fold-trigger {
+  color: var(--blue-60);
+  cursor: pointer;
+}
+
+@media screen {
+  .fold-closed {
+    display: none !important;
+  }
+}
+
+@media print {
+  .no-print {
+    display: none !important;
+  }
+}
+
+.sdp-history {
+  display: flex;
+  height: 400px;
+}
+
+.sdp-history-link {
+  text-decoration: underline;
+}
+
+.sdp-history h5 {
+  background-color: var(--in-content-box-info-background);
+}
+
+.sdp-history div {
+  border: 1px solid var(--in-content-border-color);
+  padding: 1em;
+  width: 50%;
+  overflow: scroll;
+}
diff --git a/toolkit/content/aboutwebrtc/aboutWebrtc.html b/toolkit/content/aboutwebrtc/aboutWebrtc.html
new file mode 100644
index 0000000000..14ffab8c5f
--- /dev/null
+++ b/toolkit/content/aboutwebrtc/aboutWebrtc.html
@@ -0,0 +1,24 @@
+<!DOCTYPE HTML>
+
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<html>
+<head>
+  <meta http-equiv="Content-Security-Policy" content="default-src chrome:; object-src 'none'" />
+  <meta charset="utf-8" />
+  <meta name="color-scheme" content="light dark">
+  <title data-l10n-id="about-webrtc-document-title"></title>
+  <link rel="stylesheet" href="chrome://global/skin/in-content/common.css">
+  <link rel="stylesheet" type="text/css" media="all"
+    href="chrome://global/content/aboutwebrtc/aboutWebrtc.css"/>
+  <script src="chrome://global/content/aboutwebrtc/aboutWebrtc.js"
+          defer="defer"></script>
+  <link rel="localization" href="toolkit/about/aboutWebrtc.ftl"/>
+</head>
+<body id="body">
+  <div id="controls" class="no-print"></div>
+  <div id="content"></div>
+</body>
+</html>
diff --git a/toolkit/content/aboutwebrtc/aboutWebrtc.js b/toolkit/content/aboutwebrtc/aboutWebrtc.js
new file mode 100644
index 0000000000..707cf537d5
--- /dev/null
+++ b/toolkit/content/aboutwebrtc/aboutWebrtc.js
@@ -0,0 +1,1248 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+"use strict";
+
+const { XPCOMUtils } = ChromeUtils.importESModule(
+  "resource://gre/modules/XPCOMUtils.sys.mjs"
+);
+
+ChromeUtils.defineESModuleGetters(this, {
+  FileUtils: "resource://gre/modules/FileUtils.sys.mjs",
+});
+XPCOMUtils.defineLazyServiceGetter(
+  this,
+  "FilePicker",
+  "@mozilla.org/filepicker;1",
+  "nsIFilePicker"
+);
+
+const WGI = WebrtcGlobalInformation;
+
+const LOGFILE_NAME_DEFAULT = "aboutWebrtc.html";
+const WEBRTC_TRACE_ALL = 65535;
+
+async function getStats() {
+  const { reports } = await new Promise(r => WGI.getAllStats(r));
+  return [...reports].sort((a, b) => b.timestamp - a.timestamp);
+}
+
+const getLog = () => new Promise(r => WGI.getLogging("", r));
+
+const renderElement = (name, options, l10n_id, l10n_args) => {
+  let elem = Object.assign(document.createElement(name), options);
+  if (l10n_id) {
+    document.l10n.setAttributes(elem, l10n_id, l10n_args);
+  }
+  return elem;
+};
+
+const renderText = (name, textContent, options) =>
+  renderElement(name, Object.assign({ textContent }, options));
+
+const renderElements = (name, options, list) => {
+  const element = renderElement(name, options);
+  element.append(...list);
+  return element;
+};
+
+// Button control classes
+
+class Control {
+  label = null;
+  message = null;
+  messageArgs = null;
+  messageHeader = null;
+
+  render() {
+    this.ctrl = renderElement(
+      "button",
+      { onclick: () => this.onClick() },
+      this.label
+    );
+    this.msg = renderElement("p");
+    this.update();
+    return [this.ctrl, this.msg];
+  }
+
+  update() {
+    document.l10n.setAttributes(this.ctrl, this.label);
+    this.msg.textContent = "";
+    if (this.message) {
+      this.msg.append(
+        renderElement(
+          "span",
+          {
+            className: "info-label",
+          },
+          this.messageHeader
+        ),
+        renderElement(
+          "span",
+          {
+            className: "info-body",
+          },
+          this.message,
+          this.messageArgs
+        )
+      );
+    }
+  }
+}
+
+class SavePage extends Control {
+  constructor() {
+    super();
+    this.messageHeader = "about-webrtc-save-page-label";
+    this.label = "about-webrtc-save-page-label";
+  }
+
+  async onClick() {
+    FoldEffect.expandAll();
+    let [dialogTitle] = await document.l10n.formatValues([
+      { id: "about-webrtc-save-page-dialog-title" },
+    ]);
+    FilePicker.init(window, dialogTitle, FilePicker.modeSave);
+    FilePicker.defaultString = LOGFILE_NAME_DEFAULT;
+    const rv = await new Promise(r => FilePicker.open(r));
+    if (rv != FilePicker.returnOK && rv != FilePicker.returnReplace) {
+      return;
+    }
+    const fout = FileUtils.openAtomicFileOutputStream(
+      FilePicker.file,
+      FileUtils.MODE_WRONLY | FileUtils.MODE_CREATE
+    );
+    const content = document.querySelector("#content");
+    const noPrintList = [...content.querySelectorAll(".no-print")];
+    for (const node of noPrintList) {
+      node.style.setProperty("display", "none");
+    }
+    try {
+      fout.write(content.outerHTML, content.outerHTML.length);
+    } finally {
+      FileUtils.closeAtomicFileOutputStream(fout);
+      for (const node of noPrintList) {
+        node.style.removeProperty("display");
+      }
+    }
+    this.message = "about-webrtc-save-page-msg";
+    this.messageArgs = { path: FilePicker.file.path };
+    this.update();
+  }
+}
+
+class DebugMode extends Control {
+  constructor() {
+    super();
+    this.messageHeader = "about-webrtc-debug-mode-msg-label";
+
+    if (WGI.debugLevel > 0) {
+      this.setState(true);
+    } else {
+      this.label = "about-webrtc-debug-mode-off-state-label";
+    }
+  }
+
+  setState(state) {
+    this.label = state
+      ? "about-webrtc-debug-mode-on-state-label"
+      : "about-webrtc-debug-mode-off-state-label";
+    try {
+      const file = Services.prefs.getCharPref("media.webrtc.debug.log_file");
+      this.message = state
+        ? "about-webrtc-debug-mode-on-state-msg"
+        : "about-webrtc-debug-mode-off-state-msg";
+      this.messageArgs = { path: file };
+    } catch (e) {
+      this.message = null;
+    }
+    return state;
+  }
+
+  onClick() {
+    this.setState((WGI.debugLevel = WGI.debugLevel ? 0 : WEBRTC_TRACE_ALL));
+    this.update();
+  }
+}
+
+class AecLogging extends Control {
+  constructor() {
+    super();
+    this.messageHeader = "about-webrtc-aec-logging-msg-label";
+
+    if (WGI.aecDebug) {
+      this.setState(true);
+    } else {
+      this.label = "about-webrtc-aec-logging-off-state-label";
+      this.message = null;
+    }
+  }
+
+  setState(state) {
+    this.label = state
+      ? "about-webrtc-aec-logging-on-state-label"
+      : "about-webrtc-aec-logging-off-state-label";
+    try {
+      if (!state) {
+        const file = WGI.aecDebugLogDir;
+        this.message = "about-webrtc-aec-logging-off-state-msg";
+        this.messageArgs = { path: file };
+      } else {
+        this.message = "about-webrtc-aec-logging-on-state-msg";
+      }
+    } catch (e) {
+      this.message = null;
+    }
+  }
+
+  onClick() {
+    this.setState((WGI.aecDebug = !WGI.aecDebug));
+    this.update();
+  }
+}
+
+class ShowTab extends Control {
+  constructor(browserId) {
+    super();
+    this.label = "about-webrtc-show-tab-label";
+    this.message = null;
+    this.browserId = browserId;
+  }
+
+  onClick() {
+    const gBrowser =
+      window.ownerGlobal.browsingContext.topChromeWindow.gBrowser;
+    for (const tab of gBrowser.visibleTabs) {
+      if (tab.linkedBrowser && tab.linkedBrowser.browserId == this.browserId) {
+        gBrowser.selectedTab = tab;
+        return;
+      }
+    }
+    this.ctrl.disabled = true;
+  }
+}
+
+(async () => {
+  // Setup. Retrieve reports & log while page loads.
+  const haveReports = getStats();
+  const haveLog = getLog();
+  await new Promise(r => (window.onload = r));
+  {
+    const ctrl = renderElement("div", { className: "control" });
+    const msg = renderElement("div", { className: "message" });
+    const add = ([control, message]) => {
+      ctrl.appendChild(control);
+      msg.appendChild(message);
+    };
+    add(new SavePage().render());
+    add(new DebugMode().render());
+    add(new AecLogging().render());
+    // Add the autorefresh checkbox and its label
+    const autorefresh = document.createElement("input");
+    Object.assign(autorefresh, {
+      type: "checkbox",
+      id: "autorefresh",
+      checked: true,
+    });
+    const autorefreshLabel = document.createElement("label");
+    document.l10n.setAttributes(
+      autorefreshLabel,
+      "about-webrtc-auto-refresh-label"
+    );
+
+    const ctrls = document.querySelector("#controls");
+    ctrls.append(renderElements("div", { className: "controls" }, [ctrl, msg]));
+    ctrls.appendChild(autorefresh);
+    ctrls.appendChild(autorefreshLabel);
+  }
+
+  // Render pcs and log
+  let reports = await haveReports;
+  let log = await haveLog;
+
+  reports.sort((a, b) => a.browserId - b.browserId);
+
+  let peerConnections = renderElement("div");
+  let connectionLog = renderElement("div");
+  let userPrefs = renderElement("div");
+
+  const content = document.querySelector("#content");
+  content.append(peerConnections, connectionLog, userPrefs);
+
+  // This does not handle the auto-refresh, only the manual refreshes needed
+  // for certain user actions, and the initial population of the data
+  function refresh() {
+    const pcDiv = renderElements("div", { className: "stats" }, [
+      renderElements("span", { className: "section-heading" }, [
+        renderElement("h3", {}, "about-webrtc-stats-heading"),
+        renderElement(
+          "button",
+          {
+            className: "no-print",
+            onclick: async () => {
+              WGI.clearAllStats();
+              reports = await getStats();
+              refresh();
+            },
+          },
+          "about-webrtc-stats-clear"
+        ),
+      ]),
+      ...reports.map(renderPeerConnection),
+    ]);
+    const logDiv = renderElements("div", { className: "log" }, [
+      renderElements("span", { className: "section-heading" }, [
+        renderElement("h3", {}, "about-webrtc-log-heading"),
+        renderElement(
+          "button",
+          {
+            className: "no-print",
+            onclick: async () => {
+              WGI.clearLogging();
+              log = await getLog();
+              refresh();
+            },
+          },
+          "about-webrtc-log-clear"
+        ),
+      ]),
+    ]);
+    if (log.length) {
+      const div = renderFoldableSection(logDiv, {
+        showMsg: "about-webrtc-log-show-msg",
+        hideMsg: "about-webrtc-log-hide-msg",
+      });
+      div.append(...log.map(line => renderText("p", line)));
+      logDiv.append(div);
+    }
+    // Replace previous info
+    peerConnections.replaceWith(pcDiv);
+    connectionLog.replaceWith(logDiv);
+    userPrefs.replaceWith((userPrefs = renderUserPrefs()));
+
+    peerConnections = pcDiv;
+    connectionLog = logDiv;
+  }
+  refresh();
+
+  async function translate(element) {
+    const frag = document.createDocumentFragment();
+    frag.append(element);
+    await document.l10n.translateFragment(frag);
+    return frag;
+  }
+
+  window.setInterval(
+    async history => {
+      // Only refresh if the autorefresh checkbox is checked
+      if (!document.getElementById("autorefresh").checked) {
+        return;
+      }
+      const reports = await getStats();
+
+      const translateSection = async (report, id, renderFunc) => {
+        const element = document.getElementById(`${id}: ${report.pcid}`);
+        const result =
+          element && (await translate(renderFunc(report, history)));
+        return { element, translated: result };
+      };
+
+      const sections = (
+        await Promise.all(
+          reports.flatMap(report => [
+            translateSection(report, "ice-stats", renderICEStats),
+            translateSection(report, "rtp-stats", renderRTPStats),
+            translateSection(report, "bandwidth-stats", renderBandwidthStats),
+            translateSection(report, "frame-stats", renderFrameRateStats),
+          ])
+        )
+      ).filter(({ element }) => element);
+
+      document.l10n.pauseObserving();
+      for (const { element, translated } of sections) {
+        element.replaceWith(translated);
+      }
+      document.l10n.resumeObserving();
+    },
+    500,
+    {}
+  );
+})();
+
+function renderPeerConnection(report) {
+  const { pcid, browserId, closed, timestamp, configuration } = report;
+
+  const pcDiv = renderElement("div", { className: "peer-connection" });
+  {
+    const id = pcid.match(/id=(\S+)/)[1];
+    const url = pcid.match(/url=([^)]+)/)[1];
+    const now = new Date(timestamp);
+
+    pcDiv.append(
+      closed
+        ? renderElement("h3", {}, "about-webrtc-connection-closed", {
+            "browser-id": browserId,
+            id,
+            url,
+            now,
+          })
+        : renderElement("h3", {}, "about-webrtc-connection-open", {
+            "browser-id": browserId,
+            id,
+            url,
+            now,
+          })
+    );
+    pcDiv.append(new ShowTab(browserId).render()[0]);
+  }
+  {
+    const section = renderFoldableSection(pcDiv);
+    section.append(
+      renderElements("div", {}, [
+        renderElement(
+          "span",
+          {
+            className: "info-label",
+          },
+          "about-webrtc-peerconnection-id-label"
+        ),
+        renderText("span", pcid, { className: "info-body" }),
+      ]),
+      renderConfiguration(configuration),
+      renderRTPStats(report),
+      renderICEStats(report),
+      renderSDPStats(report),
+      renderBandwidthStats(report),
+      renderFrameRateStats(report)
+    );
+    pcDiv.append(section);
+  }
+  return pcDiv;
+}
+
+function renderSDPStats({ offerer, localSdp, remoteSdp, sdpHistory }) {
+  const trimNewlines = sdp => sdp.replaceAll("\r\n", "\n");
+
+  const statsDiv = renderElements("div", {}, [
+    renderElement("h4", {}, "about-webrtc-sdp-heading"),
+    renderElement(
+      "h5",
+      {},
+      offerer
+        ? "about-webrtc-local-sdp-heading-offer"
+        : "about-webrtc-local-sdp-heading-answer"
+    ),
+    renderText("pre", trimNewlines(localSdp)),
+    renderElement(
+      "h5",
+      {},
+      offerer
+        ? "about-webrtc-remote-sdp-heading-answer"
+        : "about-webrtc-remote-sdp-heading-offer"
+    ),
+    renderText("pre", trimNewlines(remoteSdp)),
+    renderElement("h4", {}, "about-webrtc-sdp-history-heading"),
+  ]);
+
+  // All SDP in sequential order. Add onclick handler to scroll the associated
+  // SDP into view below.
+  for (const { isLocal, timestamp } of sdpHistory) {
+    const histDiv = renderElement("div", {});
+    const text = renderElement(
+      "h5",
+      { className: "sdp-history-link" },
+      isLocal
+        ? "about-webrtc-sdp-set-at-timestamp-local"
+        : "about-webrtc-sdp-set-at-timestamp-remote",
+      { timestamp }
+    );
+    text.onclick = () => {
+      const elem = document.getElementById("sdp-history: " + timestamp);
+      if (elem) {
+        elem.scrollIntoView();
+      }
+    };
+    histDiv.append(text);
+    statsDiv.append(histDiv);
+  }
+
+  // Render the SDP into separate columns for local and remote.
+  const section = renderElement("div", { className: "sdp-history" });
+  const localDiv = renderElements("div", {}, [
+    renderElement("h4", {}, "about-webrtc-local-sdp-heading"),
+  ]);
+  const remoteDiv = renderElements("div", {}, [
+    renderElement("h4", {}, "about-webrtc-remote-sdp-heading"),
+  ]);
+
+  let first = NaN;
+  for (const { isLocal, timestamp, sdp, errors } of sdpHistory) {
+    if (isNaN(first)) {
+      first = timestamp;
+    }
+    const histDiv = isLocal ? localDiv : remoteDiv;
+    histDiv.append(
+      renderElement(
+        "h5",
+        { id: "sdp-history: " + timestamp },
+        "about-webrtc-sdp-set-timestamp",
+        { timestamp, "relative-timestamp": timestamp - first }
+      )
+    );
+    if (errors.length) {
+      histDiv.append(
+        renderElement("h5", {}, "about-webrtc-sdp-parsing-errors-heading")
+      );
+    }
+    for (const { lineNumber, error } of errors) {
+      histDiv.append(renderElement("br"), `${lineNumber}: ${error}`);
+    }
+    histDiv.append(renderText("pre", trimNewlines(sdp)));
+  }
+  section.append(localDiv, remoteDiv);
+  statsDiv.append(section);
+  return statsDiv;
+}
+
+function renderBandwidthStats(report) {
+  const statsDiv = renderElement("div", {
+    id: "bandwidth-stats: " + report.pcid,
+  });
+  const table = renderSimpleTable(
+    "",
+    [
+      "about-webrtc-track-identifier",
+      "about-webrtc-send-bandwidth-bytes-sec",
+      "about-webrtc-receive-bandwidth-bytes-sec",
+      "about-webrtc-max-padding-bytes-sec",
+      "about-webrtc-pacer-delay-ms",
+      "about-webrtc-round-trip-time-ms",
+    ],
+    report.bandwidthEstimations.map(stat => [
+      stat.trackIdentifier,
+      stat.sendBandwidthBps,
+      stat.receiveBandwidthBps,
+      stat.maxPaddingBps,
+      stat.pacerDelayMs,
+      stat.rttMs,
+    ])
+  );
+  statsDiv.append(
+    renderElement("h4", {}, "about-webrtc-bandwidth-stats-heading"),
+    table
+  );
+  return statsDiv;
+}
+
+function renderFrameRateStats(report) {
+  const statsDiv = renderElement("div", { id: "frame-stats: " + report.pcid });
+  report.videoFrameHistories.forEach(history => {
+    const stats = history.entries.map(stat => {
+      stat.elapsed = stat.lastFrameTimestamp - stat.firstFrameTimestamp;
+      if (stat.elapsed < 1) {
+        stat.elapsed = "0.00";
+      }
+      stat.elapsed = (stat.elapsed / 1_000).toFixed(3);
+      if (stat.elapsed && stat.consecutiveFrames) {
+        stat.avgFramerate = (stat.consecutiveFrames / stat.elapsed).toFixed(2);
+      } else {
+        stat.avgFramerate = "0.00";
+      }
+      return stat;
+    });
+
+    const table = renderSimpleTable(
+      "",
+      [
+        "about-webrtc-width-px",
+        "about-webrtc-height-px",
+        "about-webrtc-consecutive-frames",
+        "about-webrtc-time-elapsed",
+        "about-webrtc-estimated-framerate",
+        "about-webrtc-rotation-degrees",
+        "about-webrtc-first-frame-timestamp",
+        "about-webrtc-last-frame-timestamp",
+        "about-webrtc-local-receive-ssrc",
+        "about-webrtc-remote-send-ssrc",
+      ],
+      stats.map(stat =>
+        [
+          stat.width,
+          stat.height,
+          stat.consecutiveFrames,
+          stat.elapsed,
+          stat.avgFramerate,
+          stat.rotationAngle,
+          stat.firstFrameTimestamp,
+          stat.lastFrameTimestamp,
+          stat.localSsrc,
+          stat.remoteSsrc || "?",
+        ].map(entry => (Object.is(entry, undefined) ? "<<undefined>>" : entry))
+      )
+    );
+
+    statsDiv.append(
+      renderElement("h4", {}, "about-webrtc-frame-stats-heading", {
+        "track-identifier": history.trackIdentifier,
+      }),
+      table
+    );
+  });
+
+  return statsDiv;
+}
+
+function renderRTPStats(report, history) {
+  const rtpStats = [
+    ...(report.inboundRtpStreamStats || []),
+    ...(report.outboundRtpStreamStats || []),
+  ];
+  const remoteRtpStats = [
+    ...(report.remoteInboundRtpStreamStats || []),
+    ...(report.remoteOutboundRtpStreamStats || []),
+  ];
+
+  // Generate an id-to-streamStat index for each remote streamStat. This will
+  // be used next to link the remote to its local side.
+  const remoteRtpStatsMap = {};
+  for (const stat of remoteRtpStats) {
+    remoteRtpStatsMap[stat.id] = stat;
+  }
+
+  // If a streamStat has a remoteId attribute, create a remoteRtpStats
+  // attribute that references the remote streamStat entry directly.
+  // That is, the index generated above is merged into the returned list.
+  for (const stat of rtpStats.filter(s => "remoteId" in s)) {
+    stat.remoteRtpStats = remoteRtpStatsMap[stat.remoteId];
+  }
+  for (const stat of rtpStats.filter(s => "codecId" in s)) {
+    stat.codecStat = report.codecStats.find(({ id }) => id == stat.codecId);
+  }
+
+  // Render stats set
+  return renderElements("div", { id: "rtp-stats: " + report.pcid }, [
+    renderElement("h4", {}, "about-webrtc-rtp-stats-heading"),
+    ...rtpStats.map(stat => {
+      const { ssrc, remoteId, remoteRtpStats } = stat;
+      const div = renderElements("div", {}, [
+        renderText("h5", `SSRC ${ssrc}`),
+        renderCodecStats(stat),
+        renderTransportStats(stat, true, history),
+      ]);
+      if (remoteId && remoteRtpStats) {
+        div.append(renderTransportStats(remoteRtpStats, false));
+      }
+      return div;
+    }),
+  ]);
+}
+
+function renderCodecStats({
+  codecStat,
+  framesEncoded,
+  framesDecoded,
+  framesDropped,
+  discardedPackets,
+  packetsReceived,
+}) {
+  let elements = [];
+
+  if (codecStat) {
+    elements.push(
+      renderText("span", `${codecStat.payloadType} ${codecStat.mimeType}`, {})
+    );
+    if (framesEncoded !== undefined || framesDecoded !== undefined) {
+      elements.push(
+        renderElement(
+          "span",
+          { className: "stat-label" },
+          "about-webrtc-frames",
+          {
+            frames: framesEncoded || framesDecoded || 0,
+          }
+        )
+      );
+    }
+    if (codecStat.channels !== undefined) {
+      elements.push(
+        renderElement(
+          "span",
+          { className: "stat-label" },
+          "about-webrtc-channels",
+          {
+            channels: codecStat.channels,
+          }
+        )
+      );
+    }
+    elements.push(
+      renderText(
+        "span",
+        ` ${codecStat.clockRate} ${codecStat.sdpFmtpLine || ""}`,
+        {}
+      )
+    );
+  }
+  if (framesDropped !== undefined) {
+    elements.push(
+      renderElement(
+        "span",
+        { className: "stat-label" },
+        "about-webrtc-dropped-frames-label"
+      )
+    );
+    elements.push(renderText("span", ` ${framesDropped}`, {}));
+  }
+  if (discardedPackets !== undefined) {
+    elements.push(
+      renderElement(
+        "span",
+        { className: "stat-label" },
+        "about-webrtc-discarded-packets-label"
+      )
+    );
+    elements.push(renderText("span", ` ${discardedPackets}`, {}));
+  }
+  if (elements.length) {
+    if (packetsReceived !== undefined) {
+      elements.unshift(
+        renderElement("span", {}, "about-webrtc-decoder-label"),
+        renderText("span", ": ")
+      );
+    } else {
+      elements.unshift(
+        renderElement("span", {}, "about-webrtc-encoder-label"),
+        renderText("span", ": ")
+      );
+    }
+  }
+  return renderElements("div", {}, elements);
+}
+
+function renderTransportStats(
+  {
+    id,
+    timestamp,
+    type,
+    packetsReceived,
+    bytesReceived,
+    packetsLost,
+    jitter,
+    roundTripTime,
+    packetsSent,
+    bytesSent,
+  },
+  local,
+  history
+) {
+  if (history) {
+    if (history[id] === undefined) {
+      history[id] = {};
+    }
+  }
+
+  const estimateKBps = (timestamp, lastTimestamp, bytes, lastBytes) => {
+    if (!timestamp || !lastTimestamp || !bytes || !lastBytes) {
+      return "0.0";
+    }
+    const elapsedTime = timestamp - lastTimestamp;
+    if (elapsedTime <= 0) {
+      return "0.0";
+    }
+    return ((bytes - lastBytes) / elapsedTime).toFixed(1);
+  };
+
+  let elements = [];
+
+  if (local) {
+    elements.push(
+      renderElement("span", {}, "about-webrtc-type-local"),
+      renderText("span", ": ")
+    );
+  } else {
+    elements.push(
+      renderElement("span", {}, "about-webrtc-type-remote"),
+      renderText("span", ": ")
+    );
+  }
+
+  const time = new Date(timestamp).toTimeString();
+  elements.push(renderText("span", `${time} ${type}`));
+
+  if (packetsReceived) {
+    elements.push(
+      renderElement(
+        "span",
+        { className: "stat-label" },
+        "about-webrtc-received-label",
+        {
+          packets: packetsReceived,
+        }
+      )
+    );
+
+    if (bytesReceived) {
+      let s = ` (${(bytesReceived / 1024).toFixed(2)} Kb`;
+      if (local && history) {
+        s += ` , ${estimateKBps(
+          timestamp,
+          history[id].lastTimestamp,
+          bytesReceived,
+          history[id].lastBytesReceived
+        )} KBps`;
+      }
+      s += ")";
+      elements.push(renderText("span", s));
+    }
+
+    elements.push(
+      renderElement(
+        "span",
+        { className: "stat-label" },
+        "about-webrtc-lost-label",
+        {
+          packets: packetsLost,
+        }
+      )
+    );
+    elements.push(
+      renderElement(
+        "span",
+        { className: "stat-label" },
+        "about-webrtc-jitter-label",
+        {
+          jitter,
+        }
+      )
+    );
+
+    if (roundTripTime) {
+      elements.push(renderText("span", ` RTT: ${roundTripTime * 1000} ms`));
+    }
+  } else if (packetsSent) {
+    elements.push(
+      renderElement(
+        "span",
+        { className: "stat-label" },
+        "about-webrtc-sent-label",
+        {
+          packets: packetsSent,
+        }
+      )
+    );
+    if (bytesSent) {
+      let s = ` (${(bytesSent / 1024).toFixed(2)} Kb`;
+      if (local && history) {
+        s += `, ${estimateKBps(
+          timestamp,
+          history[id].lastTimestamp,
+          bytesSent,
+          history[id].lastBytesSent
+        )} KBps`;
+      }
+      s += ")";
+      elements.push(renderText("span", s));
+    }
+  }
+
+  // Update history
+  if (history) {
+    history[id].lastBytesReceived = bytesReceived;
+    history[id].lastBytesSent = bytesSent;
+    history[id].lastTimestamp = timestamp;
+  }
+
+  return renderElements("div", {}, elements);
+}
+
+function renderRawIceTable(caption, candidates) {
+  const table = renderSimpleTable(
+    "",
+    [caption],
+    [...new Set(candidates.sort())].filter(i => i).map(i => [i])
+  );
+  table.className = "raw-candidate";
+  return table;
+}
+
+function renderConfiguration(c) {
+  const provided = "about-webrtc-configuration-element-provided";
+  const notProvided = "about-webrtc-configuration-element-not-provided";
+
+  // Create the text for a configuration field
+  const cfg = (obj, key) => [
+    renderElement("br"),
+    `${key}: `,
+    key in obj ? obj[key] : renderElement("i", {}, notProvided),
+  ];
+
+  // Create the text for a fooProvided configuration field
+  const pro = (obj, key) => [
+    renderElement("br"),
+    `${key}(`,
+    renderElement("i", {}, provided),
+    `/`,
+    renderElement("i", {}, notProvided),
+    `): `,
+    renderElement("i", {}, obj[`${key}Provided`] ? provided : notProvided),
+  ];
+
+  return renderElements("div", { classList: "peer-connection-config" }, [
+    "RTCConfiguration",
+    ...cfg(c, "bundlePolicy"),
+    ...cfg(c, "iceTransportPolicy"),
+    ...pro(c, "peerIdentity"),
+    ...cfg(c, "sdpSemantics"),
+    renderElement("br"),
+    "iceServers: ",
+    ...(!c.iceServers
+      ? [renderElement("i", {}, notProvided)]
+      : c.iceServers.map(i =>
+          renderElements("div", {}, [
+            `urls: ${JSON.stringify(i.urls)}`,
+            ...pro(i, "credential"),
+            ...pro(i, "userName"),
+          ])
+        )),
+  ]);
+}
+
+function renderICEStats(report) {
+  const iceDiv = renderElements("div", { id: "ice-stats: " + report.pcid }, [
+    renderElement("h4", {}, "about-webrtc-ice-stats-heading"),
+  ]);
+
+  // Render ICECandidate table
+  {
+    const caption = renderElement(
+      "caption",
+      { className: "no-print" },
+      "about-webrtc-trickle-caption-msg"
+    );
+
+    // Generate ICE stats
+    const stats = [];
+    {
+      // Create an index based on candidate ID for each element in the
+      // iceCandidateStats array.
+      const candidates = {};
+      for (const candidate of report.iceCandidateStats) {
+        candidates[candidate.id] = candidate;
+      }
+
+      // a method to see if a given candidate id is in the array of tickled
+      // candidates.
+      const isTrickled = candidateId =>
+        report.trickledIceCandidateStats.some(({ id }) => id == candidateId);
+
+      // A component may have a remote or local candidate address or both.
+      // Combine those with both; these will be the peer candidates.
+      const matched = {};
+
+      for (const {
+        localCandidateId,
+        remoteCandidateId,
+        componentId,
+        state,
+        priority,
+        nominated,
+        selected,
+        bytesSent,
+        bytesReceived,
+      } of report.iceCandidatePairStats) {
+        const local = candidates[localCandidateId];
+        if (local) {
+          const stat = {
+            ["local-candidate"]: candidateToString(local),
+            componentId,
+            state,
+            priority,
+            nominated,
+            selected,
+            bytesSent,
+            bytesReceived,
+          };
+          matched[local.id] = true;
+          if (isTrickled(local.id)) {
+            stat["local-trickled"] = true;
+          }
+
+          const remote = candidates[remoteCandidateId];
+          if (remote) {
+            stat["remote-candidate"] = candidateToString(remote);
+            matched[remote.id] = true;
+            if (isTrickled(remote.id)) {
+              stat["remote-trickled"] = true;
+            }
+          }
+          stats.push(stat);
+        }
+      }
+
+      // sort (group by) componentId first, then bytesSent if available, else by
+      // priority
+      stats.sort((a, b) => {
+        if (a.componentId != b.componentId) {
+          return a.componentId - b.componentId;
+        }
+        return b.bytesSent
+          ? b.bytesSent - (a.bytesSent || 0)
+          : (b.priority || 0) - (a.priority || 0);
+      });
+    }
+    // Render ICE stats
+    // don't use |stat.x || ""| here because it hides 0 values
+    const statsTable = renderSimpleTable(
+      caption,
+      [
+        "about-webrtc-ice-state",
+        "about-webrtc-nominated",
+        "about-webrtc-selected",
+        "about-webrtc-local-candidate",
+        "about-webrtc-remote-candidate",
+        "about-webrtc-ice-component-id",
+        "about-webrtc-priority",
+        "about-webrtc-ice-pair-bytes-sent",
+        "about-webrtc-ice-pair-bytes-received",
+      ],
+      stats.map(stat =>
+        [
+          stat.state,
+          stat.nominated,
+          stat.selected,
+          stat["local-candidate"],
+          stat["remote-candidate"],
+          stat.componentId,
+          stat.priority,
+          stat.bytesSent,
+          stat.bytesReceived,
+        ].map(entry => (Object.is(entry, undefined) ? "" : entry))
+      )
+    );
+
+    // after rendering the table, we need to change the class name for each
+    // candidate pair's local or remote candidate if it was trickled.
+    let index = 0;
+    for (const {
+      state,
+      nominated,
+      selected,
+      "local-trickled": localTrickled,
+      "remote-trickled": remoteTrickled,
+    } of stats) {
+      // look at statsTable row index + 1 to skip column headers
+      const { cells } = statsTable.rows[++index];
+      cells[0].className = `ice-${state}`;
+      if (nominated) {
+        cells[1].className = "ice-succeeded";
+      }
+      if (selected) {
+        cells[2].className = "ice-succeeded";
+      }
+      if (localTrickled) {
+        cells[3].className = "ice-trickled";
+      }
+      if (remoteTrickled) {
+        cells[4].className = "ice-trickled";
+      }
+    }
+
+    // if the current row's component id changes, mark the bottom of the
+    // previous row with a thin, black border to differentiate the
+    // component id grouping.
+    let previousRow;
+    for (const row of statsTable.rows) {
+      if (previousRow) {
+        if (previousRow.cells[5].innerHTML != row.cells[5].innerHTML) {
+          previousRow.className = "bottom-border";
+        }
+      }
+      previousRow = row;
+    }
+    iceDiv.append(statsTable);
+  }
+  // restart/rollback counts.
+  iceDiv.append(
+    renderIceMetric("about-webrtc-ice-restart-count-label", report.iceRestarts),
+    renderIceMetric(
+      "about-webrtc-ice-rollback-count-label",
+      report.iceRollbacks
+    )
+  );
+
+  // Render raw ICECandidate section
+  {
+    const section = renderElements("div", {}, [
+      renderElement("h4", {}, "about-webrtc-raw-candidates-heading"),
+    ]);
+    const foldSection = renderFoldableSection(section, {
+      showMsg: "about-webrtc-raw-cand-show-msg",
+      hideMsg: "about-webrtc-raw-cand-hide-msg",
+    });
+
+    // render raw candidates
+    foldSection.append(
+      renderElements("div", {}, [
+        renderRawIceTable(
+          "about-webrtc-raw-local-candidate",
+          report.rawLocalCandidates
+        ),
+        renderRawIceTable(
+          "about-webrtc-raw-remote-candidate",
+          report.rawRemoteCandidates
+        ),
+      ])
+    );
+    section.append(foldSection);
+    iceDiv.append(section);
+  }
+  return iceDiv;
+}
+
+function renderIceMetric(label, value) {
+  return renderElements("div", {}, [
+    renderElement("span", { className: "info-label" }, label),
+    renderText("span", value, { className: "info-body" }),
+  ]);
+}
+
+function candidateToString({
+  type,
+  address,
+  port,
+  protocol,
+  candidateType,
+  relayProtocol,
+  proxied,
+} = {}) {
+  if (!type) {
+    return "*";
+  }
+  if (relayProtocol) {
+    candidateType = `${candidateType}-${relayProtocol}`;
+  }
+  proxied = type == "local-candidate" ? ` [${proxied}]` : "";
+  return `${address}:${port}/${protocol}(${candidateType})${proxied}`;
+}
+
+function renderUserPrefs() {
+  const getPref = key => {
+    switch (Services.prefs.getPrefType(key)) {
+      case Services.prefs.PREF_BOOL:
+        return Services.prefs.getBoolPref(key);
+      case Services.prefs.PREF_INT:
+        return Services.prefs.getIntPref(key);
+      case Services.prefs.PREF_STRING:
+        return Services.prefs.getStringPref(key);
+    }
+    return "";
+  };
+  const prefs = [
+    "media.peerconnection",
+    "media.navigator",
+    "media.getusermedia",
+    "media.gmp-gmpopenh264.enabled",
+  ];
+  const renderPref = p => renderText("p", `${p}: ${getPref(p)}`);
+  const display = prefs
+    .flatMap(Services.prefs.getChildList)
+    .filter(Services.prefs.prefHasUserValue)
+    .map(renderPref);
+  return renderElements(
+    "div",
+    {
+      id: "prefs",
+      className: "prefs",
+      style: display.length ? "" : "visibility:hidden",
+    },
+    [
+      renderElements("span", { className: "section-heading" }, [
+        renderElement(
+          "h3",
+          {},
+          "about-webrtc-custom-webrtc-configuration-heading"
+        ),
+      ]),
+      ...display,
+    ]
+  );
+}
+
+function renderFoldableSection(parent, options = {}) {
+  const section = renderElement("div");
+  if (parent) {
+    const ctrl = renderElements("div", { className: "section-ctrl no-print" }, [
+      new FoldEffect(section, options).render(),
+    ]);
+    parent.append(ctrl);
+  }
+  return section;
+}
+
+function renderSimpleTable(caption, headings, data) {
+  const heads = headings.map(text => renderElement("th", {}, text));
+  const renderCell = text => renderText("td", text);
+
+  return renderElements("table", {}, [
+    caption,
+    renderElements("tr", {}, heads),
+    ...data.map(line => renderElements("tr", {}, line.map(renderCell))),
+  ]);
+}
+
+class FoldEffect {
+  constructor(
+    target,
+    {
+      showMsg = "about-webrtc-fold-show-msg",
+      hideMsg = "about-webrtc-fold-hide-msg",
+    } = {}
+  ) {
+    Object.assign(this, { target, showMsg, hideMsg });
+  }
+
+  render() {
+    this.target.classList.add("fold-target");
+    this.trigger = renderElement("div", { className: "fold-trigger" });
+    this.trigger.classList.add(this.showMsg, this.hideMsg);
+    this.collapse();
+    this.trigger.onclick = () => {
+      if (this.target.classList.contains("fold-closed")) {
+        this.expand();
+      } else {
+        this.collapse();
+      }
+    };
+    return this.trigger;
+  }
+
+  expand() {
+    this.target.classList.remove("fold-closed");
+    document.l10n.setAttributes(this.trigger, this.hideMsg);
+  }
+
+  collapse() {
+    this.target.classList.add("fold-closed");
+    document.l10n.setAttributes(this.trigger, this.showMsg);
+  }
+
+  static expandAll() {
+    for (const target of document.getElementsByClassName("fold-closed")) {
+      target.classList.remove("fold-closed");
+    }
+    for (const trigger of document.getElementsByClassName("fold-trigger")) {
+      const hideMsg = trigger.classList[2];
+      document.l10n.setAttributes(trigger, hideMsg);
+    }
+  }
+
+  static collapseAll() {
+    for (const target of document.getElementsByClassName("fold-target")) {
+      target.classList.add("fold-closed");
+    }
+    for (const trigger of document.getElementsByClassName("fold-trigger")) {
+      const showMsg = trigger.classList[1];
+      document.l10n.setAttributes(trigger, showMsg);
+    }
+  }
+}