Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

11 files changed, 1442 insertions, 0 deletions

diff --git a/toolkit/components/aboutprocesses/tests/browser/browser.toml b/toolkit/components/aboutprocesses/tests/browser/browser.toml
new file mode 100644
index 0000000000..07bec9de5e
--- /dev/null
+++ b/toolkit/components/aboutprocesses/tests/browser/browser.toml
@@ -0,0 +1,32 @@
+[DEFAULT]
+head = "head.js"
+skip-if = [
+  "asan",
+  "tsan"
+] # With sanitizers, we regularly hit internal timeouts.
+support-files = ["small-shot.mp3"]
+
+["browser_aboutprocesses_default_options.js"]
+fail-if = ["a11y_checks"] # Bug 1854228 td.action-icon, td.close-icon may not be focusable
+https_first_disabled = true
+
+["browser_aboutprocesses_selection.js"]
+fail-if = ["a11y_checks"] # Bug 1854228 tr.process, tr.window, tr.thread, tr.thread-summary may not be focusable
+
+["browser_aboutprocesses_shortcut.js"]
+
+["browser_aboutprocesses_show_all_frames.js"]
+fail-if = ["a11y_checks"] # Bug 1854228 td.action-icon, td.close-icon may not be focusable
+https_first_disabled = true
+
+["browser_aboutprocesses_show_frames_without_threads.js"]
+fail-if = ["a11y_checks"] # Bug 1854228 td.action-icon, td.close-icon may not be focusable
+https_first_disabled = true
+
+["browser_aboutprocesses_show_threads.js"]
+fail-if = ["a11y_checks"] # Bug 1854228 td.action-icon, td.close-icon may not be focusable
+https_first_disabled = true
+
+["browser_aboutprocesses_twisty.js"]
+
+["browser_aboutprocesses_utility_actors.js"]
diff --git a/toolkit/components/aboutprocesses/tests/browser/browser_aboutprocesses_default_options.js b/toolkit/components/aboutprocesses/tests/browser/browser_aboutprocesses_default_options.js
new file mode 100644
index 0000000000..15ed1c4501
--- /dev/null
+++ b/toolkit/components/aboutprocesses/tests/browser/browser_aboutprocesses_default_options.js
@@ -0,0 +1,7 @@
+// Test about:processes with default options.
+add_task(async function testDefaultOptions() {
+  return testAboutProcessesWithConfig({
+    showAllFrames: false,
+    showThreads: false,
+  });
+});
diff --git a/toolkit/components/aboutprocesses/tests/browser/browser_aboutprocesses_selection.js b/toolkit/components/aboutprocesses/tests/browser/browser_aboutprocesses_selection.js
new file mode 100644
index 0000000000..f208fb095d
--- /dev/null
+++ b/toolkit/components/aboutprocesses/tests/browser/browser_aboutprocesses_selection.js
@@ -0,0 +1,124 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+var doc, tbody, tabAboutProcesses;
+
+const rowTypes = ["process", "window", "thread-summary", "thread"];
+
+function promiseUpdate() {
+  return promiseAboutProcessesUpdated({
+    doc,
+    tbody,
+    force: true,
+    tabAboutProcesses,
+  });
+}
+
+add_setup(async function () {
+  Services.prefs.setBoolPref("toolkit.aboutProcesses.showThreads", true);
+
+  info("Setting up about:processes");
+  tabAboutProcesses = await BrowserTestUtils.openNewForegroundTab({
+    gBrowser,
+    opening: "about:processes",
+    waitForLoad: true,
+  });
+
+  doc = tabAboutProcesses.linkedBrowser.contentDocument;
+  tbody = doc.getElementById("process-tbody");
+  await promiseUpdate();
+
+  info("Open a list of threads to have thread rows displayed");
+  let twisty = doc.querySelector("tr.thread-summary .twisty");
+  twisty.click();
+  await promiseUpdate();
+});
+
+add_task(async function testSelectionPersistedAfterUpdate() {
+  for (let rowType of rowTypes) {
+    let row = doc.querySelector(`tr.${rowType}`);
+    Assert.ok(!!row, `Found ${rowType} row`);
+    Assert.ok(!row.hasAttribute("selected"), "The row should not be selected");
+
+    info("Click in the row to select it.");
+    row.click();
+    Assert.equal(
+      row.getAttribute("selected"),
+      "true",
+      "The row should be selected"
+    );
+    Assert.equal(
+      doc.querySelectorAll("[selected]").length,
+      1,
+      "There should be only one selected row"
+    );
+
+    info("Wait for an update and ensure the selected row is still the same");
+    let rowId = row.rowId;
+    let findRowsWithId = rowId =>
+      [...doc.querySelectorAll("tr")].filter(r => r.rowId == rowId);
+    Assert.equal(
+      findRowsWithId(rowId).length,
+      1,
+      "There should be only one row with id " + rowId
+    );
+    await promiseUpdate();
+    let selectedRow = doc.querySelector("[selected]");
+    if (rowType == "thread" && !selectedRow) {
+      info("The thread row might have disappeared if the thread has ended");
+      Assert.equal(
+        findRowsWithId(rowId).length,
+        0,
+        "There should no longer be a row with id " + rowId
+      );
+      continue;
+    }
+    Assert.ok(
+      !!selectedRow,
+      "There should still be a selected row after an update"
+    );
+    Assert.equal(
+      selectedRow.rowId,
+      rowId,
+      "The selected row should have the same id as the row we clicked"
+    );
+  }
+});
+
+add_task(function testClickAgainToRemoveSelection() {
+  for (let rowType of rowTypes) {
+    let row = doc.querySelector(`tr.${rowType}`);
+    Assert.ok(!!row, `Found ${rowType} row`);
+    Assert.ok(!row.hasAttribute("selected"), "The row should not be selected");
+    info("Click in the row to select it.");
+    row.click();
+    Assert.equal(
+      row.getAttribute("selected"),
+      "true",
+      "The row should now be selected"
+    );
+    Assert.equal(
+      doc.querySelectorAll("[selected]").length,
+      1,
+      "There should be only one selected row"
+    );
+
+    info("Click the row again to remove the selection.");
+    row.click();
+    Assert.ok(
+      !row.hasAttribute("selected"),
+      "The row should no longer be selected"
+    );
+    Assert.ok(
+      !doc.querySelector("[selected]"),
+      "There should be no selected row"
+    );
+  }
+});
+
+add_task(function cleanup() {
+  BrowserTestUtils.removeTab(tabAboutProcesses);
+  Services.prefs.clearUserPref("toolkit.aboutProcesses.showThreads");
+});
diff --git a/toolkit/components/aboutprocesses/tests/browser/browser_aboutprocesses_shortcut.js b/toolkit/components/aboutprocesses/tests/browser/browser_aboutprocesses_shortcut.js
new file mode 100644
index 0000000000..61b8be1fcd
--- /dev/null
+++ b/toolkit/components/aboutprocesses/tests/browser/browser_aboutprocesses_shortcut.js
@@ -0,0 +1,16 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+add_task(async function () {
+  // Wait for the browser to be ready to receive keyboard events.
+  if (!gBrowser.selectedBrowser.hasLayers) {
+    await BrowserTestUtils.waitForEvent(window, "MozLayerTreeReady");
+  }
+
+  EventUtils.synthesizeKey("KEY_Escape", { shiftKey: true });
+
+  await BrowserTestUtils.browserLoaded(gBrowser.selectedBrowser);
+  Assert.equal(gBrowser.selectedBrowser.currentURI.spec, "about:processes");
+});
diff --git a/toolkit/components/aboutprocesses/tests/browser/browser_aboutprocesses_show_all_frames.js b/toolkit/components/aboutprocesses/tests/browser/browser_aboutprocesses_show_all_frames.js
new file mode 100644
index 0000000000..2c437f9dc4
--- /dev/null
+++ b/toolkit/components/aboutprocesses/tests/browser/browser_aboutprocesses_show_all_frames.js
@@ -0,0 +1,6 @@
+add_task(async function testShowFramesAndThreads() {
+  await testAboutProcessesWithConfig({
+    showAllFrames: true,
+    showThreads: true,
+  });
+});
diff --git a/toolkit/components/aboutprocesses/tests/browser/browser_aboutprocesses_show_frames_without_threads.js b/toolkit/components/aboutprocesses/tests/browser/browser_aboutprocesses_show_frames_without_threads.js
new file mode 100644
index 0000000000..178ceec9ed
--- /dev/null
+++ b/toolkit/components/aboutprocesses/tests/browser/browser_aboutprocesses_show_frames_without_threads.js
@@ -0,0 +1,6 @@
+add_task(async function testShowFramesWithoutThreads() {
+  await testAboutProcessesWithConfig({
+    showAllFrames: true,
+    showThreads: false,
+  });
+});
diff --git a/toolkit/components/aboutprocesses/tests/browser/browser_aboutprocesses_show_threads.js b/toolkit/components/aboutprocesses/tests/browser/browser_aboutprocesses_show_threads.js
new file mode 100644
index 0000000000..10e630ab31
--- /dev/null
+++ b/toolkit/components/aboutprocesses/tests/browser/browser_aboutprocesses_show_threads.js
@@ -0,0 +1,7 @@
+// Test about:processes with showThreads: true, showAllFrames: false.
+add_task(async function testShowThreads() {
+  return testAboutProcessesWithConfig({
+    showAllFrames: false,
+    showThreads: true,
+  });
+});
diff --git a/toolkit/components/aboutprocesses/tests/browser/browser_aboutprocesses_twisty.js b/toolkit/components/aboutprocesses/tests/browser/browser_aboutprocesses_twisty.js
new file mode 100644
index 0000000000..77fb0fbfbb
--- /dev/null
+++ b/toolkit/components/aboutprocesses/tests/browser/browser_aboutprocesses_twisty.js
@@ -0,0 +1,134 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+let doc, tbody, tabAboutProcesses;
+
+const rowTypes = ["process", "window", "thread-summary", "thread"];
+
+function promiseUpdate() {
+  return promiseAboutProcessesUpdated({
+    doc,
+    tbody,
+    force: true,
+    tabAboutProcesses,
+  });
+}
+
+add_setup(async function () {
+  Services.prefs.setBoolPref("toolkit.aboutProcesses.showThreads", true);
+
+  info("Setting up about:processes");
+  tabAboutProcesses = await BrowserTestUtils.openNewForegroundTab({
+    gBrowser,
+    opening: "about:processes",
+    waitForLoad: true,
+  });
+
+  doc = tabAboutProcesses.linkedBrowser.contentDocument;
+  tbody = doc.getElementById("process-tbody");
+  await promiseUpdate();
+});
+
+add_task(function testTwistyImageButtonSetup() {
+  let twistyBtn = doc.querySelector("tr.thread-summary .twisty");
+  let groupRow = twistyBtn.parentNode.parentNode;
+  let groupRowId = groupRow.firstChild.children[1].getAttribute("id");
+  let groupRowLabelId = groupRowId.split(":")[1];
+
+  info("Verify twisty button is properly set up.");
+  Assert.ok(
+    twistyBtn.hasAttribute("aria-labelledby"),
+    "the Twisty image button has an aria-labelledby"
+  );
+  Assert.equal(
+    twistyBtn.getAttribute("aria-labelledby"),
+    `${groupRowLabelId}-label ${groupRowId}`,
+    "the Twisty image button's aria-labelledby refers to a valid 'id' that is the Name of its row"
+  );
+  Assert.equal(
+    twistyBtn.getAttribute("role"),
+    "button",
+    "the Twisty image is programmatically a button"
+  );
+  Assert.equal(
+    twistyBtn.getAttribute("tabindex"),
+    "0",
+    "the Twisty image button is included in the focus order"
+  );
+  Assert.equal(
+    twistyBtn.getAttribute("aria-expanded"),
+    "false",
+    "the Twisty image button is collapsed by default"
+  );
+});
+
+add_task(function testTwistyImageButtonClicking() {
+  let twistyBtn = doc.querySelector("tr.thread-summary .twisty");
+  let groupRow = twistyBtn.parentNode.parentNode;
+
+  info(
+    "Verify we can toggle/open a list of threads by clicking the twisty button."
+  );
+  twistyBtn.click();
+
+  Assert.ok(
+    groupRow.nextSibling.classList.contains("thread") &&
+      !groupRow.nextSibling.classList.contains("thread-summary"),
+    "clicking a collapsed Twisty adds subitems after the row"
+  );
+  Assert.equal(
+    twistyBtn.getAttribute("aria-expanded"),
+    "true",
+    "the Twisty image button is expanded after a click"
+  );
+});
+
+add_task(function testTwistyImageButtonKeypressing() {
+  let twistyBtn = doc.querySelector("tr.thread-summary .twisty");
+  let groupRow = twistyBtn.parentNode.parentNode;
+
+  info(
+    `Verify we can toggle/close a list of threads by pressing Enter or
+    Space on the twisty button.`
+  );
+  // Verify the twisty button can be focused with a keyboard.
+  twistyBtn.focus();
+  Assert.equal(
+    twistyBtn,
+    doc.activeElement,
+    "the Twisty image button can be focused"
+  );
+
+  // Verify we can toggle subitems with a keyboard.
+  // Twisty is expanded
+  EventUtils.synthesizeKey("KEY_Enter");
+  Assert.ok(
+    !groupRow.nextSibling.classList.contains("thread") ||
+      groupRow.nextSibling.classList.contains("thread-summary"),
+    "pressing Enter on expanded Twisty hides a list of threads after the row"
+  );
+  Assert.equal(
+    twistyBtn.getAttribute("aria-expanded"),
+    "false",
+    "the Twisty image button is collapsed after an Enter keypress"
+  );
+  // Twisty is collapsed
+  EventUtils.synthesizeKey(" ");
+  Assert.ok(
+    groupRow.nextSibling.classList.contains("thread") &&
+      !groupRow.nextSibling.classList.contains("thread-summary"),
+    "pressing Space on collapsed Twisty shows a list of threads after the row"
+  );
+  Assert.equal(
+    twistyBtn.getAttribute("aria-expanded"),
+    "true",
+    "the Twisty image button is expanded after a Space keypress"
+  );
+});
+
+add_task(function cleanup() {
+  BrowserTestUtils.removeTab(tabAboutProcesses);
+  Services.prefs.clearUserPref("toolkit.aboutProcesses.showThreads");
+});
diff --git a/toolkit/components/aboutprocesses/tests/browser/browser_aboutprocesses_utility_actors.js b/toolkit/components/aboutprocesses/tests/browser/browser_aboutprocesses_utility_actors.js
new file mode 100644
index 0000000000..8ab7dcb747
--- /dev/null
+++ b/toolkit/components/aboutprocesses/tests/browser/browser_aboutprocesses_utility_actors.js
@@ -0,0 +1,44 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Test about:processes preparation of utility actor names.
+add_task(async function testUtilityActorNames() {
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      opening: "about:processes",
+      waitForLoad: true,
+    },
+    browser => {
+      const View = browser.contentWindow.View;
+      const unknownActorName = "unknown";
+      const kDontExistFluentName =
+        View.utilityActorNameToFluentName("i-dont-exist");
+      const unknownFluentName =
+        View.utilityActorNameToFluentName(unknownActorName);
+
+      Assert.equal(
+        unknownFluentName,
+        kDontExistFluentName,
+        "Anything is unknown"
+      );
+
+      for (let actorName of ChromeUtils.getAllPossibleUtilityActorNames()) {
+        const fluentName = View.utilityActorNameToFluentName(actorName);
+        if (actorName === unknownActorName) {
+          Assert.ok(
+            fluentName === unknownFluentName,
+            `Actor name ${actorName} is expected unknown ${fluentName}`
+          );
+        } else {
+          Assert.ok(
+            fluentName !== unknownFluentName,
+            `Actor name ${actorName} is known ${fluentName}`
+          );
+        }
+      }
+    }
+  );
+});
diff --git a/toolkit/components/aboutprocesses/tests/browser/head.js b/toolkit/components/aboutprocesses/tests/browser/head.js
new file mode 100644
index 0000000000..7f22825fa2
--- /dev/null
+++ b/toolkit/components/aboutprocesses/tests/browser/head.js
@@ -0,0 +1,1066 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// A bunch of assumptions we make about the behavior of the parent process,
+// and which we use as sanity checks. If Firefox evolves, we will need to
+// update these values.
+// Note that Test Verify can really stress the cpu durations.
+const HARDCODED_ASSUMPTIONS_PROCESS = {
+  minimalNumberOfThreads: 6,
+  maximalNumberOfThreads: 1000,
+  minimalCPUPercentage: 0,
+  maximalCPUPercentage: 1000,
+  minimalCPUTotalDurationMS: 10,
+  maximalCPUTotalDurationMS: 10000000,
+  minimalRAMBytesUsage: 1024 * 1024 /* 1 Megabyte */,
+  maximalRAMBytesUsage: 1024 * 1024 * 1024 * 1024 * 1 /* 1 Tb */,
+};
+
+const HARDCODED_ASSUMPTIONS_THREAD = {
+  minimalCPUPercentage: 0,
+  maximalCPUPercentage: 100,
+  minimalCPUTotalDurationMS: 0,
+  maximalCPUTotalDurationMS: 10000000,
+};
+
+// How close we accept our rounding up/down.
+const APPROX_FACTOR = 1.51;
+const MS_PER_NS = 1000000;
+
+// Wait for `about:processes` to be updated.
+async function promiseAboutProcessesUpdated({ doc, force, tabAboutProcesses }) {
+  let startTime = performance.now();
+
+  let updatePromise = new Promise(resolve => {
+    doc.addEventListener("AboutProcessesUpdated", resolve, { once: true });
+  });
+
+  if (force) {
+    await SpecialPowers.spawn(tabAboutProcesses.linkedBrowser, [], async () => {
+      info("Forcing about:processes refresh");
+      await content.Control.update(/* force = */ true);
+    });
+  }
+
+  await updatePromise;
+
+  // Fluent will update the visible table content during the next
+  // refresh driver tick, wait for it.
+  // requestAnimationFrame calls us at the begining of the tick, we use
+  // dispatchToMainThread to execute our code after the end of it.
+  //XXX: Replace with proper wait for l10n completion once bug 1520659 is fixed.
+  await new Promise(doc.defaultView.requestAnimationFrame);
+  await new Promise(resolve => Services.tm.dispatchToMainThread(resolve));
+
+  ChromeUtils.addProfilerMarker(
+    "promiseAboutProcessesUpdated",
+    { startTime, category: "Test" },
+    force ? "force" : undefined
+  );
+}
+
+function promiseProcessDied({ childID }) {
+  return new Promise(resolve => {
+    let observer = properties => {
+      properties.QueryInterface(Ci.nsIPropertyBag2);
+      let subjectChildID = properties.get("childID");
+      if (subjectChildID == childID) {
+        Services.obs.removeObserver(observer, "ipc:content-shutdown");
+        resolve();
+      }
+    };
+    Services.obs.addObserver(observer, "ipc:content-shutdown");
+  });
+}
+
+function isCloseEnough(value, expected) {
+  if (value < 0 || expected < 0) {
+    throw new Error(`Invalid isCloseEnough(${value}, ${expected})`);
+  }
+  if (Math.round(value) == Math.round(expected)) {
+    return true;
+  }
+  if (expected == 0) {
+    return false;
+  }
+  let ratio = value / expected;
+  if (ratio <= APPROX_FACTOR && ratio >= 1 / APPROX_FACTOR) {
+    return true;
+  }
+  return false;
+}
+
+function getMemoryMultiplier(unit, sign = "+") {
+  let multiplier;
+  switch (sign) {
+    case "+":
+      multiplier = 1;
+      break;
+    case "-":
+      multiplier = -1;
+      break;
+    default:
+      throw new Error("Invalid sign: " + sign);
+  }
+  switch (unit) {
+    case "B":
+      break;
+    case "KB":
+      multiplier *= 1024;
+      break;
+    case "MB":
+      multiplier *= 1024 * 1024;
+      break;
+    case "GB":
+      multiplier *= 1024 * 1024 * 1024;
+      break;
+    case "TB":
+      multiplier *= 1024 * 1024 * 1024 * 1024;
+      break;
+    default:
+      throw new Error("Invalid memory unit: " + unit);
+  }
+  return multiplier;
+}
+
+function getTimeMultiplier(unit) {
+  switch (unit) {
+    case "ns":
+      return 1 / (1000 * 1000);
+    case "µs":
+      return 1 / 1000;
+    case "ms":
+      return 1;
+    case "s":
+      return 1000;
+    case "m":
+      return 60000;
+  }
+  throw new Error("Invalid time unit: " + unit);
+}
+async function testCpu(element, total, slope, assumptions) {
+  info(
+    `Testing CPU display ${element.textContent} - ${element.title} vs total ${total}, slope ${slope}`
+  );
+  let barWidth = getComputedStyle(element).getPropertyValue("--bar-width");
+  if (slope) {
+    Assert.greater(
+      Number.parseFloat(barWidth),
+      0,
+      "The bar width should be > 0 when there is some CPU use"
+    );
+  } else {
+    Assert.equal(barWidth, "-0.5", "There should be no CPU bar displayed");
+  }
+
+  if (element.textContent == "(measuring)") {
+    info("Still measuring");
+    return;
+  }
+
+  const CPU_TEXT_CONTENT_REGEXP = /\~0%|idle|[0-9.,]+%|[?]/;
+  let extractedPercentage = CPU_TEXT_CONTENT_REGEXP.exec(
+    element.textContent
+  )[0];
+  switch (extractedPercentage) {
+    case "idle":
+      Assert.equal(slope, 0, "Idle means exactly 0%");
+      // Nothing else to do here.
+      return;
+    case "~0%":
+      Assert.ok(slope > 0 && slope < 0.0001);
+      break;
+    case "?":
+      Assert.ok(slope == null);
+      // Nothing else to do here.
+      return;
+    default: {
+      // `Number.parseFloat("99%")` returns `99`.
+      let computedPercentage = Number.parseFloat(extractedPercentage);
+      Assert.ok(
+        isCloseEnough(computedPercentage, slope * 100),
+        `The displayed approximation of the slope is reasonable: ${computedPercentage} vs ${
+          slope * 100
+        }`
+      );
+      // Also, sanity checks.
+      Assert.ok(
+        computedPercentage / 100 >= assumptions.minimalCPUPercentage,
+        `Not too little: ${computedPercentage / 100} >=? ${
+          assumptions.minimalCPUPercentage
+        } `
+      );
+      Assert.ok(
+        computedPercentage / 100 <= assumptions.maximalCPUPercentage,
+        `Not too much: ${computedPercentage / 100} <=? ${
+          assumptions.maximalCPUPercentage
+        } `
+      );
+      break;
+    }
+  }
+
+  const CPU_TOOLTIP_REGEXP = /(?:.*: ([0-9.,]+) ?(ns|µs|ms|s|m|h|d))/;
+  // Example: "Total CPU time: 4,470ms"
+
+  let [, extractedTotal, extractedUnit] = CPU_TOOLTIP_REGEXP.exec(
+    element.title
+  );
+
+  let totalMS = total / MS_PER_NS;
+  let computedTotal =
+    // We produce localized numbers, with "," as a thousands separator in en-US builds,
+    // but `parseFloat` doesn't understand the ",", so we need to remove it
+    // before parsing.
+    Number.parseFloat(extractedTotal.replace(/,/g, "")) *
+    getTimeMultiplier(extractedUnit);
+  Assert.ok(
+    isCloseEnough(computedTotal, totalMS),
+    `The displayed approximation of the total duration is reasonable: ${computedTotal} vs ${totalMS}`
+  );
+  Assert.ok(
+    totalMS <= assumptions.maximalCPUTotalDurationMS &&
+      totalMS >= assumptions.minimalCPUTotalDurationMS,
+    `The total number of MS is reasonable ${totalMS}: [${assumptions.minimalCPUTotalDurationMS}, ${assumptions.maximalCPUTotalDurationMS}]`
+  );
+}
+
+async function testMemory(element, total, delta, assumptions) {
+  info(
+    `Testing memory display ${element.textContent} - ${element.title} vs total ${total}, delta ${delta}`
+  );
+  const MEMORY_TEXT_CONTENT_REGEXP = /([0-9.,]+)(TB|GB|MB|KB|B)/;
+  // Example: "383.55MB"
+  let extracted = MEMORY_TEXT_CONTENT_REGEXP.exec(element.textContent);
+  Assert.notEqual(
+    extracted,
+    null,
+    `Can we parse ${element.textContent} with ${MEMORY_TEXT_CONTENT_REGEXP}?`
+  );
+  let [, extractedTotal, extractedUnit] = extracted;
+
+  let extractedTotalNumber = Number.parseFloat(extractedTotal);
+  Assert.ok(
+    extractedTotalNumber > 0,
+    `Unitless total memory use is greater than 0: ${extractedTotal}`
+  );
+  if (extractedUnit != "GB") {
+    Assert.ok(
+      extractedTotalNumber <= 1024,
+      `Unitless total memory use is less than 1024: ${extractedTotal}`
+    );
+  }
+
+  // Now check that the conversion was meaningful.
+  let computedTotal = getMemoryMultiplier(extractedUnit) * extractedTotalNumber;
+  Assert.ok(
+    isCloseEnough(computedTotal, total),
+    `The displayed approximation of the total amount of memory is reasonable: ${computedTotal} vs ${total}`
+  );
+  if (!AppConstants.ASAN) {
+    // ASAN plays tricks with RAM (e.g. allocates the entirety of virtual memory),
+    // which makes this test unrealistic.
+    Assert.ok(
+      assumptions.minimalRAMBytesUsage <= computedTotal &&
+        computedTotal <= assumptions.maximalRAMBytesUsage,
+      `The total amount amount of memory is reasonable: ${computedTotal} in [${assumptions.minimalRAMBytesUsage}, ${assumptions.maximalRAMBytesUsage}]`
+    );
+  }
+
+  const MEMORY_TOOLTIP_REGEXP = /(?:.*: ([-+]?)([0-9.,]+)(GB|MB|KB|B))?/;
+  // Example: "Evolution: -12.5MB"
+  extracted = MEMORY_TOOLTIP_REGEXP.exec(element.title);
+  Assert.notEqual(
+    extracted,
+    null,
+    `Can we parse ${element.title} with ${MEMORY_TOOLTIP_REGEXP}?`
+  );
+  let [, extractedDeltaSign, extractedDeltaTotal, extractedDeltaUnit] =
+    extracted;
+  if (extractedDeltaSign == null) {
+    Assert.equal(delta || 0, 0);
+    return;
+  }
+  let deltaTotalNumber = Number.parseFloat(
+    // Remove the thousands separator that breaks parseFloat.
+    extractedDeltaTotal.replace(/,/g, "")
+  );
+  // Note: displaying 1024KB can happen if the value is slightly less than
+  // 1024*1024B but rounded to 1024KB.
+  Assert.ok(
+    deltaTotalNumber > 0 && deltaTotalNumber <= 1024,
+    `Unitless delta memory use is in (0, 1024): ${extractedDeltaTotal}`
+  );
+  Assert.ok(
+    ["B", "KB", "MB"].includes(extractedDeltaUnit),
+    `Delta unit is reasonable: ${extractedDeltaUnit}`
+  );
+
+  // Now check that the conversion was meaningful.
+  // Let's just check that the number displayed is within 10% of `delta`.
+  let computedDelta =
+    getMemoryMultiplier(extractedDeltaUnit, extractedDeltaSign) *
+    deltaTotalNumber;
+  Assert.equal(
+    computedDelta >= 0,
+    delta >= 0,
+    `Delta has the right sign: ${computedDelta} vs ${delta}`
+  );
+}
+
+function extractProcessDetails(row) {
+  let children = row.children;
+  let name = children[0];
+  let memory = children[1];
+  let cpu = children[2];
+  if (Services.prefs.getBoolPref("toolkit.aboutProcesses.showProfilerIcons")) {
+    name = name.firstChild;
+    Assert.ok(
+      name.nextSibling.classList.contains("profiler-icon"),
+      "The profiler icon should be shown"
+    );
+  }
+  let fluentArgs = row.ownerDocument.l10n.getAttributes(name).args;
+  let threadDetailsRow = row.nextSibling;
+  while (threadDetailsRow) {
+    if (threadDetailsRow.classList.contains("process")) {
+      threadDetailsRow = null;
+      break;
+    }
+    if (threadDetailsRow.classList.contains("thread-summary")) {
+      break;
+    }
+    threadDetailsRow = threadDetailsRow.nextSibling;
+  }
+
+  return {
+    memory,
+    cpu,
+    pidContent: fluentArgs.pid,
+    threads: threadDetailsRow,
+  };
+}
+
+function findTabRowByName(doc, name) {
+  for (let row of doc.getElementsByClassName("name")) {
+    if (!row.parentNode.classList.contains("window")) {
+      continue;
+    }
+    let foundName = document.l10n.getAttributes(row).args.name;
+    if (foundName != name) {
+      continue;
+    }
+    return row.parentNode;
+  }
+  return null;
+}
+
+function findProcessRowByOrigin(doc, origin) {
+  for (let row of doc.getElementsByClassName("process")) {
+    if (row.process.origin == origin) {
+      return row;
+    }
+  }
+  return null;
+}
+
+async function setupTabWithOriginAndTitle(origin, title) {
+  let tab = BrowserTestUtils.addTab(gBrowser, origin, { skipAnimation: true });
+  tab.testTitle = title;
+  tab.testOrigin = origin;
+  await BrowserTestUtils.browserLoaded(tab.linkedBrowser);
+  await SpecialPowers.spawn(tab.linkedBrowser, [title], async title => {
+    content.document.title = title;
+  });
+  return tab;
+}
+
+async function setupAudioTab() {
+  let origin = "about:blank";
+  let title = "utility audio";
+  let tab = BrowserTestUtils.addTab(gBrowser, origin, { skipAnimation: true });
+  tab.testTitle = title;
+  tab.testOrigin = origin;
+  await BrowserTestUtils.browserLoaded(tab.linkedBrowser);
+  await SpecialPowers.spawn(tab.linkedBrowser, [title], async title => {
+    content.document.title = title;
+    const ROOT =
+      "https://example.com/browser/toolkit/components/aboutprocesses/tests/browser";
+    let audio = content.document.createElement("audio");
+    audio.setAttribute("controls", "true");
+    audio.setAttribute("loop", true);
+    audio.src = `${ROOT}/small-shot.mp3`;
+    content.document.body.appendChild(audio);
+    await audio.play();
+  });
+  return tab;
+}
+
+async function testAboutProcessesWithConfig({ showAllFrames, showThreads }) {
+  const isFission = gFissionBrowser;
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      ["toolkit.aboutProcesses.showAllSubframes", showAllFrames],
+      ["toolkit.aboutProcesses.showThreads", showThreads],
+      // Force same-origin tabs to share a single process, to properly test
+      // functionality involving multiple tabs within a single process with Fission.
+      ["dom.ipc.processCount.webIsolated", 1],
+      // Ensure utility audio decoder is enabled
+      ["media.utility-process.enabled", true],
+    ],
+  });
+
+  // Install a test extension to also cover processes and sub-frames related to the
+  // extension process.
+  const extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      browser_specific_settings: {
+        gecko: { id: "test-aboutprocesses@mochi.test" },
+      },
+    },
+    background() {
+      // Creates an about:blank iframe in the extension process to make sure that
+      // Bug 1665099 doesn't regress.
+      document.body.appendChild(document.createElement("iframe"));
+
+      this.browser.test.sendMessage("bg-page-loaded");
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("bg-page-loaded");
+
+  // Setup tabs asynchronously.
+
+  // The about:processes tab.
+  info("Setting up about:processes");
+  let promiseTabAboutProcesses = BrowserTestUtils.openNewForegroundTab({
+    gBrowser,
+    opening: "about:processes",
+    waitForLoad: true,
+  });
+
+  info("Setting up example.com");
+  // Another tab that we'll pretend is hung.
+  let promiseTabHung = (async function () {
+    let tab = BrowserTestUtils.addTab(gBrowser, "http://example.com", {
+      skipAnimation: true,
+    });
+    await BrowserTestUtils.browserLoaded(tab.linkedBrowser);
+    let p = BrowserTestUtils.browserLoaded(
+      tab.linkedBrowser,
+      true /* includeSubFrames */
+    );
+    await SpecialPowers.spawn(tab.linkedBrowser, [], async () => {
+      // Open an in-process iframe to test toolkit.aboutProcesses.showAllSubframes
+      let frame = content.document.createElement("iframe");
+      content.document.body.appendChild(frame);
+    });
+    await p;
+    return tab;
+  })();
+
+  let promiseAudioPlayback = setupAudioTab();
+
+  let promiseUserContextTab = (async function () {
+    let tab = BrowserTestUtils.addTab(gBrowser, "http://example.com", {
+      userContextId: 1,
+      skipAnimation: true,
+    });
+    await BrowserTestUtils.browserLoaded(tab.linkedBrowser);
+    await SpecialPowers.spawn(tab.linkedBrowser, [], () => {
+      content.document.title = "Tab with User Context";
+    });
+    return tab;
+  })();
+
+  info("Setting up tabs we intend to close");
+
+  // The two following tabs share the same domain.
+  // We use them to check that closing one doesn't close the other.
+  let promiseTabCloseSeparately1 = setupTabWithOriginAndTitle(
+    "http://example.org",
+    "Close me 1 (separately)"
+  );
+  let promiseTabCloseSeparately2 = setupTabWithOriginAndTitle(
+    "http://example.org",
+    "Close me 2 (separately)"
+  );
+
+  // The two following tabs share the same domain.
+  // We use them to check that closing the process kills them both.
+  let promiseTabCloseProcess1 = setupTabWithOriginAndTitle(
+    "http://example.net",
+    "Close me 1 (process)"
+  );
+
+  let promiseTabCloseProcess2 = setupTabWithOriginAndTitle(
+    "http://example.net",
+    "Close me 2 (process)"
+  );
+
+  // The two following tabs share the same domain.
+  // We use them to check that closing the process kills them both.
+  let promiseTabCloseTogether1 = setupTabWithOriginAndTitle(
+    "https://example.org",
+    "Close me 1 (together)"
+  );
+
+  let promiseTabCloseTogether2 = setupTabWithOriginAndTitle(
+    "https://example.org",
+    "Close me 2 (together)"
+  );
+
+  // Wait for initialization to finish.
+  let tabAboutProcesses = await promiseTabAboutProcesses;
+  let tabHung = await promiseTabHung;
+  let audioPlayback = await promiseAudioPlayback;
+  let tabUserContext = await promiseUserContextTab;
+  let tabCloseSeparately1 = await promiseTabCloseSeparately1;
+  let tabCloseSeparately2 = await promiseTabCloseSeparately2;
+  let tabCloseProcess1 = await promiseTabCloseProcess1;
+  let tabCloseProcess2 = await promiseTabCloseProcess2;
+  let tabCloseTogether1 = await promiseTabCloseTogether1;
+  let tabCloseTogether2 = await promiseTabCloseTogether2;
+
+  let doc = tabAboutProcesses.linkedBrowser.contentDocument;
+  let tbody = doc.getElementById("process-tbody");
+  Assert.ok(!!tbody, "Found the #process-tbody element");
+
+  if (isFission) {
+    // We're going to kill this process later, so tell it to add an
+    // annotation so the leak checker knows it is okay there is no
+    // leak log.
+    await SpecialPowers.spawn(tabCloseProcess1.linkedBrowser, [], () => {
+      ChromeUtils.privateNoteIntentionalCrash();
+    });
+  }
+
+  info("Setting up fake process hang detector");
+  let hungChildID = tabHung.linkedBrowser.frameLoader.childID;
+
+  // Keep informing about:processes that `tabHung` is hung.
+  // Note: this is a background task, do not `await` it.
+  let fakeProcessHangMonitor = async function () {
+    for (let i = 0; i < 100; ++i) {
+      if (!tabHung.linkedBrowser) {
+        // Let's stop spamming as soon as we can.
+        return;
+      }
+
+      Services.obs.notifyObservers(
+        {
+          childID: hungChildID,
+          scriptBrowser: tabHung.linkedBrowser,
+          scriptFileName: "chrome://browser/content/browser.js",
+          QueryInterface: ChromeUtils.generateQI(["nsIHangReport"]),
+        },
+        "process-hang-report"
+      );
+
+      // eslint-disable-next-line mozilla/no-arbitrary-setTimeout
+      await new Promise(resolve => setTimeout(resolve, 300));
+    }
+  };
+  fakeProcessHangMonitor();
+
+  // about:processes will take a little time to appear and be populated.
+  await promiseAboutProcessesUpdated({ doc, tabAboutProcesses });
+  Assert.ok(tbody.childElementCount, "The table should be populated");
+  Assert.ok(
+    !!tbody.getElementsByClassName("hung").length,
+    "The hung process should appear"
+  );
+
+  info("Looking at the contents of about:processes");
+  let processesToBeFound = [
+    // The browser process.
+    {
+      name: "browser",
+      predicate: row => row.process.type == "browser",
+    },
+    // The hung process.
+    {
+      name: "hung",
+      predicate: row =>
+        row.classList.contains("hung") &&
+        row.classList.contains("process") &&
+        ["web", "webIsolated"].includes(row.process.type),
+    },
+    // Any non-hung process
+    {
+      name: "non-hung",
+      predicate: row =>
+        !row.classList.contains("hung") &&
+        row.classList.contains("process") &&
+        ["web", "webIsolated"].includes(row.process.type),
+    },
+    // A utility process with at least one actor.
+    {
+      name: "utility",
+      predicate: row =>
+        row.process &&
+        row.process.type == "utility" &&
+        row.classList.contains("process") &&
+        row.nextSibling &&
+        row.nextSibling.classList.contains("actor"),
+    },
+  ];
+  for (let finder of processesToBeFound) {
+    info(`Running sanity tests on ${finder.name}`);
+    let row = tbody.firstChild;
+    while (row) {
+      if (finder.predicate(row)) {
+        break;
+      }
+      row = row.nextSibling;
+    }
+    Assert.ok(!!row, `found a table row for ${finder.name}`);
+    let { memory, cpu, pidContent, threads } = extractProcessDetails(row);
+
+    info("Sanity checks: pid");
+    let pid = Number.parseInt(pidContent);
+    Assert.ok(pid > 0, `Checking pid ${pidContent}`);
+    Assert.equal(pid, row.process.pid);
+
+    info("Sanity checks: memory resident");
+    await testMemory(
+      memory,
+      row.process.totalRamSize,
+      row.process.deltaRamSize,
+      HARDCODED_ASSUMPTIONS_PROCESS
+    );
+
+    info("Sanity checks: CPU (Total)");
+    await testCpu(
+      cpu,
+      row.process.totalCpu,
+      row.process.slopeCpu,
+      HARDCODED_ASSUMPTIONS_PROCESS
+    );
+
+    // Testing threads.
+    if (!showThreads) {
+      info("In this mode, we shouldn't display any threads");
+      Assert.equal(
+        threads,
+        null,
+        "In hidden threads mode, we shouldn't have any thread summary"
+      );
+    } else {
+      Assert.ok(threads, "We have a thread summary row");
+
+      let {
+        number,
+        active = 0,
+        list,
+      } = doc.l10n.getAttributes(threads.children[0].children[1]).args;
+
+      info("Sanity checks: number of threads");
+      Assert.greaterOrEqual(
+        number,
+        HARDCODED_ASSUMPTIONS_PROCESS.minimalNumberOfThreads
+      );
+      Assert.lessOrEqual(
+        number,
+        HARDCODED_ASSUMPTIONS_PROCESS.maximalNumberOfThreads
+      );
+      Assert.equal(
+        number,
+        row.process.threads.length,
+        "The number we display should be the number of threads"
+      );
+
+      info("Sanity checks: number of active threads");
+      Assert.greaterOrEqual(
+        active,
+        0,
+        "The number of active threads should never be negative"
+      );
+      Assert.lessOrEqual(
+        active,
+        number,
+        "The number of active threads should not exceed the total number of threads"
+      );
+      let activeThreads = row.process.threads.filter(t => t.active);
+      Assert.equal(
+        active,
+        activeThreads.length,
+        "The displayed number of active threads should be correct"
+      );
+
+      let activeSet = new Set();
+      for (let t of activeThreads) {
+        activeSet.add(t.name.replace(/ ?#[0-9]+$/, ""));
+      }
+      info("Sanity checks: thread list");
+      Assert.equal(
+        list ? list.split(", ").length : 0,
+        activeSet.size,
+        "The thread summary list of active threads should have the expected length"
+      );
+
+      info("Testing that we can open the list of threads");
+      let twisty = threads.getElementsByClassName("twisty")[0];
+      twisty.click();
+
+      // Fluent will update the text content of new rows during the
+      // next refresh driver tick, wait for it.
+      // requestAnimationFrame calls us at the begining of the tick, we use
+      // dispatchToMainThread to execute our code after the end of it.
+      //XXX: Replace with proper wait for l10n completion once bug 1520659 is fixed.
+      await new Promise(doc.defaultView.requestAnimationFrame);
+      await new Promise(resolve => Services.tm.dispatchToMainThread(resolve));
+
+      let numberOfThreadsFound = 0;
+      for (
+        let threadRow = threads.nextSibling;
+        threadRow && threadRow.classList.contains("thread");
+        threadRow = threadRow.nextSibling
+      ) {
+        numberOfThreadsFound++;
+      }
+      Assert.equal(
+        numberOfThreadsFound,
+        number,
+        `We should see ${number} threads, found ${numberOfThreadsFound}`
+      );
+      let threadIds = [];
+      for (
+        let threadRow = threads.nextSibling;
+        threadRow && threadRow.classList.contains("thread");
+        threadRow = threadRow.nextSibling
+      ) {
+        Assert.ok(
+          threadRow.children.length >= 3 && threadRow.children[1].textContent,
+          "The thread row should be populated"
+        );
+        let children = threadRow.children;
+        let cpu = children[1];
+        let l10nArgs = doc.l10n.getAttributes(children[0]).args;
+
+        // Sanity checks: name
+        Assert.ok(threadRow.thread.name, "Thread name is not empty");
+        Assert.equal(
+          l10nArgs.name,
+          threadRow.thread.name,
+          "Displayed thread name is correct"
+        );
+
+        // Sanity checks: tid
+        let tidContent = l10nArgs.tid;
+        let tid = Number.parseInt(tidContent);
+        threadIds.push(tid);
+        Assert.notEqual(tid, 0, "The tid should be set");
+        Assert.equal(tid, threadRow.thread.tid, "Displayed tid is correct");
+
+        // Sanity checks: CPU (per thread)
+        await testCpu(
+          cpu,
+          threadRow.thread.totalCpu,
+          threadRow.thread.slopeCpu,
+          HARDCODED_ASSUMPTIONS_THREAD
+        );
+      }
+      // By default, threads are sorted by tid.
+      let threadList = threadIds.join(",");
+      Assert.equal(
+        threadList,
+        threadIds.sort((a, b) => a - b).join(","),
+        "The thread rows are in the default sort order."
+      );
+    }
+  }
+
+  await promiseAboutProcessesUpdated({
+    doc,
+    force: true,
+    tabAboutProcesses,
+  });
+
+  // Testing subframes.
+  info("Testing subframes");
+  let foundAtLeastOneInProcessSubframe = false;
+  for (let row of doc.getElementsByClassName("window")) {
+    let subframe = row.win;
+    if (subframe.tab) {
+      continue;
+    }
+    let url = doc.l10n.getAttributes(row.children[0]).args.url;
+    Assert.equal(url, subframe.documentURI.spec);
+    if (!subframe.isProcessRoot) {
+      foundAtLeastOneInProcessSubframe = true;
+    }
+  }
+  if (showAllFrames) {
+    Assert.ok(
+      foundAtLeastOneInProcessSubframe,
+      "Found at least one about:blank in-process subframe"
+    );
+  } else {
+    Assert.ok(
+      !foundAtLeastOneInProcessSubframe,
+      "We shouldn't have any about:blank in-process subframe"
+    );
+  }
+
+  info("Double-clicking on a tab");
+  let whenTabSwitchedToWeb = BrowserTestUtils.switchTab(gBrowser, () => {
+    // We pass a function to use `BrowserTestUtils.switchTab` not in its
+    // role as a tab switcher but rather in its role as a function that
+    // waits until something else has switched the tab.
+    // We'll actually cause tab switching below, by doucle-clicking
+    // in `about:processes`.
+  });
+  await SpecialPowers.spawn(tabAboutProcesses.linkedBrowser, [], async () => {
+    // Locate and double-click on the representation of `tabHung`.
+    let tbody = content.document.getElementById("process-tbody");
+    for (let row of tbody.getElementsByClassName("tab")) {
+      if (row.parentNode.win.documentURI.spec != "http://example.com/") {
+        continue;
+      }
+      // Simulate double-click.
+      let evt = new content.window.MouseEvent("dblclick", {
+        bubbles: true,
+        cancelable: true,
+        view: content.window,
+      });
+      row.dispatchEvent(evt);
+      return;
+    }
+    Assert.ok(false, "We should have found the hung tab");
+  });
+
+  info("Waiting for tab switch");
+  await whenTabSwitchedToWeb;
+  Assert.equal(
+    gBrowser.selectedTab.linkedBrowser.currentURI.spec,
+    tabHung.linkedBrowser.currentURI.spec,
+    "We should have focused the hung tab"
+  );
+
+  await BrowserTestUtils.switchTab(gBrowser, tabAboutProcesses);
+
+  info("Double-clicking on the extensions process");
+  let tabPromise = BrowserTestUtils.waitForNewTab(gBrowser, "about:addons");
+  await SpecialPowers.spawn(tabAboutProcesses.linkedBrowser, [], async () => {
+    let extensionsRow =
+      content.document.getElementsByClassName("extensions")[0];
+    Assert.ok(!!extensionsRow, "We should have found the extensions process");
+    let evt = new content.window.MouseEvent("dblclick", {
+      bubbles: true,
+      cancelable: true,
+      view: content.window,
+    });
+    extensionsRow.dispatchEvent(evt);
+  });
+  info("Waiting for about:addons to open");
+  await tabPromise;
+  Assert.equal(
+    gBrowser.selectedTab.linkedBrowser.currentURI.spec,
+    "about:addons",
+    "We should now see the addon tab"
+  );
+  BrowserTestUtils.removeTab(gBrowser.selectedTab);
+
+  info("Testing tab closing");
+
+  // A list of processes we have killed and for which we're waiting
+  // death confirmation. Only used in Fission.
+  let waitForProcessesToDisappear = [];
+  await promiseAboutProcessesUpdated({
+    doc,
+    force: true,
+    tabAboutProcesses,
+  });
+  if (isFission) {
+    // Before closing, all our origins should be present
+    for (let origin of [
+      "http://example.com", // tabHung
+      "http://example.net", // tabCloseProcess*
+      "http://example.org", // tabCloseSeparately*
+      "https://example.org", // tabCloseTogether*
+    ]) {
+      Assert.ok(
+        findProcessRowByOrigin(doc, origin),
+        `There is a process for origin ${origin}`
+      );
+    }
+
+    // Verify that the user context id has been correctly displayed.
+    let userContextProcessRow = findProcessRowByOrigin(
+      doc,
+      "http://example.com^userContextId=1"
+    );
+    Assert.ok(
+      userContextProcessRow,
+      "There is a separate process for the tab with a different user context"
+    );
+    let name = userContextProcessRow.firstChild;
+    if (
+      Services.prefs.getBoolPref("toolkit.aboutProcesses.showProfilerIcons")
+    ) {
+      name = name.firstChild;
+      Assert.ok(
+        name.nextSibling.classList.contains("profiler-icon"),
+        "The profiler icon should be shown"
+      );
+    }
+    Assert.equal(
+      doc.l10n.getAttributes(name).args.origin,
+      "http://example.com — " +
+        ContextualIdentityService.getUserContextLabel(1),
+      "The user context ID should be replaced with the localized container name"
+    );
+
+    // These origins will disappear.
+    for (let origin of [
+      "http://example.net", // tabCloseProcess*
+      "https://example.org", // tabCloseTogether*
+    ]) {
+      let row = findProcessRowByOrigin(doc, origin);
+      let childID = row.process.childID;
+      waitForProcessesToDisappear.push(promiseProcessDied({ childID }));
+    }
+  }
+
+  // Close a few tabs.
+  for (let tab of [tabCloseSeparately1, tabCloseTogether1, tabCloseTogether2]) {
+    info("Closing a tab through about:processes");
+    let found = findTabRowByName(doc, tab.linkedBrowser.contentTitle);
+    Assert.ok(
+      found,
+      `We should have found tab ${tab.linkedBrowser.contentTitle} to close it`
+    );
+    let closeIcons = found.getElementsByClassName("close-icon");
+    Assert.equal(
+      closeIcons.length,
+      1,
+      "This tab should have exactly one close icon"
+    );
+    closeIcons[0].click();
+    Assert.ok(
+      found.classList.contains("killing"),
+      "We should have marked the row as dying"
+    );
+  }
+
+  //...and a process, if we're in Fission.
+  if (isFission) {
+    info("Closing an entire process through about:processes");
+    let found = findProcessRowByOrigin(doc, "http://example.net");
+    let closeIcons = found.getElementsByClassName("close-icon");
+    Assert.equal(
+      closeIcons.length,
+      1,
+      "This process should have exactly one close icon"
+    );
+    closeIcons[0].click();
+    Assert.ok(
+      found.classList.contains("killing"),
+      "We should have marked the row as dying"
+    );
+  }
+
+  // Give Firefox a little time to close the tabs and update about:processes.
+  // This might take two updates as we're racing between collecting data and
+  // processes actually being killed.
+  await promiseAboutProcessesUpdated({
+    doc,
+    force: true,
+    tabAboutProcesses,
+  });
+
+  // The tabs we have closed directly or indirectly should now be (closed or crashed) and invisible in about:processes.
+  for (let { origin, tab } of [
+    { origin: "http://example.org", tab: tabCloseSeparately1 },
+    { origin: "https://example.org", tab: tabCloseTogether1 },
+    { origin: "https://example.org", tab: tabCloseTogether2 },
+    ...(isFission
+      ? [
+          { origin: "http://example.net", tab: tabCloseProcess1 },
+          { origin: "http://example.net", tab: tabCloseProcess2 },
+        ]
+      : []),
+  ]) {
+    // Tab shouldn't show up anymore in about:processes
+    Assert.ok(
+      !findTabRowByName(doc, origin),
+      `Tab for ${origin} shouldn't show up anymore in about:processes`
+    );
+    // ...and should be unloaded.
+    Assert.ok(
+      !tab.getAttribute("linkedPanel"),
+      `The tab should now be unloaded (${tab.testOrigin} - ${tab.testTitle})`
+    );
+  }
+
+  // On the other hand, tabs we haven't closed should still be open and visible in about:processes.
+  Assert.ok(
+    tabCloseSeparately2.linkedBrowser,
+    "Killing one tab in the domain should not have closed the other tab"
+  );
+  let foundtabCloseSeparately2 = findTabRowByName(
+    doc,
+    tabCloseSeparately2.linkedBrowser.contentTitle
+  );
+  Assert.ok(
+    foundtabCloseSeparately2,
+    "The second tab is still visible in about:processes"
+  );
+
+  if (isFission) {
+    // After closing, we must have closed some of our origins.
+    for (let origin of [
+      "http://example.com", // tabHung
+      "http://example.org", // tabCloseSeparately*
+    ]) {
+      Assert.ok(
+        findProcessRowByOrigin(doc, origin),
+        `There should still be a process row for origin ${origin}`
+      );
+    }
+
+    info("Waiting for processes to die");
+    await Promise.all(waitForProcessesToDisappear);
+
+    info("Waiting for about:processes to be updated");
+    await promiseAboutProcessesUpdated({
+      doc,
+      force: true,
+      tabAboutProcesses,
+    });
+
+    for (let origin of [
+      "http://example.net", // tabCloseProcess*
+      "https://example.org", // tabCloseTogether*
+    ]) {
+      Assert.ok(
+        !findProcessRowByOrigin(doc, origin),
+        `Process ${origin} should disappear from about:processes`
+      );
+    }
+  }
+
+  info("Additional sanity check for all processes");
+  for (let row of doc.getElementsByClassName("process")) {
+    let { pidContent } = extractProcessDetails(row);
+    Assert.equal(Number.parseInt(pidContent), row.process.pid);
+  }
+  BrowserTestUtils.removeTab(tabAboutProcesses);
+  BrowserTestUtils.removeTab(tabHung);
+  BrowserTestUtils.removeTab(tabUserContext);
+  BrowserTestUtils.removeTab(tabCloseSeparately2);
+
+  // We still need to remove these tabs.
+  // We killed the process, but we don't want to leave zombie tabs lying around.
+  BrowserTestUtils.removeTab(tabCloseProcess1);
+  BrowserTestUtils.removeTab(tabCloseProcess2);
+  BrowserTestUtils.removeTab(audioPlayback);
+
+  await SpecialPowers.popPrefEnv();
+
+  await extension.unload();
+}
diff --git a/toolkit/components/aboutprocesses/tests/browser/small-shot.mp3 b/toolkit/components/aboutprocesses/tests/browser/small-shot.mp3
new file mode 100644
index 0000000000..f9397a5106
--- /dev/null
+++ b/toolkit/components/aboutprocesses/tests/browser/small-shot.mp3