Adding upstream version 115.7.0esr.upstream/115.7.0esr

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

115 files changed, 14772 insertions, 0 deletions

diff --git a/toolkit/components/pictureinpicture/PictureInPicture.sys.mjs b/toolkit/components/pictureinpicture/PictureInPicture.sys.mjs
new file mode 100644
index 0000000000..8916d92313
--- /dev/null
+++ b/toolkit/components/pictureinpicture/PictureInPicture.sys.mjs
@@ -0,0 +1,1603 @@
+/* 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/. */
+
+import { AppConstants } from "resource://gre/modules/AppConstants.sys.mjs";
+
+import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
+
+import { ShortcutUtils } from "resource://gre/modules/ShortcutUtils.sys.mjs";
+
+const lazy = {};
+XPCOMUtils.defineLazyServiceGetters(lazy, {
+  WindowsUIUtils: ["@mozilla.org/windows-ui-utils;1", "nsIWindowsUIUtils"],
+});
+
+ChromeUtils.defineESModuleGetters(lazy, {
+  PrivateBrowsingUtils: "resource://gre/modules/PrivateBrowsingUtils.sys.mjs",
+});
+
+import { Rect, Point } from "resource://gre/modules/Geometry.sys.mjs";
+
+const PLAYER_URI = "chrome://global/content/pictureinpicture/player.xhtml";
+// Currently, we need titlebar="yes" on macOS in order for the player window
+// to be resizable. See bug 1824171.
+const TITLEBAR = AppConstants.platform == "macosx" ? "yes" : "no";
+const PLAYER_FEATURES = `chrome,alwaysontop,lockaspectratio,resizable,dialog,titlebar=${TITLEBAR}`;
+
+const WINDOW_TYPE = "Toolkit:PictureInPicture";
+const TOGGLE_ENABLED_PREF =
+  "media.videocontrols.picture-in-picture.video-toggle.enabled";
+const TOGGLE_FIRST_SEEN_PREF =
+  "media.videocontrols.picture-in-picture.video-toggle.first-seen-secs";
+const TOGGLE_HAS_USED_PREF =
+  "media.videocontrols.picture-in-picture.video-toggle.has-used";
+const TOGGLE_POSITION_PREF =
+  "media.videocontrols.picture-in-picture.video-toggle.position";
+const TOGGLE_POSITION_RIGHT = "right";
+const TOGGLE_POSITION_LEFT = "left";
+const RESIZE_MARGIN_PX = 16;
+const BACKGROUND_DURATION_HISTOGRAM_ID =
+  "FX_PICTURE_IN_PICTURE_BACKGROUND_TAB_PLAYING_DURATION";
+const FOREGROUND_DURATION_HISTOGRAM_ID =
+  "FX_PICTURE_IN_PICTURE_FOREGROUND_TAB_PLAYING_DURATION";
+
+XPCOMUtils.defineLazyPreferenceGetter(
+  lazy,
+  "PIP_ENABLED",
+  "media.videocontrols.picture-in-picture.enabled",
+  false
+);
+XPCOMUtils.defineLazyPreferenceGetter(
+  lazy,
+  "PIP_URLBAR_BUTTON",
+  "media.videocontrols.picture-in-picture.urlbar-button.enabled",
+  false
+);
+XPCOMUtils.defineLazyPreferenceGetter(
+  lazy,
+  "RESPECT_PIP_DISABLED",
+  "media.videocontrols.picture-in-picture.respect-disablePictureInPicture",
+  true
+);
+
+/**
+ * Tracks the number of currently open player windows for Telemetry tracking
+ */
+let gCurrentPlayerCount = 0;
+
+/**
+ * To differentiate windows in the Telemetry Event Log, each Picture-in-Picture
+ * player window is given a unique ID.
+ */
+let gNextWindowID = 0;
+
+export class PictureInPictureLauncherParent extends JSWindowActorParent {
+  receiveMessage(aMessage) {
+    switch (aMessage.name) {
+      case "PictureInPicture:Request": {
+        let videoData = aMessage.data;
+        PictureInPicture.handlePictureInPictureRequest(this.manager, videoData);
+        break;
+      }
+    }
+  }
+}
+
+export class PictureInPictureToggleParent extends JSWindowActorParent {
+  receiveMessage(aMessage) {
+    let browsingContext = aMessage.target.browsingContext;
+    let browser = browsingContext.top.embedderElement;
+    switch (aMessage.name) {
+      case "PictureInPicture:OpenToggleContextMenu": {
+        let win = browser.ownerGlobal;
+        PictureInPicture.openToggleContextMenu(win, aMessage.data);
+        break;
+      }
+      case "PictureInPicture:UpdateEligiblePipVideoCount": {
+        let { pipCount, pipDisabledCount } = aMessage.data;
+        PictureInPicture.updateEligiblePipVideoCount(browsingContext, {
+          pipCount,
+          pipDisabledCount,
+        });
+        PictureInPicture.updateUrlbarToggle(browser);
+        break;
+      }
+      case "PictureInPicture:SetFirstSeen": {
+        let { dateSeconds } = aMessage.data;
+        PictureInPicture.setFirstSeen(dateSeconds);
+        break;
+      }
+      case "PictureInPicture:SetHasUsed": {
+        let { hasUsed } = aMessage.data;
+        PictureInPicture.setHasUsed(hasUsed);
+        break;
+      }
+    }
+  }
+}
+
+/**
+ * This module is responsible for creating a Picture in Picture window to host
+ * a clone of a video element running in web content.
+ */
+export class PictureInPictureParent extends JSWindowActorParent {
+  receiveMessage(aMessage) {
+    switch (aMessage.name) {
+      case "PictureInPicture:Resize": {
+        let videoData = aMessage.data;
+        PictureInPicture.resizePictureInPictureWindow(videoData, this);
+        break;
+      }
+      case "PictureInPicture:Close": {
+        /**
+         * Content has requested that its Picture in Picture window go away.
+         */
+        let reason = aMessage.data.reason;
+        PictureInPicture.closeSinglePipWindow({ reason, actorRef: this });
+        break;
+      }
+      case "PictureInPicture:Playing": {
+        let player = PictureInPicture.getWeakPipPlayer(this);
+        if (player) {
+          player.setIsPlayingState(true);
+        }
+        break;
+      }
+      case "PictureInPicture:Paused": {
+        let player = PictureInPicture.getWeakPipPlayer(this);
+        if (player) {
+          player.setIsPlayingState(false);
+        }
+        break;
+      }
+      case "PictureInPicture:Muting": {
+        let player = PictureInPicture.getWeakPipPlayer(this);
+        if (player) {
+          player.setIsMutedState(true);
+        }
+        break;
+      }
+      case "PictureInPicture:Unmuting": {
+        let player = PictureInPicture.getWeakPipPlayer(this);
+        if (player) {
+          player.setIsMutedState(false);
+        }
+        break;
+      }
+      case "PictureInPicture:EnableSubtitlesButton": {
+        let player = PictureInPicture.getWeakPipPlayer(this);
+        if (player) {
+          player.enableSubtitlesButton();
+        }
+        break;
+      }
+      case "PictureInPicture:DisableSubtitlesButton": {
+        let player = PictureInPicture.getWeakPipPlayer(this);
+        if (player) {
+          player.disableSubtitlesButton();
+        }
+        break;
+      }
+      case "PictureInPicture:SetTimestampAndScrubberPosition": {
+        let { timestamp, scrubberPosition } = aMessage.data;
+        let player = PictureInPicture.getWeakPipPlayer(this);
+        player.setTimestamp(timestamp);
+        player.setScrubberPosition(scrubberPosition);
+        break;
+      }
+    }
+  }
+}
+
+/**
+ * This module is responsible for creating a Picture in Picture window to host
+ * a clone of a video element running in web content.
+ */
+export var PictureInPicture = {
+  // Maps PictureInPictureParent actors to their corresponding PiP player windows
+  weakPipToWin: new WeakMap(),
+
+  // Maps PiP player windows to their originating content's browser
+  weakWinToBrowser: new WeakMap(),
+
+  // Maps a browser to the number of PiP windows it has
+  browserWeakMap: new WeakMap(),
+
+  // Maps an AppWindow to the number of PiP windows it has
+  originatingWinWeakMap: new WeakMap(),
+
+  // Maps a WindowGlobal to count of eligible PiP videos
+  weakGlobalToEligiblePipCount: new WeakMap(),
+
+  /**
+   * Returns the player window if one exists and if it hasn't yet been closed.
+   *
+   * @param {PictureInPictureParent} pipActorRef
+   *   Reference to the calling PictureInPictureParent actor
+   *
+   * @returns {Window} the player window if it exists and is not in the
+   * process of being closed. Returns null otherwise.
+   */
+  getWeakPipPlayer(pipActorRef) {
+    let playerWin = this.weakPipToWin.get(pipActorRef);
+    if (!playerWin || playerWin.closed) {
+      return null;
+    }
+    return playerWin;
+  },
+
+  /**
+   * Get the PiP panel for a browser. Create the panel if needed.
+   * @param {Browser} browser The current browser
+   * @returns panel The panel element
+   */
+  getPanelForBrowser(browser) {
+    let panel = browser.ownerDocument.querySelector("#PictureInPicturePanel");
+
+    if (!panel) {
+      browser.ownerGlobal.ensureCustomElements("moz-toggle");
+      browser.ownerGlobal.ensureCustomElements("moz-support-link");
+      let template = browser.ownerDocument.querySelector(
+        "#PictureInPicturePanelTemplate"
+      );
+      let clone = template.content.cloneNode(true);
+      template.replaceWith(clone);
+
+      panel = this.getPanelForBrowser(browser);
+    }
+    return panel;
+  },
+
+  handleEvent(event) {
+    switch (event.type) {
+      case "TabSwapPictureInPicture": {
+        this.onPipSwappedBrowsers(event);
+        break;
+      }
+      case "TabSelect": {
+        this.updatePlayingDurationHistograms();
+        break;
+      }
+    }
+  },
+
+  /**
+   * Increase the count of PiP windows for a given browser
+   * @param browser The browser to increase PiP count in browserWeakMap
+   */
+  addPiPBrowserToWeakMap(browser) {
+    let count = this.browserWeakMap.has(browser)
+      ? this.browserWeakMap.get(browser)
+      : 0;
+    this.browserWeakMap.set(browser, count + 1);
+
+    // If a browser is being added to the browserWeakMap, that means its
+    // probably a good time to make sure the playing duration histograms
+    // are up-to-date, as it means that we've either opened a new PiP
+    // player window, or moved the originating tab to another window.
+    this.updatePlayingDurationHistograms();
+  },
+
+  /**
+   * Increase the count of PiP windows for a given AppWindow.
+   *
+   * @param {Browser} browser
+   *   The content browser that the originating video lives in and from which
+   *   we'll read its parent window to increase PiP window count in originatingWinWeakMap.
+   */
+  addOriginatingWinToWeakMap(browser) {
+    let parentWin = browser.ownerGlobal;
+    let count = this.originatingWinWeakMap.get(parentWin);
+    if (!count || count == 0) {
+      this.setOriginatingWindowActive(parentWin.browsingContext, true);
+      this.originatingWinWeakMap.set(parentWin, 1);
+
+      let gBrowser = browser.getTabBrowser();
+      if (gBrowser) {
+        gBrowser.tabContainer.addEventListener("TabSelect", this);
+      }
+    } else {
+      this.originatingWinWeakMap.set(parentWin, count + 1);
+    }
+  },
+
+  /**
+   * Decrease the count of PiP windows for a given browser.
+   * If the count becomes 0, we will remove the browser from the WeakMap
+   * @param browser The browser to decrease PiP count in browserWeakMap
+   */
+  removePiPBrowserFromWeakMap(browser) {
+    let count = this.browserWeakMap.get(browser);
+    if (count <= 1) {
+      this.browserWeakMap.delete(browser);
+      let tabbrowser = browser.getTabBrowser();
+      if (tabbrowser && !tabbrowser.shouldActivateDocShell(browser)) {
+        browser.docShellIsActive = false;
+      }
+    } else {
+      this.browserWeakMap.set(browser, count - 1);
+    }
+  },
+
+  /**
+   * Decrease the count of PiP windows for a given AppWindow.
+   * If the count becomes 0, we will remove the AppWindow from the WeakMap.
+   *
+   * @param {Browser} browser
+   *   The content browser that the originating video lives in and from which
+   *   we'll read its parent window to decrease PiP window count in originatingWinWeakMap.
+   */
+  removeOriginatingWinFromWeakMap(browser) {
+    let parentWin = browser?.ownerGlobal;
+
+    if (!parentWin) {
+      return;
+    }
+
+    let count = this.originatingWinWeakMap.get(parentWin);
+    if (!count || count <= 1) {
+      this.originatingWinWeakMap.delete(parentWin, 0);
+      this.setOriginatingWindowActive(parentWin.browsingContext, false);
+
+      let gBrowser = browser.getTabBrowser();
+      if (gBrowser) {
+        gBrowser.tabContainer.removeEventListener("TabSelect", this);
+      }
+    } else {
+      this.originatingWinWeakMap.set(parentWin, count - 1);
+    }
+  },
+
+  onPipSwappedBrowsers(event) {
+    let otherTab = event.detail;
+    if (otherTab) {
+      for (let win of Services.wm.getEnumerator(WINDOW_TYPE)) {
+        if (this.weakWinToBrowser.get(win) === event.target.linkedBrowser) {
+          this.weakWinToBrowser.set(win, otherTab.linkedBrowser);
+          this.removePiPBrowserFromWeakMap(event.target.linkedBrowser);
+          this.removeOriginatingWinFromWeakMap(event.target.linkedBrowser);
+          this.addPiPBrowserToWeakMap(otherTab.linkedBrowser);
+          this.addOriginatingWinToWeakMap(otherTab.linkedBrowser);
+        }
+      }
+      otherTab.addEventListener("TabSwapPictureInPicture", this);
+    }
+  },
+
+  updatePlayingDurationHistograms() {
+    // A tab switch occurred in a browser window with one more tabs that have
+    // PiP player windows associated with them.
+    for (let win of Services.wm.getEnumerator(WINDOW_TYPE)) {
+      let browser = this.weakWinToBrowser.get(win);
+      let gBrowser = browser.getTabBrowser();
+      if (gBrowser?.selectedBrowser == browser) {
+        // If there are any background stopwatches running for this window, finish
+        // them and switch to foreground.
+        if (TelemetryStopwatch.running(BACKGROUND_DURATION_HISTOGRAM_ID, win)) {
+          TelemetryStopwatch.finish(BACKGROUND_DURATION_HISTOGRAM_ID, win);
+        }
+        if (
+          !TelemetryStopwatch.running(FOREGROUND_DURATION_HISTOGRAM_ID, win)
+        ) {
+          TelemetryStopwatch.start(FOREGROUND_DURATION_HISTOGRAM_ID, win, {
+            inSeconds: true,
+          });
+        }
+      } else {
+        // If there are any foreground stopwatches running for this window, finish
+        // them and switch to background.
+        if (TelemetryStopwatch.running(FOREGROUND_DURATION_HISTOGRAM_ID, win)) {
+          TelemetryStopwatch.finish(FOREGROUND_DURATION_HISTOGRAM_ID, win);
+        }
+
+        if (
+          !TelemetryStopwatch.running(BACKGROUND_DURATION_HISTOGRAM_ID, win)
+        ) {
+          TelemetryStopwatch.start(BACKGROUND_DURATION_HISTOGRAM_ID, win, {
+            inSeconds: true,
+          });
+        }
+      }
+    }
+  },
+
+  /**
+   * Called when the browser UI handles the View:PictureInPicture command via
+   * the keyboard.
+   *
+   * @param {Event} event
+   */
+  onCommand(event) {
+    if (!lazy.PIP_ENABLED) {
+      return;
+    }
+
+    let win = event.target.ownerGlobal;
+    let bc = Services.focus.focusedContentBrowsingContext;
+    if (bc.top == win.gBrowser.selectedBrowser.browsingContext) {
+      let actor = bc.currentWindowGlobal.getActor("PictureInPictureLauncher");
+      actor.sendAsyncMessage("PictureInPicture:KeyToggle");
+    }
+  },
+
+  async focusTabAndClosePip(window, pipActor) {
+    let browser = this.weakWinToBrowser.get(window);
+    if (!browser) {
+      return;
+    }
+
+    let gBrowser = browser.getTabBrowser();
+    let tab = gBrowser.getTabForBrowser(browser);
+
+    // focus the tab's window
+    tab.ownerGlobal.focus();
+
+    gBrowser.selectedTab = tab;
+    await this.closeSinglePipWindow({ reason: "unpip", actorRef: pipActor });
+  },
+
+  /**
+   * Update the respect PiPDisabled pref value when the toggle is clicked.
+   * @param {Event} event The event from toggling the respect
+   *   PiPDisabled in the PiP panel
+   */
+  toggleRespectDisablePip(event) {
+    let toggle = event.target;
+    let respectPipDisabled = !toggle.pressed;
+
+    Services.prefs.setBoolPref(
+      "media.videocontrols.picture-in-picture.respect-disablePictureInPicture",
+      respectPipDisabled
+    );
+
+    Services.telemetry.recordEvent(
+      "pictureinpicture",
+      "disrespect_disable",
+      "urlBar"
+    );
+  },
+
+  /**
+   * Updates the PiP count and PiPDisabled count of eligible PiP videos for a
+   * respective WindowGlobal.
+   * @param {BrowsingContext} browsingContext The BrowsingContext with eligible videos
+   * @param {Object} object
+   *    pipCount: The number of eligible videos for the respective WindowGlobal
+   *    pipDisabledCount: The number of disablePiP videos for the respective WindowGlobal
+   */
+  updateEligiblePipVideoCount(browsingContext, object) {
+    let windowGlobal = browsingContext.currentWindowGlobal;
+
+    if (windowGlobal) {
+      this.weakGlobalToEligiblePipCount.set(windowGlobal, object);
+    }
+  },
+
+  /**
+   * A generator function that yeilds a WindowGlobal, it's respective PiP
+   * count, and if any of the videos have PiPDisabled set.
+   * @param {Browser} browser The selected browser
+   */
+  *windowGlobalPipCountGenerator(browser) {
+    let contextsToVisit = [browser.browsingContext];
+    while (contextsToVisit.length) {
+      let currentBC = contextsToVisit.pop();
+      let windowGlobal = currentBC.currentWindowGlobal;
+
+      if (!windowGlobal) {
+        continue;
+      }
+
+      let { pipCount, pipDisabledCount } =
+        this.weakGlobalToEligiblePipCount.get(windowGlobal) || {
+          pipCount: 0,
+          pipDisabledCount: 0,
+        };
+
+      contextsToVisit.push(...currentBC.children);
+
+      yield { windowGlobal, pipCount, pipDisabledCount };
+    }
+  },
+
+  /**
+   * Gets the total eligible video count and total PiPDisabled count for a
+   * given browser.
+   * @param {Browser} browser The selected browser
+   * @returns Total count of eligible PiP videos for the selected broser
+   */
+  getEligiblePipVideoCount(browser) {
+    let totalPipCount = 0;
+    let totalPipDisabled = 0;
+
+    for (let {
+      pipCount,
+      pipDisabledCount,
+    } of this.windowGlobalPipCountGenerator(browser)) {
+      totalPipCount += pipCount;
+      totalPipDisabled += pipDisabledCount;
+    }
+
+    return { totalPipCount, totalPipDisabled };
+  },
+
+  /**
+   * This function updates the hover text on the urlbar PiP button when we enter or exit PiP
+   * @param {Document} document The window document
+   * @param {Element} pipToggle The urlbar PiP button
+   * @param {String} dataL10nId The data l10n id of the string we want to show
+   */
+  updateUrlbarHoverText(document, pipToggle, dataL10nId) {
+    let shortcut = document.getElementById("key_togglePictureInPicture");
+
+    document.l10n.setAttributes(pipToggle, dataL10nId, {
+      shortcut: ShortcutUtils.prettifyShortcut(shortcut),
+    });
+  },
+
+  /**
+   * Toggles the visibility of the PiP urlbar button. If the total video count
+   * is 1, then we will show the button. If any eligible video has PiPDisabled,
+   * then the button will show. Otherwise the button is hidden.
+   * @param {Browser} browser The selected browser
+   */
+  updateUrlbarToggle(browser) {
+    if (!lazy.PIP_ENABLED || !lazy.PIP_URLBAR_BUTTON) {
+      return;
+    }
+
+    let win = browser.ownerGlobal;
+    if (win.closed || win.gBrowser?.selectedBrowser !== browser) {
+      return;
+    }
+
+    let { totalPipCount, totalPipDisabled } =
+      this.getEligiblePipVideoCount(browser);
+
+    let pipToggle = win.document.getElementById("picture-in-picture-button");
+    pipToggle.hidden = !(
+      totalPipCount === 1 ||
+      (totalPipDisabled > 0 && lazy.RESPECT_PIP_DISABLED)
+    );
+
+    let browserHasPip = !!this.browserWeakMap.get(browser);
+    if (browserHasPip) {
+      this.setUrlbarPipIconActive(browser.ownerGlobal);
+    } else {
+      this.setUrlbarPipIconInactive(browser.ownerGlobal);
+    }
+  },
+
+  /**
+   * Open the PiP panel if any video has PiPDisabled, otherwise finds the
+   * correct WindowGlobal to open the eligible PiP video.
+   * @param {Event} event Event from clicking the PiP urlbar button
+   */
+  toggleUrlbar(event) {
+    if (event.button !== 0) {
+      return;
+    }
+
+    let win = event.target.ownerGlobal;
+    let browser = win.gBrowser.selectedBrowser;
+
+    let pipPanel = this.getPanelForBrowser(browser);
+
+    for (let {
+      windowGlobal,
+      pipCount,
+      pipDisabledCount,
+    } of this.windowGlobalPipCountGenerator(browser)) {
+      if (
+        (pipDisabledCount > 0 && lazy.RESPECT_PIP_DISABLED) ||
+        (pipPanel && pipPanel.state !== "closed")
+      ) {
+        this.togglePipPanel(browser);
+        return;
+      } else if (pipCount === 1) {
+        let actor = windowGlobal.getActor("PictureInPictureToggle");
+        actor.sendAsyncMessage("PictureInPicture:UrlbarToggle");
+        return;
+      }
+    }
+  },
+
+  /**
+   * Set the toggle for PiPDisabled when the panel is shown.
+   * If the pref is set from about:config, we need to update
+   * the toggle switch in the panel to match the pref.
+   * @param {Event} event The panel shown event
+   */
+  onPipPanelShown(event) {
+    let toggle = event.target.querySelector("#respect-pipDisabled-switch");
+    toggle.pressed = !lazy.RESPECT_PIP_DISABLED;
+  },
+
+  /**
+   * Update the visibility of the urlbar PiP button when the panel is hidden.
+   * The button will show when there is more than 1 video and at least 1 video
+   * has PiPDisabled. If we no longer want to respect PiPDisabled then we
+   * need to check if the urlbar button should still be visible.
+   * @param {Event} event The panel hidden event
+   */
+  onPipPanelHidden(event) {
+    this.updateUrlbarToggle(event.view.gBrowser.selectedBrowser);
+  },
+
+  /**
+   * Create the PiP panel if needed and toggle the display of the panel
+   * @param {Browser} browser The current browser
+   */
+  togglePipPanel(browser) {
+    let pipPanel = this.getPanelForBrowser(browser);
+
+    if (pipPanel.state === "closed") {
+      let anchor = browser.ownerDocument.querySelector(
+        "#picture-in-picture-button"
+      );
+
+      pipPanel.openPopup(anchor, "bottomright topright");
+      Services.telemetry.recordEvent(
+        "pictureinpicture",
+        "opened_method",
+        "urlBar",
+        null,
+        { disableDialog: "true" }
+      );
+    } else {
+      pipPanel.hidePopup();
+    }
+  },
+
+  /**
+   * Sets the PiP urlbar to an active state. This changes the icon in the
+   * urlbar button to the unpip icon.
+   * @param {Window} win The current Window
+   */
+  setUrlbarPipIconActive(win) {
+    let pipToggle = win.document.getElementById("picture-in-picture-button");
+    pipToggle.toggleAttribute("pipactive", true);
+
+    this.updateUrlbarHoverText(
+      win.document,
+      pipToggle,
+      "picture-in-picture-urlbar-button-close"
+    );
+  },
+
+  /**
+   * Sets the PiP urlbar to an inactive state. This changes the icon in the
+   * urlbar button to the open pip icon.
+   * @param {Window} win The current window
+   */
+  setUrlbarPipIconInactive(win) {
+    if (!win) {
+      return;
+    }
+    let pipToggle = win.document.getElementById("picture-in-picture-button");
+    pipToggle.toggleAttribute("pipactive", false);
+
+    this.updateUrlbarHoverText(
+      win.document,
+      pipToggle,
+      "picture-in-picture-urlbar-button-open"
+    );
+  },
+
+  /**
+   * Remove attribute which enables pip icon in tab
+   *
+   * @param {Window} window
+   *   A PictureInPicture player's window, used to resolve the player's
+   *   associated originating content browser
+   */
+  clearPipTabIcon(window) {
+    const browser = this.weakWinToBrowser.get(window);
+    if (!browser) {
+      return;
+    }
+
+    // see if no other pip windows are open for this content browser
+    for (let win of Services.wm.getEnumerator(WINDOW_TYPE)) {
+      if (
+        win !== window &&
+        this.weakWinToBrowser.has(win) &&
+        this.weakWinToBrowser.get(win) === browser
+      ) {
+        return;
+      }
+    }
+
+    let gBrowser = browser.getTabBrowser();
+    let tab = gBrowser?.getTabForBrowser(browser);
+    if (tab) {
+      tab.removeAttribute("pictureinpicture");
+    }
+  },
+
+  /**
+   * Closes and waits for passed PiP player window to finish closing.
+   *
+   * @param {Window} pipWin
+   *   Player window to close
+   */
+  async closePipWindow(pipWin) {
+    if (pipWin.closed) {
+      return;
+    }
+    let closedPromise = new Promise(resolve => {
+      pipWin.addEventListener("unload", resolve, { once: true });
+    });
+    pipWin.close();
+    await closedPromise;
+  },
+
+  /**
+   * Closes a single PiP window. Used exclusively in conjunction with support
+   * for multiple PiP windows
+   *
+   * @param {Object} closeData
+   *   Additional data required to complete a close operation on a PiP window
+   * @param {PictureInPictureParent} closeData.actorRef
+   *   The PictureInPictureParent actor associated with the PiP window being closed
+   * @param {string} closeData.reason
+   *   The reason for closing this PiP window
+   */
+  async closeSinglePipWindow(closeData) {
+    const { reason, actorRef } = closeData;
+    const win = this.getWeakPipPlayer(actorRef);
+    if (!win) {
+      return;
+    }
+    this.removePiPBrowserFromWeakMap(this.weakWinToBrowser.get(win));
+
+    Services.telemetry.recordEvent(
+      "pictureinpicture",
+      "closed_method",
+      reason,
+      null
+    );
+    await this.closePipWindow(win);
+  },
+
+  /**
+   * A request has come up from content to open a Picture in Picture
+   * window.
+   *
+   * @param {WindowGlobalParent} wgps
+   *   The WindowGlobalParent that is requesting the Picture in Picture
+   *   window.
+   *
+   * @param {object} videoData
+   *   An object containing the following properties:
+   *
+   *   videoHeight (int):
+   *     The preferred height of the video.
+   *
+   *   videoWidth (int):
+   *     The preferred width of the video.
+   *
+   * @returns {Promise}
+   *   Resolves once the Picture in Picture window has been created, and
+   *   the player component inside it has finished loading.
+   */
+  async handlePictureInPictureRequest(wgp, videoData) {
+    gCurrentPlayerCount += 1;
+
+    Services.telemetry.scalarSetMaximum(
+      "pictureinpicture.most_concurrent_players",
+      gCurrentPlayerCount
+    );
+
+    let browser = wgp.browsingContext.top.embedderElement;
+    let parentWin = browser.ownerGlobal;
+
+    let win = await this.openPipWindow(parentWin, videoData);
+    win.setIsPlayingState(videoData.playing);
+    win.setIsMutedState(videoData.isMuted);
+
+    // set attribute which shows pip icon in tab
+    let tab = parentWin.gBrowser.getTabForBrowser(browser);
+    tab.setAttribute("pictureinpicture", true);
+
+    this.setUrlbarPipIconActive(parentWin);
+
+    tab.addEventListener("TabSwapPictureInPicture", this);
+
+    let pipId = gNextWindowID.toString();
+    win.setupPlayer(pipId, wgp, videoData.videoRef);
+    gNextWindowID++;
+
+    this.weakWinToBrowser.set(win, browser);
+    this.addPiPBrowserToWeakMap(browser);
+    this.addOriginatingWinToWeakMap(browser);
+
+    win.setScrubberPosition(videoData.scrubberPosition);
+    win.setTimestamp(videoData.timestamp);
+
+    Services.prefs.setBoolPref(TOGGLE_HAS_USED_PREF, true);
+
+    let args = {
+      width: win.innerWidth.toString(),
+      height: win.innerHeight.toString(),
+      screenX: win.screenX.toString(),
+      screenY: win.screenY.toString(),
+      ccEnabled: videoData.ccEnabled.toString(),
+      webVTTSubtitles: videoData.webVTTSubtitles.toString(),
+    };
+
+    Services.telemetry.recordEvent(
+      "pictureinpicture",
+      "create",
+      "player",
+      pipId,
+      args
+    );
+  },
+
+  /**
+   * Calls the browsingContext's `forceAppWindowActive` flag to determine if the
+   * the top level chrome browsingContext should be forcefully set as active or not.
+   * When the originating window's browsing context is set to active, captions on the
+   * PiP window are properly updated. Forcing active while a PiP window is open ensures
+   * that captions are still updated when the originating window is occluded.
+   *
+   * @param {BrowsingContext} browsingContext
+   *   The browsing context of the originating window
+   * @param {boolean} isActive
+   *   True to force originating window as active, or false to not enforce it
+   * @see CanonicalBrowsingContext
+   */
+  setOriginatingWindowActive(browsingContext, isActive) {
+    browsingContext.forceAppWindowActive = isActive;
+  },
+
+  /**
+   * unload event has been called in player.js, cleanup our preserved
+   * browser object.
+   *
+   * @param {Window} window
+   */
+  unload(window) {
+    TelemetryStopwatch.finish(
+      "FX_PICTURE_IN_PICTURE_WINDOW_OPEN_DURATION",
+      window
+    );
+
+    if (TelemetryStopwatch.running(BACKGROUND_DURATION_HISTOGRAM_ID, window)) {
+      TelemetryStopwatch.finish(BACKGROUND_DURATION_HISTOGRAM_ID, window);
+    } else if (
+      TelemetryStopwatch.running(FOREGROUND_DURATION_HISTOGRAM_ID, window)
+    ) {
+      TelemetryStopwatch.finish(FOREGROUND_DURATION_HISTOGRAM_ID, window);
+    }
+
+    let browser = this.weakWinToBrowser.get(window);
+    this.removeOriginatingWinFromWeakMap(browser);
+
+    gCurrentPlayerCount -= 1;
+    // Saves the location of the Picture in Picture window
+    this.savePosition(window);
+    this.clearPipTabIcon(window);
+    this.setUrlbarPipIconInactive(browser?.ownerGlobal);
+  },
+
+  /**
+   * Open a Picture in Picture window on the same screen as parentWin,
+   * sized based on the information in videoData.
+   *
+   * @param {ChromeWindow} parentWin
+   *   The window hosting the browser that requested the Picture in
+   *   Picture window.
+   *
+   * @param {object} videoData
+   *   An object containing the following properties:
+   *
+   *   videoHeight (int):
+   *     The preferred height of the video.
+   *
+   *   videoWidth (int):
+   *     The preferred width of the video.
+   *
+   * @param {PictureInPictureParent} actorReference
+   *   Reference to the calling PictureInPictureParent
+   *
+   * @returns {Promise}
+   *   Resolves once the window has opened and loaded the player component.
+   */
+  async openPipWindow(parentWin, videoData) {
+    let { top, left, width, height } = this.fitToScreen(parentWin, videoData);
+
+    let { left: resolvedLeft, top: resolvedTop } = this.resolveOverlapConflicts(
+      left,
+      top,
+      width,
+      height
+    );
+
+    top = Math.round(resolvedTop);
+    left = Math.round(resolvedLeft);
+    width = Math.round(width);
+    height = Math.round(height);
+
+    let features =
+      `${PLAYER_FEATURES},top=${top},left=${left},outerWidth=${width},` +
+      `outerHeight=${height}`;
+    let isPrivate = lazy.PrivateBrowsingUtils.isWindowPrivate(parentWin);
+
+    if (isPrivate) {
+      features += ",private";
+    }
+
+    let pipWindow = Services.ww.openWindow(
+      parentWin,
+      PLAYER_URI,
+      null,
+      features,
+      null
+    );
+
+    TelemetryStopwatch.start(
+      "FX_PICTURE_IN_PICTURE_WINDOW_OPEN_DURATION",
+      pipWindow,
+      {
+        inSeconds: true,
+      }
+    );
+
+    pipWindow.windowUtils.setResizeMargin(RESIZE_MARGIN_PX);
+
+    // If the window is Private the icon will have already been set when
+    // it was opened.
+    if (Services.appinfo.OS == "WINNT" && !isPrivate) {
+      lazy.WindowsUIUtils.setWindowIconNoData(pipWindow);
+    }
+
+    return new Promise(resolve => {
+      pipWindow.addEventListener(
+        "load",
+        () => {
+          resolve(pipWindow);
+        },
+        { once: true }
+      );
+    });
+  },
+
+  /**
+   * This function tries to restore the last known Picture-in-Picture location
+   * and size. If those values are unknown or offscreen, then a default
+   * location and size is used.
+   *
+   * @param {ChromeWindow|PlayerWindow} requestingWin
+   *   The window hosting the browser that requested the Picture in
+   *   Picture window. If this is an existing player window then the returned
+   *   player size and position will be determined based on the existing
+   *   player window's size and position.
+   *
+   * @param {object} videoData
+   *   An object containing the following properties:
+   *
+   *   videoHeight (int):
+   *     The preferred height of the video.
+   *
+   *   videoWidth (int):
+   *     The preferred width of the video.
+   *
+   * @returns {object}
+   *   The size and position for the player window, in CSS pixels relative to
+   *   requestingWin.
+   *
+   *   top (int):
+   *     The top position for the player window.
+   *
+   *   left (int):
+   *     The left position for the player window.
+   *
+   *   width (int):
+   *     The width of the player window.
+   *
+   *   height (int):
+   *     The height of the player window.
+   */
+  fitToScreen(requestingWin, videoData) {
+    let { videoHeight, videoWidth } = videoData;
+
+    const isPlayer = requestingWin.document.location.href == PLAYER_URI;
+
+    let requestingCssToDesktopScale =
+      requestingWin.devicePixelRatio / requestingWin.desktopToDeviceScale;
+
+    let top, left, width, height;
+    if (!isPlayer) {
+      // requestingWin is a content window, load last PiP's dimensions
+      ({ top, left, width, height } = this.loadPosition());
+    } else if (requestingWin.windowState === requestingWin.STATE_FULLSCREEN) {
+      // `requestingWin` is a PiP window and in fullscreen. We stored the size
+      // and position before entering fullscreen and we will use that to
+      // calculate the new position
+      ({ top, left, width, height } = requestingWin.getDeferredResize());
+      left *= requestingCssToDesktopScale;
+      top *= requestingCssToDesktopScale;
+    } else {
+      // requestingWin is a PiP player, conserve its dimensions in this case
+      left = requestingWin.screenX * requestingCssToDesktopScale;
+      top = requestingWin.screenY * requestingCssToDesktopScale;
+      width = requestingWin.outerWidth;
+      height = requestingWin.outerHeight;
+    }
+
+    // Check that previous location and size were loaded.
+    // Note that at this point left and top are in desktop pixels, while width
+    // and height are in CSS pixels.
+    if (!isNaN(top) && !isNaN(left) && !isNaN(width) && !isNaN(height)) {
+      // Get the screen of the last PiP window. PiP screen will be the default
+      // screen if the point was not on a screen.
+      let PiPScreen = this.getWorkingScreen(left, top);
+
+      // Center position of PiP window.
+      let PipScreenCssToDesktopScale =
+        PiPScreen.defaultCSSScaleFactor / PiPScreen.contentsScaleFactor;
+      let centerX = left + (width * PipScreenCssToDesktopScale) / 2;
+      let centerY = top + (height * PipScreenCssToDesktopScale) / 2;
+
+      // We have the screen, now we will get the dimensions of the screen
+      let [PiPScreenLeft, PiPScreenTop, PiPScreenWidth, PiPScreenHeight] =
+        this.getAvailScreenSize(PiPScreen);
+
+      // Check that the center of the last PiP location is within the screen limits
+      // If it's not, then we will use the default size and position
+      if (
+        PiPScreenLeft <= centerX &&
+        centerX <= PiPScreenLeft + PiPScreenWidth &&
+        PiPScreenTop <= centerY &&
+        centerY <= PiPScreenTop + PiPScreenHeight
+      ) {
+        let oldWidthDesktopPix = width * PipScreenCssToDesktopScale;
+
+        // The new PiP window will keep the height of the old
+        // PiP window and adjust the width to the correct ratio
+        width = Math.round((height * videoWidth) / videoHeight);
+
+        // Minimum window size on Windows is 136
+        if (AppConstants.platform == "win") {
+          width = 136 > width ? 136 : width;
+        }
+
+        let widthDesktopPix = width * PipScreenCssToDesktopScale;
+        let heightDesktopPix = height * PipScreenCssToDesktopScale;
+
+        // WIGGLE_ROOM allows the PiP window to be within 5 pixels of the right
+        // side of the screen to stay snapped to the right side
+        const WIGGLE_ROOM = 5;
+        // If the PiP window was right next to the right side of the screen
+        // then move the PiP window to the right the same distance that
+        // the width changes from previous width to current width
+        let rightScreen = PiPScreenLeft + PiPScreenWidth;
+        let distFromRight = rightScreen - (left + widthDesktopPix);
+        if (
+          0 < distFromRight &&
+          distFromRight <= WIGGLE_ROOM + (oldWidthDesktopPix - widthDesktopPix)
+        ) {
+          left += distFromRight;
+        }
+
+        // Checks if some of the PiP window is off screen and
+        // if so it will adjust to move everything on screen
+        if (left < PiPScreenLeft) {
+          // off the left of the screen
+          // slide right
+          left = PiPScreenLeft;
+        }
+        if (top < PiPScreenTop) {
+          // off the top of the screen
+          // slide down
+          top = PiPScreenTop;
+        }
+        if (left + widthDesktopPix > PiPScreenLeft + PiPScreenWidth) {
+          // off the right of the screen
+          // slide left
+          left = PiPScreenLeft + PiPScreenWidth - widthDesktopPix;
+        }
+        if (top + heightDesktopPix > PiPScreenTop + PiPScreenHeight) {
+          // off the bottom of the screen
+          // slide up
+          top = PiPScreenTop + PiPScreenHeight - heightDesktopPix;
+        }
+        // Convert top / left from desktop to requestingWin-relative CSS pixels.
+        top /= requestingCssToDesktopScale;
+        left /= requestingCssToDesktopScale;
+        return { top, left, width, height };
+      }
+    }
+
+    // We don't have the size or position of the last PiP window, so fall
+    // back to calculating the default location.
+    let screen = this.getWorkingScreen(
+      requestingWin.screenX * requestingCssToDesktopScale,
+      requestingWin.screenY * requestingCssToDesktopScale,
+      requestingWin.outerWidth * requestingCssToDesktopScale,
+      requestingWin.outerHeight * requestingCssToDesktopScale
+    );
+    let [screenLeft, screenTop, screenWidth, screenHeight] =
+      this.getAvailScreenSize(screen);
+
+    let screenCssToDesktopScale =
+      screen.defaultCSSScaleFactor / screen.contentsScaleFactor;
+
+    // The Picture in Picture window will be a maximum of a quarter of
+    // the screen height, and a third of the screen width.
+    const MAX_HEIGHT = screenHeight / 4;
+    const MAX_WIDTH = screenWidth / 3;
+
+    width = videoWidth * screenCssToDesktopScale;
+    height = videoHeight * screenCssToDesktopScale;
+    let aspectRatio = videoWidth / videoHeight;
+
+    if (videoHeight > MAX_HEIGHT || videoWidth > MAX_WIDTH) {
+      // We're bigger than the max.
+      // Take the largest dimension and clamp it to the associated max.
+      // Recalculate the other dimension to maintain aspect ratio.
+      if (videoWidth >= videoHeight) {
+        // We're clamping the width, so the height must be adjusted to match
+        // the original aspect ratio. Since aspect ratio is width over height,
+        // that means we need to _divide_ the MAX_WIDTH by the aspect ratio to
+        // calculate the appropriate height.
+        width = MAX_WIDTH;
+        height = Math.round(MAX_WIDTH / aspectRatio);
+      } else {
+        // We're clamping the height, so the width must be adjusted to match
+        // the original aspect ratio. Since aspect ratio is width over height,
+        // this means we need to _multiply_ the MAX_HEIGHT by the aspect ratio
+        // to calculate the appropriate width.
+        height = MAX_HEIGHT;
+        width = Math.round(MAX_HEIGHT * aspectRatio);
+      }
+    }
+
+    // Now that we have the dimensions of the video, we need to figure out how
+    // to position it in the bottom right corner. Since we know the width of the
+    // available rect, we need to subtract the dimensions of the window we're
+    // opening to get the top left coordinates that openWindow expects.
+    //
+    // In event that the user has multiple displays connected, we have to
+    // calculate the top-left coordinate of the new window in absolute
+    // coordinates that span the entire display space, since this is what the
+    // openWindow expects for its top and left feature values.
+    //
+    // The screenWidth and screenHeight values only tell us the available
+    // dimensions on the screen that the parent window is on. We add these to
+    // the screenLeft and screenTop values, which tell us where this screen is
+    // located relative to the "origin" in absolute coordinates.
+    let isRTL = Services.locale.isAppLocaleRTL;
+    left = isRTL ? screenLeft : screenLeft + screenWidth - width;
+    top = screenTop + screenHeight - height;
+
+    // Convert top/left from desktop pixels to requestingWin-relative CSS
+    // pixels, and width / height to the target screen's CSS pixels, which is
+    // what we've made the size calculation against.
+    top /= requestingCssToDesktopScale;
+    left /= requestingCssToDesktopScale;
+    width /= screenCssToDesktopScale;
+    height /= screenCssToDesktopScale;
+
+    return { top, left, width, height };
+  },
+
+  /**
+   * This function will take the size and potential location of a new
+   * Picture-in-Picture player window, and try to return the location
+   * coordinates that will best ensure that the player window will not overlap
+   * with other pre-existing player windows.
+   *
+   * @param {int} left
+   *  x position of left edge for Picture-in-Picture window that is being
+   *  opened
+   * @param {int} top
+   *  y position of top edge for Picture-in-Picture window that is being
+   *  opened
+   * @param {int} width
+   *  Width of Picture-in-Picture window that is being opened
+   * @param {int} height
+   *  Height of Picture-in-Picture window that is being opened
+   *
+   * @returns {object}
+   *  An object with the following properties:
+   *
+   *   top (int):
+   *     The recommended top position for the player window.
+   *
+   *   left (int):
+   *     The recommended left position for the player window.
+   */
+  resolveOverlapConflicts(left, top, width, height) {
+    // This algorithm works by first identifying the possible candidate
+    // locations that the new player window could be placed without overlapping
+    // other player windows (assuming that a confict is discovered at all of
+    // course). The optimal candidate is then selected by its distance to the
+    // original conflict, shorter distances are better.
+    //
+    // Candidates are discovered by iterating over each of the sides of every
+    // pre-existing player window. One candidate is collected for each side.
+    // This is done to ensure that the new player window will be opened to
+    // tightly fit along the edge of another player window.
+    //
+    // These candidates are then pruned for candidates that will introduce
+    // further conflicts. Finally the ideal candidate is selected from this
+    // pool of remaining candidates, optimized for minimizing distance to
+    // the original conflict.
+    let playerRects = [];
+
+    for (let playerWin of Services.wm.getEnumerator(WINDOW_TYPE)) {
+      playerRects.push(
+        new Rect(
+          playerWin.screenX,
+          playerWin.screenY,
+          playerWin.outerWidth,
+          playerWin.outerHeight
+        )
+      );
+    }
+
+    const newPlayerRect = new Rect(left, top, width, height);
+    let conflictingPipRect = playerRects.find(rect =>
+      rect.intersects(newPlayerRect)
+    );
+
+    if (!conflictingPipRect) {
+      // no conflicts found
+      return { left, top };
+    }
+
+    const conflictLoc = conflictingPipRect.center();
+
+    // Will try to resolve a better placement only on the screen where
+    // the conflict occurred
+    const conflictScreen = this.getWorkingScreen(conflictLoc.x, conflictLoc.y);
+
+    const [screenTop, screenLeft, screenWidth, screenHeight] =
+      this.getAvailScreenSize(conflictScreen);
+
+    const screenRect = new Rect(
+      screenTop,
+      screenLeft,
+      screenWidth,
+      screenHeight
+    );
+
+    const getEdgeCandidates = rect => {
+      return [
+        // left edge's candidate
+        new Point(rect.left - newPlayerRect.width, rect.top),
+        // top edge's candidate
+        new Point(rect.left, rect.top - newPlayerRect.height),
+        // right edge's candidate
+        new Point(rect.right + newPlayerRect.width, rect.top),
+        // bottom edge's candidate
+        new Point(rect.left, rect.bottom),
+      ];
+    };
+
+    let candidateLocations = [];
+    for (const playerRect of playerRects) {
+      for (let candidateLoc of getEdgeCandidates(playerRect)) {
+        const candidateRect = new Rect(
+          candidateLoc.x,
+          candidateLoc.y,
+          width,
+          height
+        );
+
+        if (!screenRect.contains(candidateRect)) {
+          continue;
+        }
+
+        // test that no PiPs conflict with this candidate box
+        if (playerRects.some(rect => rect.intersects(candidateRect))) {
+          continue;
+        }
+
+        const candidateCenter = candidateRect.center();
+        const candidateDistanceToConflict =
+          Math.abs(conflictLoc.x - candidateCenter.x) +
+          Math.abs(conflictLoc.y - candidateCenter.y);
+
+        candidateLocations.push({
+          distanceToConflict: candidateDistanceToConflict,
+          location: candidateLoc,
+        });
+      }
+    }
+
+    if (!candidateLocations.length) {
+      // if no suitable candidates can be found, return the original location
+      return { left, top };
+    }
+
+    // sort candidates by distance to the conflict, select the closest
+    const closestCandidate = candidateLocations.sort(
+      (firstCand, secondCand) =>
+        firstCand.distanceToConflict - secondCand.distanceToConflict
+    )[0];
+
+    if (!closestCandidate) {
+      // can occur if there were no valid candidates, return original location
+      return { left, top };
+    }
+
+    const resolvedX = closestCandidate.location.x;
+    const resolvedY = closestCandidate.location.y;
+
+    return { left: resolvedX, top: resolvedY };
+  },
+
+  /**
+   * Resizes the the PictureInPicture player window.
+   *
+   * @param {object} videoData
+   *    The source video's data.
+   * @param {PictureInPictureParent} actorRef
+   *    Reference to the PictureInPicture parent actor.
+   */
+  resizePictureInPictureWindow(videoData, actorRef) {
+    let win = this.getWeakPipPlayer(actorRef);
+
+    if (!win) {
+      return;
+    }
+
+    win.resizeToVideo(this.fitToScreen(win, videoData));
+  },
+
+  /**
+   * Opens the context menu for toggling PictureInPicture.
+   *
+   * @param {Window} window
+   * @param {object} data
+   *  Message data from the PictureInPictureToggleParent
+   */
+  openToggleContextMenu(window, data) {
+    let document = window.document;
+    let popup = document.getElementById("pictureInPictureToggleContextMenu");
+    let contextMoveToggle = document.getElementById(
+      "context_MovePictureInPictureToggle"
+    );
+
+    // Set directional string for toggle position
+    let position = Services.prefs.getStringPref(
+      TOGGLE_POSITION_PREF,
+      TOGGLE_POSITION_RIGHT
+    );
+    switch (position) {
+      case TOGGLE_POSITION_RIGHT:
+        document.l10n.setAttributes(
+          contextMoveToggle,
+          "picture-in-picture-move-toggle-left"
+        );
+        break;
+      case TOGGLE_POSITION_LEFT:
+        document.l10n.setAttributes(
+          contextMoveToggle,
+          "picture-in-picture-move-toggle-right"
+        );
+        break;
+    }
+
+    // We synthesize a new MouseEvent to propagate the inputSource to the
+    // subsequently triggered popupshowing event.
+    let newEvent = document.createEvent("MouseEvent");
+    let screenX = data.screenXDevPx / window.devicePixelRatio;
+    let screenY = data.screenYDevPx / window.devicePixelRatio;
+    newEvent.initNSMouseEvent(
+      "contextmenu",
+      true,
+      true,
+      null,
+      0,
+      screenX,
+      screenY,
+      0,
+      0,
+      false,
+      false,
+      false,
+      false,
+      0,
+      null,
+      0,
+      data.mozInputSource
+    );
+    popup.openPopupAtScreen(newEvent.screenX, newEvent.screenY, true, newEvent);
+  },
+
+  hideToggle() {
+    Services.prefs.setBoolPref(TOGGLE_ENABLED_PREF, false);
+    Services.telemetry.recordEvent(
+      "pictureinpicture.settings",
+      "disable",
+      "player"
+    );
+  },
+
+  /**
+   * This is used in AsyncTabSwitcher.jsm and tabbrowser.js to check if the browser
+   * currently has a PiP window.
+   * If the browser has a PiP window we want to keep the browser in an active state because
+   * the browser is still partially visible.
+   * @param browser The browser to check if it has a PiP window
+   * @returns true if browser has PiP window else false
+   */
+  isOriginatingBrowser(browser) {
+    return this.browserWeakMap.has(browser);
+  },
+
+  moveToggle() {
+    // Get the current position
+    let position = Services.prefs.getStringPref(
+      TOGGLE_POSITION_PREF,
+      TOGGLE_POSITION_RIGHT
+    );
+    let newPosition = "";
+    // Determine what the opposite position would be for that preference
+    switch (position) {
+      case TOGGLE_POSITION_RIGHT:
+        newPosition = TOGGLE_POSITION_LEFT;
+        break;
+      case TOGGLE_POSITION_LEFT:
+        newPosition = TOGGLE_POSITION_RIGHT;
+        break;
+    }
+    if (newPosition) {
+      Services.prefs.setStringPref(TOGGLE_POSITION_PREF, newPosition);
+    }
+  },
+
+  /**
+   * This function takes a screen and will return the left, top, width and
+   * height of the screen
+   * @param {Screen} screen
+   * The screen we need to get the size and coordinates of
+   *
+   * @returns {array}
+   * Size and location of screen in desktop pixels.
+   *
+   *   screenLeft.value (int):
+   *     The left position for the screen.
+   *
+   *   screenTop.value (int):
+   *     The top position for the screen.
+   *
+   *   screenWidth.value (int):
+   *     The width of the screen.
+   *
+   *   screenHeight.value (int):
+   *     The height of the screen.
+   */
+  getAvailScreenSize(screen) {
+    let screenLeft = {},
+      screenTop = {},
+      screenWidth = {},
+      screenHeight = {};
+    screen.GetAvailRectDisplayPix(
+      screenLeft,
+      screenTop,
+      screenWidth,
+      screenHeight
+    );
+    return [
+      screenLeft.value,
+      screenTop.value,
+      screenWidth.value,
+      screenHeight.value,
+    ];
+  },
+
+  /**
+   * This function takes in a rect in desktop pixels, and returns the screen it
+   * is located on.
+   *
+   * If the left and top are not on any screen, it will return the default
+   * screen.
+   *
+   * @param {int} left
+   *  left or x coordinate
+   *
+   * @param {int} top
+   *  top or y coordinate
+   *
+   * @param {int} width
+   *  top or y coordinate
+   *
+   * @param {int} height
+   *  top or y coordinate
+   *
+   * @returns {Screen} screen
+   *  the screen the left and top are on otherwise, default screen
+   */
+  getWorkingScreen(left, top, width = 1, height = 1) {
+    // Get the screen manager
+    let screenManager = Cc["@mozilla.org/gfx/screenmanager;1"].getService(
+      Ci.nsIScreenManager
+    );
+    // use screenForRect to get screen
+    // this returns the default screen if left and top are not
+    // on any screen
+    return screenManager.screenForRect(left, top, width, height);
+  },
+
+  /**
+   * Saves position and size of Picture-in-Picture window
+   * @param {Window} win The Picture-in-Picture window
+   */
+  savePosition(win) {
+    let xulStore = Services.xulStore;
+
+    // We store left / top position in desktop pixels, like SessionStore does,
+    // so that we can restore them properly (as CSS pixels need to be relative
+    // to a screen, and we won't have a target screen to restore).
+    let cssToDesktopScale = win.devicePixelRatio / win.desktopToDeviceScale;
+
+    let left = win.screenX * cssToDesktopScale;
+    let top = win.screenY * cssToDesktopScale;
+    let width = win.outerWidth;
+    let height = win.outerHeight;
+
+    xulStore.setValue(PLAYER_URI, "picture-in-picture", "left", left);
+    xulStore.setValue(PLAYER_URI, "picture-in-picture", "top", top);
+    xulStore.setValue(PLAYER_URI, "picture-in-picture", "width", width);
+    xulStore.setValue(PLAYER_URI, "picture-in-picture", "height", height);
+  },
+
+  /**
+   * Load last Picture in Picture location and size
+   * @returns {object}
+   *   The size and position of the last Picture in Picture window.
+   *
+   *   top (int):
+   *     The top position for the last player window.
+   *     Otherwise NaN
+   *
+   *   left (int):
+   *     The left position for the last player window.
+   *     Otherwise NaN
+   *
+   *   width (int):
+   *     The width of the player last window.
+   *     Otherwise NaN
+   *
+   *   height (int):
+   *     The height of the player last window.
+   *     Otherwise NaN
+   */
+  loadPosition() {
+    let xulStore = Services.xulStore;
+
+    let left = parseInt(
+      xulStore.getValue(PLAYER_URI, "picture-in-picture", "left")
+    );
+    let top = parseInt(
+      xulStore.getValue(PLAYER_URI, "picture-in-picture", "top")
+    );
+    let width = parseInt(
+      xulStore.getValue(PLAYER_URI, "picture-in-picture", "width")
+    );
+    let height = parseInt(
+      xulStore.getValue(PLAYER_URI, "picture-in-picture", "height")
+    );
+
+    return { top, left, width, height };
+  },
+
+  setFirstSeen(dateSeconds) {
+    if (!dateSeconds) {
+      return;
+    }
+
+    Services.prefs.setIntPref(TOGGLE_FIRST_SEEN_PREF, dateSeconds);
+  },
+
+  setHasUsed(hasUsed) {
+    Services.prefs.setBoolPref(TOGGLE_HAS_USED_PREF, !!hasUsed);
+  },
+};
diff --git a/toolkit/components/pictureinpicture/PictureInPictureControls.sys.mjs b/toolkit/components/pictureinpicture/PictureInPictureControls.sys.mjs
new file mode 100644
index 0000000000..1f898a9078
--- /dev/null
+++ b/toolkit/components/pictureinpicture/PictureInPictureControls.sys.mjs
@@ -0,0 +1,40 @@
+/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* 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/. */
+
+// These denote which keyboard controls to disable for a qualified video element.
+export const KEYBOARD_CONTROLS = {
+  ALL: 0,
+  PLAY_PAUSE: 1 << 0,
+  MUTE_UNMUTE: 1 << 1,
+  VOLUME: 1 << 2,
+  SEEK: 1 << 3,
+  CLOSE: 1 << 4,
+  LIVE_SEEK: 1 << 5,
+};
+
+// These are the possible toggle positions along the right side of
+// a qualified video element.
+export const TOGGLE_POLICIES = {
+  DEFAULT: 1,
+  HIDDEN: 2,
+  TOP: 3,
+  ONE_QUARTER: 4,
+  MIDDLE: 5,
+  THREE_QUARTERS: 6,
+  BOTTOM: 7,
+};
+
+// These strings are used in the videocontrols.css stylesheet as
+// toggle policy attribute values for setting rules on the position
+// of the toggle.
+export const TOGGLE_POLICY_STRINGS = {
+  [TOGGLE_POLICIES.DEFAULT]: "default",
+  [TOGGLE_POLICIES.HIDDEN]: "hidden",
+  [TOGGLE_POLICIES.TOP]: "top",
+  [TOGGLE_POLICIES.ONE_QUARTER]: "one-quarter",
+  [TOGGLE_POLICIES.MIDDLE]: "middle",
+  [TOGGLE_POLICIES.THREE_QUARTERS]: "three-quarters",
+  [TOGGLE_POLICIES.BOTTOM]: "bottom",
+};
diff --git a/toolkit/components/pictureinpicture/content/pictureInPicturePanel.xhtml b/toolkit/components/pictureinpicture/content/pictureInPicturePanel.xhtml
new file mode 100644
index 0000000000..30d6b93d59
--- /dev/null
+++ b/toolkit/components/pictureinpicture/content/pictureInPicturePanel.xhtml
@@ -0,0 +1,47 @@
+<!-- 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:template id="PictureInPicturePanelTemplate">
+  <panel
+    id="PictureInPicturePanel"
+    class="panel-no-padding"
+    type="arrow"
+    orient="vertical"
+    level="parent"
+    tabspecific="true"
+    onpopupshown="PictureInPicture.onPipPanelShown(event);"
+    onpopuphidden="PictureInPicture.onPipPanelHidden(event)"
+  >
+    <box class="panel-header">
+      <html:h1>
+        <html:span data-l10n-id="picture-in-picture-panel-header" />
+      </html:h1>
+    </box>
+    <toolbarseparator />
+    <vbox id="PictureInPicturePanelBody">
+      <html:div data-l10n-id="picture-in-picture-panel-headline" />
+      <html:div>
+        <html:span
+          class="deemphasized"
+          data-l10n-id="picture-in-picture-panel-body"
+        />
+        <html:a
+          is="moz-support-link"
+          id="pip-learn-more-link"
+          support-page="about-picture-picture-firefox"
+          data-l10n-name="support-link"
+        />
+      </html:div>
+    </vbox>
+    <toolbarseparator />
+    <vbox id="PictureInPicturePanelFooter">
+      <html:moz-toggle
+        id="respect-pipDisabled-switch"
+        data-l10n-id="picture-in-picture-enable-toggle"
+        data-l10n-attrs="label"
+        onclick="PictureInPicture.toggleRespectDisablePip(event);"
+      />
+    </vbox>
+  </panel>
+</html:template>
diff --git a/toolkit/components/pictureinpicture/content/player.js b/toolkit/components/pictureinpicture/content/player.js
new file mode 100644
index 0000000000..531959d849
--- /dev/null
+++ b/toolkit/components/pictureinpicture/content/player.js
@@ -0,0 +1,1283 @@
+/* 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/. */
+
+const { PictureInPicture } = ChromeUtils.importESModule(
+  "resource://gre/modules/PictureInPicture.sys.mjs"
+);
+const { ShortcutUtils } = ChromeUtils.importESModule(
+  "resource://gre/modules/ShortcutUtils.sys.mjs"
+);
+const { DeferredTask } = ChromeUtils.importESModule(
+  "resource://gre/modules/DeferredTask.sys.mjs"
+);
+const { AppConstants } = ChromeUtils.importESModule(
+  "resource://gre/modules/AppConstants.sys.mjs"
+);
+
+const AUDIO_TOGGLE_ENABLED_PREF =
+  "media.videocontrols.picture-in-picture.audio-toggle.enabled";
+const KEYBOARD_CONTROLS_ENABLED_PREF =
+  "media.videocontrols.picture-in-picture.keyboard-controls.enabled";
+const CAPTIONS_ENABLED_PREF =
+  "media.videocontrols.picture-in-picture.display-text-tracks.enabled";
+const CAPTIONS_TOGGLE_ENABLED_PREF =
+  "media.videocontrols.picture-in-picture.display-text-tracks.toggle.enabled";
+const TEXT_TRACK_FONT_SIZE_PREF =
+  "media.videocontrols.picture-in-picture.display-text-tracks.size";
+const IMPROVED_CONTROLS_ENABLED_PREF =
+  "media.videocontrols.picture-in-picture.improved-video-controls.enabled";
+
+// Time to fade the Picture-in-Picture video controls after first opening.
+const CONTROLS_FADE_TIMEOUT_MS = 3000;
+const RESIZE_DEBOUNCE_RATE_MS = 500;
+
+/**
+Quadrants!
+* 2 | 1
+* 3 | 4
+*/
+const TOP_RIGHT_QUADRANT = 1;
+const TOP_LEFT_QUADRANT = 2;
+const BOTTOM_LEFT_QUADRANT = 3;
+const BOTTOM_RIGHT_QUADRANT = 4;
+
+/**
+ * Public function to be called from PictureInPicture.jsm. This is the main
+ * entrypoint for initializing the player window.
+ *
+ * @param {Number} id
+ *   A unique numeric ID for the window, used for Telemetry Events.
+ * @param {WindowGlobalParent} wgp
+ *   The WindowGlobalParent that is hosting the originating video.
+ * @param {ContentDOMReference} videoRef
+ *    A reference to the video element that a Picture-in-Picture window
+ *    is being created for
+ */
+function setupPlayer(id, wgp, videoRef) {
+  Player.init(id, wgp, videoRef);
+}
+
+/**
+ * Public function to be called from PictureInPicture.jsm. This update the
+ * controls based on whether or not the video is playing.
+ *
+ * @param {Boolean} isPlaying
+ *   True if the Picture-in-Picture video is playing.
+ */
+function setIsPlayingState(isPlaying) {
+  Player.isPlaying = isPlaying;
+}
+
+/**
+ * Public function to be called from PictureInPicture.jsm. This update the
+ * controls based on whether or not the video is muted.
+ *
+ * @param {Boolean} isMuted
+ *   True if the Picture-in-Picture video is muted.
+ */
+function setIsMutedState(isMuted) {
+  Player.isMuted = isMuted;
+}
+
+/**
+ * Function to resize and reposition the PiP window
+ * @param {Object} rect
+ *   An object containing `left`, `top`, `width`, and `height` for the PiP
+ *   window
+ */
+function resizeToVideo(rect) {
+  Player.resizeToVideo(rect);
+}
+
+/**
+ * Returns an object containing `left`, `top`, `width`, and `height` of the
+ * PiP window before entering fullscreen. Will be null if the PiP window is
+ * not in fullscreen.
+ */
+function getDeferredResize() {
+  return Player.deferredResize;
+}
+
+function enableSubtitlesButton() {
+  Player.enableSubtitlesButton();
+}
+
+function disableSubtitlesButton() {
+  Player.disableSubtitlesButton();
+}
+
+function setScrubberPosition(position) {
+  Player.setScrubberPosition(position);
+}
+
+function setTimestamp(timeString) {
+  Player.setTimestamp(timeString);
+}
+
+/**
+ * The Player object handles initializing the player, holds state, and handles
+ * events for updating state.
+ */
+let Player = {
+  WINDOW_EVENTS: [
+    "click",
+    "contextmenu",
+    "dblclick",
+    "keydown",
+    "mouseup",
+    "mousemove",
+    "MozDOMFullscreen:Entered",
+    "MozDOMFullscreen:Exited",
+    "resize",
+    "unload",
+    "draggableregionleftmousedown",
+  ],
+  actor: null,
+  /**
+   * Used for resizing Telemetry to avoid recording an event for every resize
+   * event. Instead, we wait until RESIZE_DEBOUNCE_RATE_MS has passed since the
+   * last resize event before recording.
+   */
+  resizeDebouncer: null,
+  /**
+   * Used for Telemetry to identify the window.
+   */
+  id: -1,
+
+  /**
+   * When set to a non-null value, a timer is scheduled to hide the controls
+   * after CONTROLS_FADE_TIMEOUT_MS milliseconds.
+   */
+  showingTimeout: null,
+
+  /**
+   * Used to determine old window location when mouseup-ed for corner
+   * snapping drag vector calculation
+   */
+  oldMouseUpWindowX: window.screenX,
+  oldMouseUpWindowY: window.screenY,
+
+  /**
+   * Used to determine if hovering the mouse cursor over the pip window or not.
+   * Gets updated whenever a new hover state is detected.
+   */
+  isCurrentHover: false,
+
+  /**
+   * Store the size and position of the window before entering fullscreen and
+   * use this to correctly position the window when exiting fullscreen
+   */
+  deferredResize: null,
+
+  /**
+   * Initializes the player browser, and sets up the initial state.
+   *
+   * @param {Number} id
+   *   A unique numeric ID for the window, used for Telemetry Events.
+   * @param {WindowGlobalParent} wgp
+   *   The WindowGlobalParent that is hosting the originating video.
+   * @param {ContentDOMReference} videoRef
+   *    A reference to the video element that a Picture-in-Picture window
+   *    is being created for
+   */
+  init(id, wgp, videoRef) {
+    this.id = id;
+
+    // State for whether or not we are adjusting the time via the scrubber
+    this.scrubbing = false;
+
+    let holder = document.querySelector(".player-holder");
+    let browser = document.getElementById("browser");
+    browser.remove();
+
+    browser.setAttribute("nodefaultsrc", "true");
+
+    this.setupTooltip("close", "pictureinpicture-close-btn", "closeShortcut");
+    let strId = this.isFullscreen
+      ? `pictureinpicture-exit-fullscreen-btn2`
+      : `pictureinpicture-fullscreen-btn2`;
+    this.setupTooltip("fullscreen", strId, "fullscreenToggleShortcut");
+
+    // Set the specific remoteType and browsingContextGroupID to use for the
+    // initial about:blank load. The combination of these two properties will
+    // ensure that the browser loads in the same process as our originating
+    // browser.
+    browser.setAttribute("remoteType", wgp.domProcess.remoteType);
+    browser.setAttribute(
+      "initialBrowsingContextGroupId",
+      wgp.browsingContext.group.id
+    );
+    holder.appendChild(browser);
+
+    this.actor =
+      browser.browsingContext.currentWindowGlobal.getActor("PictureInPicture");
+    this.actor.sendAsyncMessage("PictureInPicture:SetupPlayer", {
+      videoRef,
+    });
+
+    PictureInPicture.weakPipToWin.set(this.actor, window);
+
+    for (let eventType of this.WINDOW_EVENTS) {
+      addEventListener(eventType, this);
+    }
+
+    this.controls.addEventListener("mouseleave", () => {
+      this.onMouseLeave();
+    });
+    this.controls.addEventListener("mouseenter", () => {
+      this.onMouseEnter();
+    });
+
+    this.scrubber.addEventListener("input", event => {
+      this.handleScrubbing(event);
+    });
+    this.scrubber.addEventListener("change", event => {
+      this.handleScrubbingDone(event);
+    });
+
+    for (let radio of document.querySelectorAll(
+      'input[type=radio][name="cc-size"]'
+    )) {
+      radio.addEventListener("change", event => {
+        this.onSubtitleChange(event.target.id);
+      });
+    }
+
+    document
+      .querySelector("#subtitles-toggle")
+      .addEventListener("change", () => {
+        this.onToggleChange();
+      });
+
+    // If the content process hosting the video crashes, let's
+    // just close the window for now.
+    browser.addEventListener("oop-browser-crashed", this);
+
+    this.revealControls(false);
+
+    if (Services.prefs.getBoolPref(AUDIO_TOGGLE_ENABLED_PREF, false)) {
+      const audioButton = document.getElementById("audio");
+      audioButton.hidden = false;
+    }
+
+    if (Services.prefs.getBoolPref(CAPTIONS_ENABLED_PREF, false)) {
+      this.closedCaptionButton.hidden = false;
+    }
+
+    if (Services.prefs.getBoolPref(IMPROVED_CONTROLS_ENABLED_PREF, false)) {
+      const fullscreenButton = document.getElementById("fullscreen");
+      fullscreenButton.hidden = false;
+
+      const seekBackwardButton = document.getElementById("seekBackward");
+      seekBackwardButton.hidden = false;
+
+      const seekForwardButton = document.getElementById("seekForward");
+      seekForwardButton.hidden = false;
+
+      this.scrubber.hidden = false;
+      this.timestamp.hidden = false;
+
+      const controlsBottomGradient = document.getElementById(
+        "controls-bottom-gradient"
+      );
+      controlsBottomGradient.hidden = false;
+    }
+
+    this.alignEndControlsButtonTooltips();
+
+    this.resizeDebouncer = new DeferredTask(() => {
+      this.alignEndControlsButtonTooltips();
+      this.recordEvent("resize", {
+        width: window.outerWidth.toString(),
+        height: window.outerHeight.toString(),
+      });
+    }, RESIZE_DEBOUNCE_RATE_MS);
+
+    this.computeAndSetMinimumSize(window.outerWidth, window.outerHeight);
+
+    // alwaysontop windows are not focused by default, so we have to do it
+    // ourselves. We use requestAnimationFrame since we have to wait until the
+    // window is visible before it can focus.
+    window.requestAnimationFrame(() => {
+      window.focus();
+    });
+
+    let fontSize = Services.prefs.getCharPref(
+      TEXT_TRACK_FONT_SIZE_PREF,
+      "medium"
+    );
+
+    // fallback to medium if the pref value is not a valid option
+    if (fontSize === "small" || fontSize === "large") {
+      document.querySelector(`#${fontSize}`).checked = "true";
+    } else {
+      document.querySelector("#medium").checked = "true";
+    }
+  },
+
+  uninit() {
+    this.resizeDebouncer.disarm();
+    PictureInPicture.unload(window, this.actor);
+  },
+
+  setupTooltip(elId, l10nId, shortcutId) {
+    const el = document.getElementById(elId);
+    const shortcut = document.getElementById(shortcutId);
+    let l10nObj = shortcut
+      ? { shortcut: ShortcutUtils.prettifyShortcut(shortcut) }
+      : {};
+    document.l10n.setAttributes(el, l10nId, l10nObj);
+  },
+
+  handleEvent(event) {
+    switch (event.type) {
+      case "click": {
+        // Don't run onClick if middle or right click is pressed respectively
+        if (event.button !== 1 && event.button !== 2) {
+          this.onClick(event);
+          this.controls.removeAttribute("keying");
+        }
+        break;
+      }
+
+      case "contextmenu": {
+        event.preventDefault();
+        break;
+      }
+
+      case "dblclick": {
+        this.onDblClick(event);
+        break;
+      }
+
+      case "keydown": {
+        if (event.keyCode == KeyEvent.DOM_VK_TAB) {
+          this.controls.setAttribute("keying", true);
+          this.showVideoControls();
+        } else if (event.keyCode == KeyEvent.DOM_VK_ESCAPE) {
+          let isSettingsPanelInFocus = this.settingsPanel.contains(
+            document.activeElement
+          );
+
+          event.preventDefault();
+
+          if (!this.settingsPanel.classList.contains("hide")) {
+            // If the subtitles settings panel is open, let the ESC key close it
+            this.toggleSubtitlesSettingsPanel({ forceHide: true });
+            if (isSettingsPanelInFocus) {
+              document.getElementById("closed-caption").focus();
+            }
+          } else if (this.isFullscreen) {
+            // We handle the ESC key, in fullscreen modus as intent to leave only the fullscreen mode
+            document.exitFullscreen();
+          } else {
+            // We handle the ESC key, as an intent to leave the picture-in-picture modus
+            this.onClose();
+          }
+        } else if (
+          Services.prefs.getBoolPref(KEYBOARD_CONTROLS_ENABLED_PREF, false) &&
+          (event.keyCode != KeyEvent.DOM_VK_SPACE || !event.target.id)
+        ) {
+          // Pressing "space" fires a "keydown" event which can also trigger a control
+          // button's "click" event. Handle the "keydown" event only when the event did
+          // not originate from a control button and it is not a "space" keypress.
+          this.onKeyDown(event);
+        }
+
+        break;
+      }
+
+      case "mouseup": {
+        this.onMouseUp(event);
+        break;
+      }
+
+      case "mousemove": {
+        this.onMouseMove();
+        break;
+      }
+
+      // Normally, the DOMFullscreenParent / DOMFullscreenChild actors
+      // would take care of firing the `fullscreen-painted` notification,
+      // however, those actors are only ever instantiated when a <browser>
+      // is fullscreened, and not a <body> element in a parent-process
+      // chrome privileged DOM window.
+      //
+      // Rather than trying to re-engineer JSWindowActors to be re-usable for
+      // this edge-case, we do the work of firing fullscreen-painted when
+      // transitioning in and out of fullscreen ourselves here.
+      case "MozDOMFullscreen:Entered":
+      // Intentional fall-through
+      case "MozDOMFullscreen:Exited": {
+        let { lastTransactionId } = window.windowUtils;
+        window.addEventListener("MozAfterPaint", function onPainted(event) {
+          if (event.transactionId > lastTransactionId) {
+            window.removeEventListener("MozAfterPaint", onPainted);
+            Services.obs.notifyObservers(window, "fullscreen-painted");
+          }
+        });
+
+        // If we are exiting fullscreen we want to resize the window to the
+        // stored size and position
+        if (this.deferredResize && event.type === "MozDOMFullscreen:Exited") {
+          this.resizeToVideo(this.deferredResize);
+          this.deferredResize = null;
+        }
+
+        // Sets the title for fullscreen button when PIP is in Enter Fullscreen mode and Exit Fullscreen mode
+        let strId = this.isFullscreen
+          ? `pictureinpicture-exit-fullscreen-btn2`
+          : `pictureinpicture-fullscreen-btn2`;
+        this.setupTooltip("fullscreen", strId, "fullscreenToggleShortcut");
+
+        window.focus();
+
+        if (this.isFullscreen) {
+          this.actor.sendAsyncMessage("PictureInPicture:EnterFullscreen", {
+            isFullscreen: true,
+            isVideoControlsShowing: null,
+            playerBottomControlsDOMRect: null,
+          });
+        } else {
+          this.actor.sendAsyncMessage("PictureInPicture:ExitFullscreen", {
+            isFullscreen: this.isFullscreen,
+            isVideoControlsShowing:
+              !!this.controls.getAttribute("showing") ||
+              !!this.controls.getAttribute("keying"),
+            playerBottomControlsDOMRect:
+              this.controlsBottom.getBoundingClientRect(),
+          });
+        }
+        // The subtitles settings panel gets selected when entering/exiting fullscreen even though
+        // user-select is set to none. I don't know why this happens or how to prevent so we just
+        // remove the selection when fullscreen is entered/exited.
+        let selection = window.getSelection();
+        selection.removeAllRanges();
+        break;
+      }
+
+      case "oop-browser-crashed": {
+        this.closePipWindow({ reason: "browser-crash" });
+        break;
+      }
+
+      case "resize": {
+        this.onResize(event);
+        break;
+      }
+
+      case "unload": {
+        this.uninit();
+        break;
+      }
+
+      case "draggableregionleftmousedown": {
+        this.toggleSubtitlesSettingsPanel({ forceHide: true });
+        break;
+      }
+    }
+  },
+
+  /**
+   * This function handles when the scrubber is being scrubbed by the mouse
+   * because if we get an input event from the keyboard, onKeyDown will set
+   * this.preventNextInputEvent to true.
+   * This function is called by input events on the scrubber
+   * @param {Event} event The input event
+   */
+  handleScrubbing(event) {
+    // When using the keyboard to scrub, we get both a keydown and an input
+    // event. The input event is fired after the keydown and we have already
+    // handle the keydown event in onKeyDown and we don't want to handle it twice
+    if (this.preventNextInputEvent) {
+      this.preventNextInputEvent = false;
+      return;
+    }
+    if (!this.scrubbing) {
+      this.wasPlaying = this.isPlaying;
+      if (this.isPlaying) {
+        this.actor.sendAsyncMessage("PictureInPicture:Pause");
+      }
+      this.scrubbing = true;
+    }
+    let scrubberPosition = this.getScrubberPositionFromEvent(event);
+    this.setVideoTime(scrubberPosition);
+  },
+
+  /**
+   * This function handles setting the scrubbing state to false and playing
+   * the video if we paused it before scrubbing.
+   * @param {Event} event The change event
+   */
+  handleScrubbingDone(event) {
+    if (!this.scrubbing) {
+      return;
+    }
+    let scrubberPosition = this.getScrubberPositionFromEvent(event);
+    this.setVideoTime(scrubberPosition);
+    if (this.wasPlaying) {
+      this.actor.sendAsyncMessage("PictureInPicture:Play");
+    }
+    this.scrubbing = false;
+  },
+
+  getScrubberPositionFromEvent(event) {
+    return event.target.value;
+  },
+
+  setVideoTime(scrubberPosition) {
+    let wasPlaying = this.scrubbing ? this.wasPlaying : this.isPlaying;
+    this.setScrubberPosition(scrubberPosition);
+    this.actor.sendAsyncMessage("PictureInPicture:SetVideoTime", {
+      scrubberPosition,
+      wasPlaying,
+    });
+  },
+
+  setScrubberPosition(value) {
+    this.scrubber.value = value;
+    this.scrubber.hidden = value === undefined;
+
+    // Also hide the seek buttons when we hide the scrubber
+    this.seekBackward.hidden = value === undefined;
+    this.seekForward.hidden = value === undefined;
+  },
+
+  setTimestamp(timestamp) {
+    this.timestamp.textContent = timestamp;
+    this.timestamp.hidden = timestamp === undefined;
+  },
+
+  closePipWindow(closeData) {
+    // Set the subtitles font size prefs
+    Services.prefs.setBoolPref(
+      CAPTIONS_TOGGLE_ENABLED_PREF,
+      document.querySelector("#subtitles-toggle").checked
+    );
+    for (let radio of document.querySelectorAll(
+      'input[type=radio][name="cc-size"]'
+    )) {
+      if (radio.checked) {
+        Services.prefs.setCharPref(TEXT_TRACK_FONT_SIZE_PREF, radio.id);
+        break;
+      }
+    }
+    const { reason } = closeData;
+    PictureInPicture.closeSinglePipWindow({ reason, actorRef: this.actor });
+  },
+
+  onDblClick(event) {
+    if (event.target.id == "controls") {
+      this.fullscreenModeToggle();
+      event.preventDefault();
+    }
+  },
+
+  onClick(event) {
+    switch (event.target.id) {
+      case "audio": {
+        if (this.isMuted) {
+          this.actor.sendAsyncMessage("PictureInPicture:Unmute");
+        } else {
+          this.actor.sendAsyncMessage("PictureInPicture:Mute");
+        }
+        break;
+      }
+
+      case "close": {
+        this.onClose();
+        break;
+      }
+
+      case "playpause": {
+        if (!this.isPlaying) {
+          this.actor.sendAsyncMessage("PictureInPicture:Play");
+          this.revealControls(false);
+        } else {
+          this.actor.sendAsyncMessage("PictureInPicture:Pause");
+          this.revealControls(true);
+        }
+
+        break;
+      }
+
+      case "seekBackward": {
+        this.actor.sendAsyncMessage("PictureInPicture:SeekBackward");
+        break;
+      }
+
+      case "seekForward": {
+        this.actor.sendAsyncMessage("PictureInPicture:SeekForward");
+        break;
+      }
+
+      case "unpip": {
+        PictureInPicture.focusTabAndClosePip(window, this.actor);
+        break;
+      }
+
+      case "closed-caption": {
+        let options = {};
+        if (event.mozInputSource == MouseEvent.MOZ_SOURCE_KEYBOARD) {
+          options.isKeyboard = true;
+        }
+        this.toggleSubtitlesSettingsPanel(options);
+        // Early return to prevent hiding the panel below
+        return;
+      }
+
+      case "fullscreen": {
+        this.fullscreenModeToggle();
+        this.recordEvent("fullscreen", {
+          enter: (!this.isFullscreen).toString(),
+        });
+        break;
+      }
+
+      case "font-size-selection-radio-small": {
+        document.getElementById("small").click();
+        break;
+      }
+
+      case "font-size-selection-radio-medium": {
+        document.getElementById("medium").click();
+        break;
+      }
+
+      case "font-size-selection-radio-large": {
+        document.getElementById("large").click();
+        break;
+      }
+    }
+    // If the click came from a element that is not inside the subtitles settings panel
+    // then we want to hide the panel
+    if (!this.settingsPanel.contains(event.target)) {
+      this.toggleSubtitlesSettingsPanel({ forceHide: true });
+    }
+  },
+
+  /**
+   * Function to toggle the visibility of the subtitles settings panel
+   * @param {Object} options [optional] Object containing options for the function
+   *   - forceHide: true to force hide the subtitles settings panel
+   *   - isKeyboard: true if the subtitles button was activated using the keyboard
+   *     to show or hide the subtitles settings panel
+   */
+  toggleSubtitlesSettingsPanel(options) {
+    let settingsPanelVisible = !this.settingsPanel.classList.contains("hide");
+    if (options?.forceHide || settingsPanelVisible) {
+      this.settingsPanel.classList.add("hide");
+      this.closedCaptionButton.setAttribute("aria-expanded", false);
+      this.controls.removeAttribute("donthide");
+
+      if (
+        this.controls.getAttribute("keying") ||
+        this.isCurrentHover ||
+        this.controls.getAttribute("showing")
+      ) {
+        return;
+      }
+
+      this.actor.sendAsyncMessage("PictureInPicture:HideVideoControls", {
+        isFullscreen: this.isFullscreen,
+        isVideoControlsShowing: false,
+        playerBottomControlsDOMRect: null,
+      });
+    } else {
+      this.settingsPanel.classList.remove("hide");
+      this.closedCaptionButton.setAttribute("aria-expanded", true);
+      this.controls.setAttribute("donthide", true);
+      this.showVideoControls();
+
+      if (options?.isKeyboard) {
+        document.querySelector("#subtitles-toggle").focus();
+      }
+    }
+  },
+
+  onClose() {
+    this.actor.sendAsyncMessage("PictureInPicture:Pause", {
+      reason: "pip-closed",
+    });
+    this.closePipWindow({ reason: "closeButton" });
+  },
+
+  fullscreenModeToggle() {
+    if (this.isFullscreen) {
+      document.exitFullscreen();
+    } else {
+      this.deferredResize = {
+        left: window.screenX,
+        top: window.screenY,
+        width: window.innerWidth,
+        height: window.innerHeight,
+      };
+      document.body.requestFullscreen();
+    }
+  },
+
+  resizeToVideo(rect) {
+    if (this.isFullscreen) {
+      // We store the size and position because resizing the PiP window
+      // while fullscreened will cause issues
+      this.deferredResize = rect;
+    } else {
+      let { left, top, width, height } = rect;
+      window.resizeTo(width, height);
+      window.moveTo(left, top);
+    }
+  },
+
+  onKeyDown(event) {
+    // We don't want to send a keydown event if the event target was one of the
+    // font sizes in the settings panel
+    if (
+      event.target.parentElement?.parentElement?.classList?.contains(
+        "font-size-selection"
+      )
+    ) {
+      return;
+    }
+
+    let eventKeys = {
+      altKey: event.altKey,
+      shiftKey: event.shiftKey,
+      metaKey: event.metaKey,
+      ctrlKey: event.ctrlKey,
+      keyCode: event.keyCode,
+    };
+
+    // If the up or down arrow is pressed while the scrubber is focused then we
+    // want to hijack these keydown events to act as left or right arrow
+    // respectively to correctly seek the video.
+    if (
+      event.target.id === "scrubber" &&
+      event.keyCode === window.KeyEvent.DOM_VK_UP
+    ) {
+      eventKeys.keyCode = window.KeyEvent.DOM_VK_RIGHT;
+    } else if (
+      event.target.id === "scrubber" &&
+      event.keyCode === window.KeyEvent.DOM_VK_DOWN
+    ) {
+      eventKeys.keyCode = window.KeyEvent.DOM_VK_LEFT;
+    }
+
+    // If the keydown event was one of the arrow keys and the scrubber was
+    // focused then we will also get an input event that will overwrite the
+    // keydown event if we dont' prevent the input event.
+    if (
+      event.target.id === "scrubber" &&
+      [
+        window.KeyEvent.DOM_VK_LEFT,
+        window.KeyEvent.DOM_VK_RIGHT,
+        window.KeyEvent.DOM_VK_UP,
+        window.KeyEvent.DOM_VK_DOWN,
+      ].includes(event.keyCode)
+    ) {
+      this.preventNextInputEvent = true;
+    }
+
+    this.actor.sendAsyncMessage("PictureInPicture:KeyDown", eventKeys);
+  },
+
+  onSubtitleChange(size) {
+    Services.prefs.setCharPref(TEXT_TRACK_FONT_SIZE_PREF, size);
+
+    this.actor.sendAsyncMessage("PictureInPicture:ChangeFontSizeTextTracks");
+  },
+
+  onToggleChange() {
+    // The subtitles toggle has been click in the settings panel so we toggle
+    // the overlay above the font sizes and send a message to toggle the
+    // visibility of the subtitles and set the toggle pref
+    document
+      .querySelector(".font-size-selection")
+      .classList.toggle("font-size-overlay");
+    this.actor.sendAsyncMessage("PictureInPicture:ToggleTextTracks");
+
+    this.captionsToggleEnabled = !this.captionsToggleEnabled;
+    Services.prefs.setBoolPref(
+      CAPTIONS_TOGGLE_ENABLED_PREF,
+      this.captionsToggleEnabled
+    );
+  },
+
+  /**
+   * PiP Corner Snapping Helper Function
+   * Determines the quadrant the PiP window is currently in.
+   */
+  determineCurrentQuadrant() {
+    // Determine center coordinates of window.
+    let windowCenterX = window.screenX + window.innerWidth / 2;
+    let windowCenterY = window.screenY + window.innerHeight / 2;
+    let quadrant = null;
+    let halfWidth = window.screen.availLeft + window.screen.availWidth / 2;
+    let halfHeight = window.screen.availTop + window.screen.availHeight / 2;
+
+    let leftHalf = windowCenterX < halfWidth;
+    let rightHalf = windowCenterX > halfWidth;
+    let topHalf = windowCenterY < halfHeight;
+    let bottomHalf = windowCenterY > halfHeight;
+
+    if (leftHalf && topHalf) {
+      quadrant = TOP_LEFT_QUADRANT;
+    } else if (rightHalf && topHalf) {
+      quadrant = TOP_RIGHT_QUADRANT;
+    } else if (leftHalf && bottomHalf) {
+      quadrant = BOTTOM_LEFT_QUADRANT;
+    } else if (rightHalf && bottomHalf) {
+      quadrant = BOTTOM_RIGHT_QUADRANT;
+    }
+    return quadrant;
+  },
+
+  /**
+   * Helper function to actually move/snap the PiP window.
+   * Moves the PiP window to the top right.
+   */
+  moveToTopRight() {
+    window.moveTo(
+      window.screen.availLeft + window.screen.availWidth - window.innerWidth,
+      window.screen.availTop
+    );
+  },
+
+  /**
+   * Moves the PiP window to the top left.
+   */
+  moveToTopLeft() {
+    window.moveTo(window.screen.availLeft, window.screen.availTop);
+  },
+
+  /**
+   * Moves the PiP window to the bottom right.
+   */
+  moveToBottomRight() {
+    window.moveTo(
+      window.screen.availLeft + window.screen.availWidth - window.innerWidth,
+      window.screen.availTop + window.screen.availHeight - window.innerHeight
+    );
+  },
+
+  /**
+   * Moves the PiP window to the bottom left.
+   */
+  moveToBottomLeft() {
+    window.moveTo(
+      window.screen.availLeft,
+      window.screen.availTop + window.screen.availHeight - window.innerHeight
+    );
+  },
+
+  /**
+   * Uses the PiP window's change in position to determine which direction
+   * the window has been moved in.
+   */
+  determineDirectionDragged() {
+    // Determine change in window location.
+    let deltaX = this.oldMouseUpWindowX - window.screenX;
+    let deltaY = this.oldMouseUpWindowY - window.screenY;
+    let dragDirection = "";
+
+    if (Math.abs(deltaX) > Math.abs(deltaY) && deltaX < 0) {
+      dragDirection = "draggedRight";
+    } else if (Math.abs(deltaX) > Math.abs(deltaY) && deltaX > 0) {
+      dragDirection = "draggedLeft";
+    } else if (Math.abs(deltaX) < Math.abs(deltaY) && deltaY < 0) {
+      dragDirection = "draggedDown";
+    } else if (Math.abs(deltaX) < Math.abs(deltaY) && deltaY > 0) {
+      dragDirection = "draggedUp";
+    }
+    return dragDirection;
+  },
+
+  /**
+   * Event handler for "mouseup" events on the PiP window.
+   *
+   * @param {Event} event
+   *  Event context details
+   */
+  onMouseUp(event) {
+    // Corner snapping changes start here.
+    // Check if metakey pressed and macOS
+    let quadrant = this.determineCurrentQuadrant();
+    let dragAction = this.determineDirectionDragged();
+
+    if (event.metaKey && AppConstants.platform == "macosx" && dragAction) {
+      // Moving logic based on current quadrant and direction of drag.
+      switch (quadrant) {
+        case TOP_RIGHT_QUADRANT:
+          switch (dragAction) {
+            case "draggedRight":
+              this.moveToTopRight();
+              break;
+            case "draggedLeft":
+              this.moveToTopLeft();
+              break;
+            case "draggedDown":
+              this.moveToBottomRight();
+              break;
+            case "draggedUp":
+              this.moveToTopRight();
+              break;
+          }
+          break;
+        case TOP_LEFT_QUADRANT:
+          switch (dragAction) {
+            case "draggedRight":
+              this.moveToTopRight();
+              break;
+            case "draggedLeft":
+              this.moveToTopLeft();
+              break;
+            case "draggedDown":
+              this.moveToBottomLeft();
+              break;
+            case "draggedUp":
+              this.moveToTopLeft();
+              break;
+          }
+          break;
+        case BOTTOM_LEFT_QUADRANT:
+          switch (dragAction) {
+            case "draggedRight":
+              this.moveToBottomRight();
+              break;
+            case "draggedLeft":
+              this.moveToBottomLeft();
+              break;
+            case "draggedDown":
+              this.moveToBottomLeft();
+              break;
+            case "draggedUp":
+              this.moveToTopLeft();
+              break;
+          }
+          break;
+        case BOTTOM_RIGHT_QUADRANT:
+          switch (dragAction) {
+            case "draggedRight":
+              this.moveToBottomRight();
+              break;
+            case "draggedLeft":
+              this.moveToBottomLeft();
+              break;
+            case "draggedDown":
+              this.moveToBottomRight();
+              break;
+            case "draggedUp":
+              this.moveToTopRight();
+              break;
+          }
+          break;
+      } // Switch close.
+    } // Metakey close.
+    this.oldMouseUpWindowX = window.screenX;
+    this.oldMouseUpWindowY = window.screenY;
+  },
+
+  /**
+   * Event handler for mousemove the PiP Window
+   */
+  onMouseMove() {
+    if (this.isFullscreen) {
+      this.revealControls(false);
+    }
+  },
+
+  onMouseEnter() {
+    if (!this.isFullscreen) {
+      this.isCurrentHover = true;
+      this.showVideoControls();
+    }
+  },
+
+  onMouseLeave() {
+    if (!this.isFullscreen) {
+      this.isCurrentHover = false;
+      if (
+        !this.controls.getAttribute("showing") &&
+        !this.controls.getAttribute("keying") &&
+        !this.controls.getAttribute("donthide")
+      ) {
+        this.actor.sendAsyncMessage("PictureInPicture:HideVideoControls", {
+          isFullscreen: this.isFullscreen,
+          isVideoControlsShowing: false,
+          playerBottomControlsDOMRect: null,
+        });
+      }
+    }
+  },
+
+  enableSubtitlesButton() {
+    this.closedCaptionButton.disabled = false;
+
+    this.alignEndControlsButtonTooltips();
+    this.captionsToggleEnabled = true;
+    // If the CAPTIONS_TOGGLE_ENABLED_PREF pref is false then we will click
+    // the UI toggle to change the toggle to unchecked. This will call
+    // onToggleChange where this.captionsToggleEnabled will be updated
+    if (!Services.prefs.getBoolPref(CAPTIONS_TOGGLE_ENABLED_PREF, true)) {
+      document.querySelector("#subtitles-toggle").click();
+    }
+  },
+
+  disableSubtitlesButton() {
+    this.closedCaptionButton.disabled = true;
+
+    this.alignEndControlsButtonTooltips();
+  },
+
+  /**
+   * Sets focus state inline end tooltip for rightmost playback controls
+   */
+  alignEndControlsButtonTooltips() {
+    let audioBtn = document.getElementById("audio");
+    let width = window.outerWidth;
+
+    if (300 < width && width <= 400) {
+      audioBtn.classList.replace("center-tooltip", "inline-end-tooltip");
+    } else {
+      audioBtn.classList.replace("inline-end-tooltip", "center-tooltip");
+    }
+  },
+
+  /**
+   * Event handler for resizing the PiP Window
+   *
+   * @param {Event} event
+   *  Event context data object
+   */
+  onResize(event) {
+    this.toggleSubtitlesSettingsPanel({ forceHide: true });
+    this.resizeDebouncer.disarm();
+    this.resizeDebouncer.arm();
+  },
+
+  /**
+   * Event handler for user issued commands
+   *
+   * @param {Event} event
+   *  Event context data object
+   */
+  onCommand(event) {
+    this.closePipWindow({ reason: "shortcut" });
+  },
+
+  get controls() {
+    delete this.controls;
+    return (this.controls = document.getElementById("controls"));
+  },
+
+  get scrubber() {
+    delete this.scrubber;
+    return (this.scrubber = document.getElementById("scrubber"));
+  },
+
+  get timestamp() {
+    delete this.timestamp;
+    return (this.timestamp = document.getElementById("timestamp"));
+  },
+
+  get controlsBottom() {
+    delete this.controlsBottom;
+    return (this.controlsBottom = document.getElementById("controls-bottom"));
+  },
+
+  get seekBackward() {
+    delete this.seekBackward;
+    return (this.seekBackward = document.getElementById("seekBackward"));
+  },
+
+  get seekForward() {
+    delete this.seekForward;
+    return (this.seekForward = document.getElementById("seekForward"));
+  },
+
+  get closedCaptionButton() {
+    delete this.closedCaptionButton;
+    return (this.closedCaptionButton =
+      document.getElementById("closed-caption"));
+  },
+
+  get settingsPanel() {
+    delete this.settingsPanel;
+    return (this.settingsPanel = document.getElementById("settings"));
+  },
+
+  _isPlaying: false,
+  /**
+   * GET isPlaying returns true if the video is currently playing.
+   *
+   * SET isPlaying to true if the video is playing, false otherwise. This will
+   * update the internal state and displayed controls.
+   *
+   * @type {Boolean}
+   */
+  get isPlaying() {
+    return this._isPlaying;
+  },
+
+  set isPlaying(isPlaying) {
+    this._isPlaying = isPlaying;
+    this.controls.classList.toggle("playing", isPlaying);
+    let strId = isPlaying
+      ? `pictureinpicture-pause-btn`
+      : `pictureinpicture-play-btn`;
+    this.setupTooltip("playpause", strId);
+  },
+
+  _isMuted: false,
+  /**
+   * GET isMuted returns true if the video is currently muted.
+   *
+   * SET isMuted to true if the video is muted, false otherwise. This will
+   * update the internal state and displayed controls.
+   *
+   * @type {Boolean}
+   */
+  get isMuted() {
+    return this._isMuted;
+  },
+
+  set isMuted(isMuted) {
+    this._isMuted = isMuted;
+    this.controls.classList.toggle("muted", isMuted);
+    let strId = isMuted
+      ? `pictureinpicture-unmute-btn`
+      : `pictureinpicture-mute-btn`;
+    let shortcutId = isMuted ? "unMuteShortcut" : "muteShortcut";
+    this.setupTooltip("audio", strId, shortcutId);
+  },
+
+  /**
+   * GET isFullscreen returns true if the video is running in fullscreen mode
+   *
+   * @returns {boolean}
+   */
+  get isFullscreen() {
+    return document.fullscreenElement == document.body;
+  },
+
+  /**
+   * Used for recording telemetry in Picture-in-Picture.
+   *
+   * @param {string} type
+   *   The type of PiP event being recorded.
+   * @param {object} args
+   *   The data to pass to telemetry when the event is recorded.
+   */
+  recordEvent(type, args) {
+    Services.telemetry.recordEvent(
+      "pictureinpicture",
+      type,
+      "player",
+      this.id,
+      args
+    );
+  },
+
+  /**
+   * Send a message to PiPChild to adjust the subtitles position
+   */
+  showVideoControls() {
+    // offsetParent returns null when the element or any ancestor has display: none
+    // See https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement/offsetParent
+    this.actor.sendAsyncMessage("PictureInPicture:ShowVideoControls", {
+      isFullscreen: this.isFullscreen,
+      isVideoControlsShowing: true,
+      playerBottomControlsDOMRect: this.controlsBottom.getBoundingClientRect(),
+      isScrubberShowing: !!this.scrubber.offsetParent,
+    });
+  },
+
+  /**
+   * Makes the player controls visible.
+   *
+   * @param {Boolean} revealIndefinitely
+   *   If false, this will hide the controls again after
+   *   CONTROLS_FADE_TIMEOUT_MS milliseconds has passed. If true, the controls
+   *   will remain visible until revealControls is called again with
+   *   revealIndefinitely set to false.
+   */
+  revealControls(revealIndefinitely) {
+    clearTimeout(this.showingTimeout);
+    this.showingTimeout = null;
+
+    this.controls.setAttribute("showing", true);
+
+    if (!this.isFullscreen) {
+      // revealControls() is called everytime we hover over fullscreen pip window.
+      // Only communicate with pipchild when not in fullscreen mode for performance reasons.
+      this.showVideoControls();
+    }
+
+    if (!revealIndefinitely) {
+      this.showingTimeout = setTimeout(() => {
+        const isHoverOverControlItem = this.controls.querySelector(
+          ".control-item:hover"
+        );
+        if (this.isFullscreen && isHoverOverControlItem) {
+          return;
+        }
+        this.controls.removeAttribute("showing");
+
+        if (
+          !this.isFullscreen &&
+          !this.isCurrentHover &&
+          !this.controls.getAttribute("keying") &&
+          !this.controls.getAttribute("donthide")
+        ) {
+          this.actor.sendAsyncMessage("PictureInPicture:HideVideoControls", {
+            isFullscreen: false,
+            isVideoControlsShowing: false,
+            playerBottomControlsDOMRect: null,
+          });
+        }
+      }, CONTROLS_FADE_TIMEOUT_MS);
+    }
+  },
+
+  /**
+   * Given a width and height for a video, computes the minimum dimensions for
+   * the player window, and then sets them on the root element.
+   *
+   * This is currently only used on Linux GTK, where the OS doesn't already
+   * impose a minimum window size. For other platforms, this function is a
+   * no-op.
+   *
+   * @param {Number} width
+   *   The width of the video being played.
+   * @param {Number} height
+   *   The height of the video being played.
+   */
+  computeAndSetMinimumSize(width, height) {
+    if (!AppConstants.MOZ_WIDGET_GTK) {
+      return;
+    }
+
+    // Using inspection, these seem to be the right minimums for each dimension
+    // so that the controls don't get too crowded.
+    const MIN_WIDTH = 120;
+    const MIN_HEIGHT = 80;
+
+    let resultWidth = width;
+    let resultHeight = height;
+    let aspectRatio = width / height;
+
+    // Take the smaller of the two dimensions, and set it to the minimum.
+    // Then calculate the other dimension using the aspect ratio to get
+    // both minimums.
+    if (width < height) {
+      resultWidth = MIN_WIDTH;
+      resultHeight = Math.round(MIN_WIDTH / aspectRatio);
+    } else {
+      resultHeight = MIN_HEIGHT;
+      resultWidth = Math.round(MIN_HEIGHT * aspectRatio);
+    }
+
+    document.documentElement.style.minWidth = resultWidth + "px";
+    document.documentElement.style.minHeight = resultHeight + "px";
+  },
+};
diff --git a/toolkit/components/pictureinpicture/content/player.xhtml b/toolkit/components/pictureinpicture/content/player.xhtml
new file mode 100644
index 0000000000..82e4c8a0c7
--- /dev/null
+++ b/toolkit/components/pictureinpicture/content/player.xhtml
@@ -0,0 +1,117 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!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 xmlns="http://www.w3.org/1999/xhtml"
+      xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+      windowtype="Toolkit:PictureInPicture"
+      chromemargin="0,0,0,0"
+      >
+  <head>
+    <meta charset="utf-8"/>
+    <link rel="stylesheet" href="chrome://global/skin/pictureinpicture/player.css"/>
+    <link rel="localization" href="toolkit/pictureinpicture/pictureinpicture.ftl"/>
+    <link rel="localization" href="browser/browserSets.ftl"/>
+    <script src="chrome://global/content/pictureinpicture/player.js"></script>
+    <title data-l10n-id="pictureinpicture-player-title"></title>
+  </head>
+
+  <body>
+    <xul:commandset>
+      <xul:command id="View:PictureInPicture" oncommand="Player.onCommand(event);"/>
+      <xul:command id="View:Fullscreen" oncommand="Player.fullscreenModeToggle(event);"/>
+    </xul:commandset>
+
+    <xul:keyset>
+      <xul:key id="closeShortcut" key="W" modifiers="accel"/>
+      <xul:key id="muteShortcut" key="↓" modifiers="accel"/>
+      <xul:key id="unMuteShortcut" key="↑" modifiers="accel"/>
+#ifndef XP_MACOSX
+      <xul:key data-l10n-id="picture-in-picture-toggle-shortcut" command="View:PictureInPicture" modifiers="accel,shift"/>
+      <xul:key data-l10n-id="picture-in-picture-toggle-shortcut-alt" command="View:PictureInPicture" modifiers="accel,shift"/>
+#else
+      <xul:key data-l10n-id="picture-in-picture-toggle-shortcut-mac" command="View:PictureInPicture" modifiers="accel,alt,shift"/>
+      <xul:key data-l10n-id="picture-in-picture-toggle-shortcut-mac-alt" command="View:PictureInPicture" modifiers="accel,alt,shift"/>
+#endif
+      <xul:key id="fullscreenToggleShortcut" data-l10n-id="pictureinpicture-toggle-fullscreen-shortcut" command="View:Fullscreen"/>
+    </xul:keyset>
+
+    <div class="player-holder">
+      <xul:browser type="content" primary="true" remote="true" remoteType="web" id="browser" tabindex="-1"></xul:browser>
+    </div>
+    <div id="controls" dir="ltr">
+      <button id="close"
+      class="control-item control-button tooltip-under-controls" data-l10n-attrs="tooltip"
+#ifdef XP_MACOSX
+      mac="true"
+      tabindex="8"
+#else
+      tabindex="9"
+#endif
+      />
+      <button id="unpip"
+      class="control-item control-button tooltip-under-controls" data-l10n-id="pictureinpicture-unpip-btn" data-l10n-attrs="tooltip"
+#ifdef XP_MACOSX
+      mac="true"
+      tabindex="9"
+#else
+      tabindex="8"
+#endif
+      />
+    <div id="controls-bottom-gradient" class="control-item"></div>
+    <div id="controls-bottom">
+      <div class="controls-bottom-upper">
+          <div class="scrubber-no-drag">
+            <input id="scrubber" class="control-item" min="0" max="1" step=".001" type="range" tabindex="10" hidden="true"/>
+          </div>
+      </div>
+      <div class="controls-bottom-lower">
+        <div class="start-controls">
+          <div id="timestamp" class="control-item" hidden="true"></div>
+        </div>
+        <div class="center-controls">
+          <button id="seekBackward" class="control-item control-button tooltip-over-controls center-tooltip" hidden="true" data-l10n-id="pictureinpicture-seekbackward-btn" data-l10n-attrs="tooltip" tabindex="11"></button>
+          <button id="playpause" class="control-item control-button tooltip-over-controls center-tooltip" tabindex="1"
+                  data-l10n-id="pictureinpicture-pause-btn" data-l10n-attrs="tooltip"/>
+          <button id="seekForward" class="control-item control-button tooltip-over-controls center-tooltip" hidden="true" data-l10n-id="pictureinpicture-seekforward-btn" data-l10n-attrs="tooltip" tabindex="2"></button>
+        </div>
+        <div class="end-controls">
+          <button id="audio" class="control-item control-button tooltip-over-controls center-tooltip" hidden="true" data-l10n-attrs="tooltip" tabindex="3"/>
+          <button id="closed-caption" class="control-item control-button tooltip-over-controls center-tooltip closed-caption" hidden="true" disabled="true" data-l10n-id="pictureinpicture-subtitles-btn" data-l10n-attrs="tooltip" tabindex="4"></button>
+          <div id="settings" class="hide panel">
+            <fieldset class="box panel-fieldset">
+              <legend class="a11y-only panel-legend" data-l10n-id="pictureinpicture-subtitles-panel-accessible"></legend>
+              <div class="subtitle-grid">
+                <label id="subtitles-toggle-label" data-l10n-id="pictureinpicture-subtitles-label" class="bold" for="subtitles-toggle"></label>
+                <label class="switch">
+                  <input id="subtitles-toggle" type="checkbox" tabindex="5" checked=""/>
+                  <span class="slider" role="presentation"></span>
+                </label>
+              </div>
+              <div class="grey-line"></div>
+              <fieldset class="font-size-selection panel-fieldset">
+                <legend data-l10n-id="pictureinpicture-font-size-label" class="bold panel-legend"></legend>
+                <div id="font-size-selection-radio-small" class="font-size-selection-radio">
+                  <input id="small" type="radio" name="cc-size" tabindex="6"/>
+                  <label data-l10n-id="pictureinpicture-font-size-small" for="small"></label>
+                </div>
+                <div id="font-size-selection-radio-medium" class="font-size-selection-radio">
+                  <input id="medium" type="radio" name="cc-size" tabindex="6"/>
+                  <label data-l10n-id="pictureinpicture-font-size-medium" for="medium"></label>
+                </div>
+                <div id="font-size-selection-radio-large" class="font-size-selection-radio">
+                  <input id="large" type="radio" name="cc-size" tabindex="6"/>
+                  <label data-l10n-id="pictureinpicture-font-size-large" for="large"></label>
+                </div>
+              </fieldset>
+            </fieldset>
+            <div class="arrow"></div>
+          </div>
+          <button id="fullscreen" class="control-item control-button tooltip-over-controls inline-end-tooltip" hidden="true" data-l10n-attrs="tooltip" tabindex="7"></button>
+        </div>
+      </div>
+    </div>
+  </div>
+  </body>
+</html>
diff --git a/toolkit/components/pictureinpicture/docs/PiP-diagram.svg b/toolkit/components/pictureinpicture/docs/PiP-diagram.svg
new file mode 100644
index 0000000000..391cc7728a
--- /dev/null
+++ b/toolkit/components/pictureinpicture/docs/PiP-diagram.svg
@@ -0,0 +1,4 @@
+<!-- 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/. -->
+<svg xmlns="http://www.w3.org/2000/svg" style="background-color:#fff" width="1241" height="1169" viewBox="-0.5 -0.5 1241 1169"><path fill="#ffe6cc" stroke="#d79b00" pointer-events="all" d="M0 860h390v280H0z"/><path d="M290 1070v20h761l-.01 58.86" fill="none" stroke="#000" stroke-width="3" stroke-miterlimit="10" pointer-events="stroke"/><path d="M1050.99 1155.61l-4.5-9 4.5 2.25 4.5-2.25z" stroke="#000" stroke-width="3" stroke-miterlimit="10" pointer-events="all"/><path fill="none" stroke="#000" pointer-events="all" d="M80 960h210v110H80z"/><path d="M0 0h480v340H0z" fill="#ffe6cc" stroke="#d79b00" stroke-miterlimit="10" pointer-events="all"/><circle cx="415" cy="15" fill="transparent" stroke="#d79b00" pointer-events="all" r="10"/><circle cx="440" cy="15" fill="transparent" stroke="#d79b00" pointer-events="all" r="10"/><circle cx="465" cy="15" fill="transparent" stroke="#008cff" pointer-events="all" r="10"/><path d="M0 40h30V15c0-2.76 2.24-5 5-5h135c2.76 0 5 2.24 5 5v25h305M0 110h480M100 60c0-2.76 2.24-5 5-5h360c2.76 0 5 2.24 5 5v25c0 2.76-2.24 5-5 5H105c-2.76 0-5-2.24-5-5z" fill="none" stroke="#c4c4c4" stroke-miterlimit="10" pointer-events="all"/><path d="M37 17h11l4 4v14H37z" fill="none" stroke="#c4c4c4" stroke-miterlimit="10" pointer-events="all"/><path d="M48 17v4l4 1" fill="none" stroke="#c4c4c4" stroke-miterlimit="10" pointer-events="all"/><path d="M107 64h11l4 4v14h-15z" fill="none" stroke="#c4c4c4" stroke-width="2" stroke-miterlimit="10" pointer-events="all"/><path d="M118 64v4l4 1" fill="none" stroke="#c4c4c4" stroke-miterlimit="10" pointer-events="all"/><path d="M12 74l10-10v6h10v8H22v6zM62 74L52 64v6H42v8h10v6zM87.6 77.3a6 6 0 01-8.22 2.06c-2.84-1.69-3.77-5.36-2.09-8.21 1.69-2.84 5.36-3.79 8.21-2.11l-1.6 1.46 7.9 1.8-1.8-7.5-1.7 1.6a9.816 9.816 0 00-10.91-.53 9.799 9.799 0 00-4.62 9.89c.6 3.93 3.53 7.1 7.39 8.03 3.87.93 7.91-.57 10.24-3.79z" fill="#c4c4c4" stroke="#c4c4c4" stroke-width="2" stroke-miterlimit="10" pointer-events="all"/><switch transform="translate(-.5 -.5)"><foreignObject style="overflow:visible;text-align:left" pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility"><div xmlns="http://www.w3.org/1999/xhtml" style="display:flex;align-items:unsafe center;justify-content:unsafe flex-start;width:1px;height:1px;padding-top:25px;margin-left:62px"><div style="box-sizing:border-box;font-size:0;text-align:left"><div style="display:inline-block;font-size:17px;font-family:Helvetica;color:#666;line-height:1.2;pointer-events:all;white-space:nowrap"><div>Twitch</div></div></div></div></foreignObject><text x="62" y="30" fill="#666" font-family="Helvetica" font-size="17">Twitch</text></switch><switch transform="translate(-.5 -.5)"><foreignObject style="overflow:visible;text-align:left" pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility"><div xmlns="http://www.w3.org/1999/xhtml" style="display:flex;align-items:unsafe center;justify-content:unsafe flex-start;width:1px;height:1px;padding-top:73px;margin-left:132px"><div style="box-sizing:border-box;font-size:0;text-align:left"><div style="display:inline-block;font-size:17px;font-family:Helvetica;color:#666;line-height:1.2;pointer-events:all;white-space:nowrap"><div>https://www.twitch.tv</div></div></div></div></foreignObject><text x="132" y="78" fill="#666" font-family="Helvetica" font-size="17">https://www.twitch.tv</text></switch><path fill="#dae8fc" stroke="#6c8ebf" pointer-events="all" d="M0 110h480v230H0z"/><path d="M78.08 315c-3.08 0-5.58-2.3-5.58-5.14V140.14c0-2.84 2.5-5.14 5.58-5.14h323.84c3.08 0 5.58 2.3 5.58 5.14v169.72c0 2.84-2.5 5.14-5.58 5.14z" fill="#f66" pointer-events="all"/><path d="M221.65 267.98l44.66-23.6-44.66-23.44zm-39.3 24.5c-4.07 0-7.3-3.53-7.3-6.75v-82.85c0-3.8 3.8-6.79 7.29-6.79h114.89c5.16 0 7.72 3.99 7.72 6.76v82.78c0 3.57-3.4 6.85-7.44 6.85zM75.29 176.14v133.72c0 1.42 1.25 2.57 2.79 2.57h323.84c1.54 0 2.79-1.15 2.79-2.57V176.14z" fill-opacity=".5" fill="#fff" pointer-events="all"/><switch transform="translate(-.5 -.5)"><foreignObject style="overflow:visible;text-align:left" pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility"><div xmlns="http://www.w3.org/1999/xhtml" style="display:flex;align-items:unsafe flex-start;justify-content:unsafe center;width:1px;height:1px;padding-top:136px;margin-left:240px"><div style="box-sizing:border-box;font-size:0;text-align:center"><div style="display:inline-block;font-size:12px;font-family:Helvetica;color:#fff;line-height:1.2;pointer-events:all;white-space:nowrap">Video</div></div></div></foreignObject><text x="240" y="148" fill="#FFF" font-family="Helvetica" font-size="12" text-anchor="middle">Video</text></switch><path fill="#08f" stroke="#000" pointer-events="all" d="M387.5 225h20v20h-20z"/><path fill="#dae8fc" stroke="#6c8ebf" pointer-events="all" d="M0 420h710v380H0z"/><path fill="none" pointer-events="all" d="M0 420h200v30H0z"/><switch transform="translate(-.5 -.5)"><foreignObject style="overflow:visible;text-align:left" pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility"><div xmlns="http://www.w3.org/1999/xhtml" style="display:flex;align-items:unsafe flex-start;justify-content:unsafe flex-start;width:1px;height:1px;padding-top:423px;margin-left:2px"><div style="box-sizing:border-box;font-size:0;text-align:left"><div style="display:inline-block;font-size:12px;font-family:Helvetica;color:#000;line-height:1.2;pointer-events:all;white-space:nowrap"><div>Content process hosting the video</div><div><br/></div></div></div></div></foreignObject><text x="2" y="435" font-family="Helvetica" font-size="12">Content process hosting the video</text></switch><path fill="#fff" stroke="#000" pointer-events="all" d="M230 450h180v80H230z"/><switch transform="translate(-.5 -.5)"><foreignObject style="overflow:visible;text-align:left" pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility"><div xmlns="http://www.w3.org/1999/xhtml" style="display:flex;align-items:unsafe center;justify-content:unsafe center;width:178px;height:1px;padding-top:490px;margin-left:231px"><div style="box-sizing:border-box;font-size:0;text-align:center"><div style="display:inline-block;font-size:12px;font-family:Helvetica;color:#000;line-height:1.2;pointer-events:all;white-space:normal;word-wrap:normal">videocontrols.js</div></div></div></foreignObject><text x="320" y="494" font-family="Helvetica" font-size="12" text-anchor="middle">videocontrols.js</text></switch><path d="M407.5 235h10q10 0 10 10v92.5q0 10-10 10H220q-10 0-10 10V480q0 10 10 10h10M175 630v69.9" fill="none" stroke="#000" stroke-width="3" stroke-miterlimit="10" pointer-events="stroke"/><path d="M175 706.65l-4.5-9 4.5 2.25 4.5-2.25z" stroke="#000" stroke-width="3" stroke-miterlimit="10" pointer-events="all"/><switch transform="translate(-.5 -.5)"><foreignObject style="overflow:visible;text-align:left" pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility"><div xmlns="http://www.w3.org/1999/xhtml" style="display:flex;align-items:unsafe center;justify-content:unsafe center;width:1px;height:1px;padding-top:670px;margin-left:175px"><div style="box-sizing:border-box;font-size:0;text-align:center"><div style="display:inline-block;font-size:11px;font-family:Helvetica;color:#000;line-height:1.2;pointer-events:all;background-color:#fff;white-space:nowrap">MozTogglePictureInPicture chrome event</div></div></div></foreignObject><text x="175" y="673" font-family="Helvetica" font-size="11" text-anchor="middle">MozTogglePictureInPicture chrome event</text></switch><path d="M50 585H30v245h195v119.9" fill="none" stroke="#000" stroke-width="3" stroke-miterlimit="10" pointer-events="stroke"/><path d="M225 956.65l-4.5-9 4.5 2.25 4.5-2.25z" stroke="#000" stroke-width="3" stroke-miterlimit="10" pointer-events="all"/><switch transform="translate(-.5 -.5)"><foreignObject style="overflow:visible;text-align:left" pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility"><div xmlns="http://www.w3.org/1999/xhtml" style="display:flex;align-items:unsafe center;justify-content:unsafe center;width:1px;height:1px;padding-top:831px;margin-left:91px"><div style="box-sizing:border-box;font-size:0;text-align:center"><div style="display:inline-block;font-size:12px;font-family:Helvetica;color:#000;line-height:1.2;pointer-events:all;background-color:#fff;white-space:nowrap">JSWindowActor messaging</div></div></div></foreignObject><text x="91" y="834" font-family="Helvetica" font-size="12" text-anchor="middle">JSWindowActor messaging</text></switch><path fill="#fff" stroke="#000" pointer-events="all" d="M50 540h250v90H50z"/><switch transform="translate(-.5 -.5)"><foreignObject style="overflow:visible;text-align:left" pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility"><div xmlns="http://www.w3.org/1999/xhtml" style="display:flex;align-items:unsafe center;justify-content:unsafe center;width:248px;height:1px;padding-top:585px;margin-left:51px"><div style="box-sizing:border-box;font-size:0;text-align:center"><div style="display:inline-block;font-size:12px;font-family:Helvetica;color:#000;line-height:1.2;pointer-events:all;white-space:normal;word-wrap:normal">PictureInPictureToggleChild</div></div></div></foreignObject><text x="175" y="589" font-family="Helvetica" font-size="12" text-anchor="middle">PictureInPictureToggleChild</text></switch><path d="M300 750h20v290h-39.9" fill="none" stroke="#000" stroke-width="3" stroke-miterlimit="10" pointer-events="stroke"/><path d="M273.35 1040l9-4.5-2.25 4.5 2.25 4.5z" stroke="#000" stroke-width="3" stroke-miterlimit="10" pointer-events="all"/><switch transform="translate(-.5 -.5)"><foreignObject style="overflow:visible;text-align:left" pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility"><div xmlns="http://www.w3.org/1999/xhtml" style="display:flex;align-items:unsafe center;justify-content:unsafe center;width:1px;height:1px;padding-top:833px;margin-left:319px"><div style="box-sizing:border-box;font-size:0;text-align:center"><div style="display:inline-block;font-size:12px;font-family:Helvetica;color:#000;line-height:1.2;pointer-events:all;background-color:#fff;white-space:nowrap">JSWindowActor messaging</div></div></div></foreignObject><text x="319" y="836" font-family="Helvetica" font-size="12" text-anchor="middle">JSWindowActor messaging</text></switch><path fill="#fff" stroke="#000" pointer-events="all" d="M50 710h250v80H50z"/><switch transform="translate(-.5 -.5)"><foreignObject style="overflow:visible;text-align:left" pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility"><div xmlns="http://www.w3.org/1999/xhtml" style="display:flex;align-items:unsafe center;justify-content:unsafe center;width:248px;height:1px;padding-top:750px;margin-left:51px"><div style="box-sizing:border-box;font-size:0;text-align:center"><div style="display:inline-block;font-size:12px;font-family:Helvetica;color:#000;line-height:1.2;pointer-events:all;white-space:normal;word-wrap:normal"><div>PictureInPictureLauncherChild<br/></div></div></div></div></foreignObject><text x="175" y="754" font-family="Helvetica" font-size="12" text-anchor="middle">PictureInPictureLauncherChild</text></switch><path fill="#fff" stroke="#000" pointer-events="all" d="M430 680h250v80H430z"/><switch transform="translate(-.5 -.5)"><foreignObject style="overflow:visible;text-align:left" pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility"><div xmlns="http://www.w3.org/1999/xhtml" style="display:flex;align-items:unsafe center;justify-content:unsafe center;width:248px;height:1px;padding-top:720px;margin-left:431px"><div style="box-sizing:border-box;font-size:0;text-align:center"><div style="display:inline-block;font-size:12px;font-family:Helvetica;color:#000;line-height:1.2;pointer-events:all;white-space:normal;word-wrap:normal">PictureInPictureChild for player &lt;video&gt;</div></div></div></foreignObject><text x="555" y="724" font-family="Helvetica" font-size="12" text-anchor="middle">PictureInPictureChild for player &lt;video&gt;</text></switch><path fill="#fff" stroke="#000" pointer-events="all" d="M90 960h180v40H90z"/><switch transform="translate(-.5 -.5)"><foreignObject style="overflow:visible;text-align:left" pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility"><div xmlns="http://www.w3.org/1999/xhtml" style="display:flex;align-items:unsafe center;justify-content:unsafe center;width:178px;height:1px;padding-top:980px;margin-left:91px"><div style="box-sizing:border-box;font-size:0;text-align:center"><div style="display:inline-block;font-size:12px;font-family:Helvetica;color:#000;line-height:1.2;pointer-events:all;white-space:normal;word-wrap:normal">PictureInPictureToggleParent</div></div></div></foreignObject><text x="180" y="984" font-family="Helvetica" font-size="12" text-anchor="middle">PictureInPictureToggleParent</text></switch><path fill="#fff" stroke="#000" pointer-events="all" d="M90 1020h180v40H90z"/><switch transform="translate(-.5 -.5)"><foreignObject style="overflow:visible;text-align:left" pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility"><div xmlns="http://www.w3.org/1999/xhtml" style="display:flex;align-items:unsafe center;justify-content:unsafe center;width:178px;height:1px;padding-top:1040px;margin-left:91px"><div style="box-sizing:border-box;font-size:0;text-align:center"><div style="display:inline-block;font-size:12px;font-family:Helvetica;color:#000;line-height:1.2;pointer-events:all;white-space:normal;word-wrap:normal">PictureInPictureLauncherParent</div></div></div></foreignObject><text x="180" y="1044" font-family="Helvetica" font-size="12" text-anchor="middle">PictureInPictureLauncherParent</text></switch><path fill="none" pointer-events="all" d="M80 930h120v30H80z"/><switch transform="translate(-.5 -.5)"><foreignObject style="overflow:visible;text-align:left" pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility"><div xmlns="http://www.w3.org/1999/xhtml" style="display:flex;align-items:unsafe flex-start;justify-content:unsafe flex-start;width:1px;height:1px;padding-top:933px;margin-left:82px"><div style="box-sizing:border-box;font-size:0;text-align:left"><div style="display:inline-block;font-size:12px;font-family:Helvetica;color:#000;line-height:1.2;pointer-events:all;white-space:nowrap"><div>PictureInPicture.jsm</div><div><br/></div></div></div></div></foreignObject><text x="82" y="945" font-family="Helvetica" font-size="12">PictureInPicture.jsm</text></switch><path fill="#ffe6cc" stroke="#d79b00" pointer-events="all" d="M830 640h410v520H830z"/><path fill="none" pointer-events="all" d="M0 860h100v20H0z"/><switch transform="translate(-.5 -.5)"><foreignObject style="overflow:visible;text-align:left" pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility"><div xmlns="http://www.w3.org/1999/xhtml" style="display:flex;align-items:unsafe flex-start;justify-content:unsafe flex-start;width:1px;height:1px;padding-top:863px;margin-left:2px"><div style="box-sizing:border-box;font-size:0;text-align:left"><div style="display:inline-block;font-size:12px;font-family:Helvetica;color:#000;line-height:1.2;pointer-events:all;white-space:nowrap">Parent process</div></div></div></foreignObject><text x="2" y="875" font-family="Helvetica" font-size="12">Parent process</text></switch><path fill="none" pointer-events="all" d="M840 650h250v20H840z"/><switch transform="translate(-.5 -.5)"><foreignObject style="overflow:visible;text-align:left" pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility"><div xmlns="http://www.w3.org/1999/xhtml" style="display:flex;align-items:unsafe flex-start;justify-content:unsafe flex-start;width:1px;height:1px;padding-top:653px;margin-left:842px"><div style="box-sizing:border-box;font-size:0;text-align:left"><div style="display:inline-block;font-size:12px;font-family:Helvetica;color:#000;line-height:1.2;pointer-events:all;white-space:nowrap">player.xhtml / player.js - alwaysontop window</div></div></div></foreignObject><text x="842" y="665" font-family="Helvetica" font-size="12">player.xhtml / player.js - alwaysontop wi...</text></switch><path fill="#dae8fc" stroke="#6c8ebf" pointer-events="all" d="M840 920h390v230H840z"/><path fill="none" pointer-events="all" d="M850 920h340v30H850z"/><switch transform="translate(-.5 -.5)"><foreignObject style="overflow:visible;text-align:left" pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility"><div xmlns="http://www.w3.org/1999/xhtml" style="display:flex;align-items:unsafe flex-start;justify-content:unsafe flex-start;width:1px;height:1px;padding-top:923px;margin-left:852px"><div style="box-sizing:border-box;font-size:0;text-align:left"><div style="display:inline-block;font-size:12px;font-family:Helvetica;color:#000;line-height:1.2;pointer-events:all;white-space:nowrap"><div>remote &lt;xul:browser&gt; running in the same content process as</div><div>original video</div></div></div></div></foreignObject><text x="852" y="935" font-family="Helvetica" font-size="12">remote &lt;xul:browser&gt; running in the same content process...</text></switch><path d="M865.58 1125c-1.48 0-2.9-.47-3.94-1.3-1.05-.83-1.64-1.95-1.64-3.13V974.43c0-1.18.59-2.3 1.64-3.13 1.04-.83 2.46-1.3 3.94-1.3h323.84c1.48 0 2.9.47 3.94 1.3 1.05.83 1.64 1.95 1.64 3.13v146.14c0 1.18-.59 2.3-1.64 3.13-1.04.83-2.46 1.3-3.94 1.3z" fill="#f66" pointer-events="all"/><path d="M1009.15 1084.51l44.66-20.32-44.66-20.19zm-39.3 21.1c-4.07 0-7.3-3.04-7.3-5.82v-71.34c0-3.27 3.8-5.84 7.29-5.84h114.89c5.16 0 7.72 3.43 7.72 5.82v71.28c0 3.08-3.4 5.9-7.44 5.9zm-107.06-100.18v115.14c0 .59.3 1.15.82 1.57.52.41 1.23.65 1.97.65h323.84c.74 0 1.45-.24 1.97-.65.52-.42.82-.98.82-1.57v-115.14z" fill-opacity=".5" fill="#fff" pointer-events="all"/><switch transform="translate(-.5 -.5)"><foreignObject style="overflow:visible;text-align:left" pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility"><div xmlns="http://www.w3.org/1999/xhtml" style="display:flex;align-items:unsafe flex-start;justify-content:unsafe center;width:1px;height:1px;padding-top:971px;margin-left:1028px"><div style="box-sizing:border-box;font-size:0;text-align:center"><div style="display:inline-block;font-size:12px;font-family:Helvetica;color:#fff;line-height:1.2;pointer-events:all;white-space:nowrap">Player video</div></div></div></foreignObject><text x="1028" y="983" fill="#FFF" font-family="Helvetica" font-size="12" text-anchor="middle">Player video</text></switch><path d="M915 720H690.1" fill="none" stroke="#000" stroke-width="3" stroke-miterlimit="10" pointer-events="stroke"/><path d="M683.35 720l9-4.5-2.25 4.5 2.25 4.5z" stroke="#000" stroke-width="3" stroke-miterlimit="10" pointer-events="all"/><switch transform="translate(-.5 -.5)"><foreignObject style="overflow:visible;text-align:left" pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility"><div xmlns="http://www.w3.org/1999/xhtml" style="display:flex;align-items:unsafe center;justify-content:unsafe center;width:1px;height:1px;padding-top:721px;margin-left:771px"><div style="box-sizing:border-box;font-size:0;text-align:center"><div style="display:inline-block;font-size:12px;font-family:Helvetica;color:#000;line-height:1.2;pointer-events:all;background-color:#fff;white-space:nowrap"><div>JSWindowActor</div><div>Messaging<br/></div></div></div></div></foreignObject><text x="771" y="724" font-family="Helvetica" font-size="12" text-anchor="middle">JSWindowActor...</text></switch><path fill="#fff" stroke="#000" pointer-events="all" d="M915 700h180v40H915z"/><switch transform="translate(-.5 -.5)"><foreignObject style="overflow:visible;text-align:left" pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility"><div xmlns="http://www.w3.org/1999/xhtml" style="display:flex;align-items:unsafe center;justify-content:unsafe center;width:178px;height:1px;padding-top:720px;margin-left:916px"><div style="box-sizing:border-box;font-size:0;text-align:center"><div style="display:inline-block;font-size:12px;font-family:Helvetica;color:#000;line-height:1.2;pointer-events:all;white-space:normal;word-wrap:normal">PictureInPictureParent</div></div></div></foreignObject><text x="1005" y="724" font-family="Helvetica" font-size="12" text-anchor="middle">PictureInPictureParent</text></switch><path d="M555 760h215v287.5h79.9" fill="none" stroke="#000" stroke-width="3" stroke-miterlimit="10" pointer-events="stroke"/><path d="M856.65 1047.5l-9 4.5 2.25-4.5-2.25-4.5z" stroke="#000" stroke-width="3" stroke-miterlimit="10" pointer-events="all"/><path d="M185 1070h0" fill="none" stroke="#000" stroke-miterlimit="10" pointer-events="stroke"/><path d="M185 1070h0z" stroke="#000" stroke-miterlimit="10" pointer-events="all"/><path fill="none" pointer-events="all" d="M570 1070h40v20h-40z"/><switch transform="translate(-.5 -.5)"><foreignObject style="overflow:visible;text-align:left" pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility"><div xmlns="http://www.w3.org/1999/xhtml" style="display:flex;align-items:unsafe center;justify-content:unsafe center;width:38px;height:1px;padding-top:1080px;margin-left:571px"><div style="box-sizing:border-box;font-size:0;text-align:center"><div style="display:inline-block;font-size:12px;font-family:Helvetica;color:#000;line-height:1.2;pointer-events:all;white-space:normal;word-wrap:normal">Services.ww.openWindow</div></div></div></foreignObject><text x="590" y="1084" font-family="Helvetica" font-size="12" text-anchor="middle">Servic...</text></switch></svg>
\ No newline at end of file
diff --git a/toolkit/components/pictureinpicture/docs/index.rst b/toolkit/components/pictureinpicture/docs/index.rst
new file mode 100644
index 0000000000..a5e255d4e3
--- /dev/null
+++ b/toolkit/components/pictureinpicture/docs/index.rst
@@ -0,0 +1,385 @@
+.. _components/pictureinpicture:
+
+==================
+Picture-in-Picture
+==================
+
+This component makes it possible for a ``<video>`` element on a web page to be played within
+an always-on-top video player.
+
+This documentation covers the architecture and inner workings of both the mechanism that
+displays the ``<video>`` in the always-on-top video player, as well as the mechanism that
+displays the Picture-in-Picture toggle that overlays ``<video>`` elements, which is the primary
+method for launching the feature.
+
+
+High-level overview
+===================
+
+The following diagram tries to illustrate the subcomponents, and how they interact with one another.
+
+.. image:: PiP-diagram.svg
+
+Let's suppose that the user has loaded a document with a ``<video>`` in it, and they decide to open
+it in a Picture-in-Picture window. What happens?
+
+First the ``PictureInPictureToggleChild`` component notices when ``<video>`` elements are added to the
+DOM, and monitors the mouse as it moves around the document. Once the mouse intersects a ``<video>``,
+``PictureInPictureToggleChild`` causes the Picture-in-Picture toggle to appear on that element.
+
+If the user clicks on that toggle, then the ``PictureInPictureToggleChild`` dispatches a chrome-only
+``MozTogglePictureInPicture`` event on the video, which is handled by the ``PictureInPictureLauncherChild`` actor
+for that document. The reason for the indirection via the event is that the media context menu can also
+trigger Picture-in-Picture by dispatching the same event on the video. Upon handling the event, the
+``PictureInPictureLauncherChild`` actor then sends a ``PictureInPicture:Request`` message to the parent process.
+The parent process opens up the always-on-top player window, with a remote ``<xul:browser>`` that runs in
+the same content process as the original ``<video>``. The parent then sends a message to the player
+window's remote ``<xul:browser>`` loaded in the player window. A ``PictureInPictureChild`` actor
+is instantiated for the empty document loaded inside of the player window browser. This
+``PictureInPictureChild`` actor constructs its own ``<video>`` element, and then tells Gecko to clone the
+frames from the original ``<video>`` to the newly created ``<video>``.
+
+At this point, the video is displaying in the Picture-in-Picture player window.
+
+Next, we'll discuss the individual subcomponents, and how they operate at a more detailed level.
+
+
+The Picture-in-Picture toggle
+=============================
+
+One of the primary challenges faced when developing this feature was the fact that, in practice, mouse
+events tend not to reach ``<video>`` elements. This is usually because the ``<video>`` element is
+contained within a hierarchy of other DOM elements that are capturing and handling any events that
+come down. This often occurs on sites that construct their own video controls. This is why we cannot
+simply use a ``mouseover`` event handler on the ``<video>`` UAWidget - on sites that do the event
+capturing, we'll never receive those events and the toggle will not be accessible.
+
+Other times, the problem is that the video is overlaid with a semi or fully transparent element
+which captures any mouse events that would normally be dispatched to the underlying ``<video>``.
+This can occur, for example, on sites that want to display an overlay when the video is paused.
+
+To work around this problem, the `PictureInPictureToggleChild` actor class samples the latest
+``mousemove`` event every ``MOUSEMOVE_PROCESSING_DELAY_MS`` milliseconds, and then calls
+``nsIDOMWindowUtils.nodesFromRect`` with the ``aOnlyVisible`` argument to get the full
+list of visible nodes that exist underneath a 1x1 rect positioned at the mouse cursor.
+
+If a ``<video>`` is in that list, then we reach into its shadow root, and update some
+attributes to tell it to maybe show the toggle.
+
+The underlying ``UAWidget`` for the video is defined in ``videocontrols.js``, and ultimately
+chooses whether or not to display the toggle based on the following heuristics:
+
+1. Is the video less than 45 seconds?
+2. Is either the width or the height of the video less than 160px?
+3. Is the video silent?
+
+If any of the above is true, the underlying ``UAWidget`` will hide the toggle, since it's
+unlikely that the user will want to pop the video out into an always-on-top player window.
+
+
+Video registration
+==================
+
+Sampling the latest ``mousemove`` event every ``MOUSEMOVE_PROCESSING_DELAY_MS`` is not free,
+computationally speaking, so we only do this if there are one or more ``<video>`` elements
+visible on the page. We use an ``IntersectionObserver`` to notice when there is a ``<video>``
+within the viewport, and if there are 1 or more ``<video>`` elements visible, then we start
+sampling the ``mousemove`` event.
+
+Videos are added to the ``IntersectionObserver`` when they are added to the DOM by listening
+for the ``UAWidgetSetupOrChange`` event. This is considered being "registered".
+
+
+``docState``
+============
+
+``PictureInPictureChild.sys.mjs`` contains a ``WeakMap`` mapping ``document``'s to various information
+that ``PictureInPictureToggleChild`` wants to retain for the lifetime of that ``document``. For
+example, whether or not we're in the midst of handling the user clicking down on their pointer
+device. Any state that needs to be remembered should be added to the ``docState`` ``WeakMap``.
+
+
+Clicking on the toggle
+======================
+
+If the user clicks on the Picture-in-Picture toggle, we don't want the underlying webpage to
+know that this happened, since this could result in unexpected behaviour, like a page
+navigation (for example, if the ``<video>`` is a long-running advertisement that navigates
+upon click).
+
+To accomplish this, we listen for all events fired on a mouse click on the root window during
+the capturing phase. This allows us to handle the events before they are dispatched to content.
+
+The first event that is fired, ``pointerdown``, is captured, and we check the ``docState`` to see
+whether or not we're showing a toggle on any videos. If so, we check the coordinates of that
+toggle against the coordinates of the ``pointerdown`` event to determine if the user is clicking
+on the toggle. If so, we set a flag in the ``docState`` so that any subsequent events from the
+click (like ``mousedown``, ``mouseup``, ``pointerup``, ``click``) are captured and suppressed.
+If the ``pointerdown`` event didn't occur within a toggle, we let the events pass through as
+normal.
+
+If we determine that the click has occurred on the toggle, a ``MozTogglePictureInPicture`` event
+is dispatched on the underlying ``<video>``. This event is handled by the separate
+``PictureInPictureLauncherChild`` class.
+
+PictureInPictureLauncherChild
+=============================
+
+A small actor class whose only responsibility is to tell the parent process to open an always-on-top-window by sending a ``PictureInPicture:Request`` message to its parent actor.
+
+Currently, this only occurs when a chrome-only ``MozTogglePictureInPicture`` event is dispatched by the ``PictureInPictureToggleChild`` when the user clicks the Picture-in-Picture toggle button
+or uses the context-menu.
+
+PictureInPictureChild
+=====================
+
+The ``PictureInPictureChild`` actor class will run in a content process containing a video, and is instantiated when the player window's `player.js` script runs its initialization. A ``PictureInPictureChild`` maps an individual ``<video>``
+to a player window instance. It creates an always-on-top window, and sets up a new ``<video>`` inside of this window to clone frames from another ``<video>``
+(which will be in the same process, and have its own ``PictureInPictureChild``). Creating this window also causes the new ``PictureInPictureChild`` to be created.
+This instance will monitor the originating ``<video>`` for changes, and to receive commands from the player window if the user wants to control the ``<video>``.
+
+PictureInPicture.sys.mjs
+========================
+
+This module runs in the parent process, and is also the scope where all ``PictureInPictureParent`` instances reside. ``PictureInPicture.sys.mjs``'s job is to send and receive messages from ``PictureInPictureChild`` instances, and to react appropriately.
+
+Critically, ``PictureInPicture.sys.mjs`` is responsible for opening up the always-on-top player window, and passing the relevant information about the ``<video>`` to be displayed to it.
+
+
+The Picture-in-Picture player window
+====================================
+
+The Picture-in-Picture player window is a chrome-privileged window that loads an XHTML document. That document contains a remote ``<browser>`` element which is repurposed during window initialization to load in the same content process as the originating ``<video>``.
+
+The player window is where the player controls are defined, like "Play" and "Pause". When the user interacts with the player controls, a message is sent down to the appropriate ``PictureInPictureChild`` to call the appropriate method on the underlying ``<video>`` element in the originating tab.
+
+
+Cloning the video frames
+========================
+
+While it appears as if the video is moving from the original ``<video>`` element to the player window, what's actually occurring is that the video frames are being *cloned* to the player window ``<video>`` element. This cloning is done at the platform level using a privileged method on the ``<video>`` element: ``cloneElementVisually``.
+
+
+``cloneElementVisually``
+------------------------
+
+.. code-block:: js
+
+    Promise<void> video.cloneElementVisually(otherVideo);
+
+This will clone the frames being decoded for ``video`` and display them on the ``otherVideo`` element as well. The returned Promise resolves once the cloning has successfully started.
+
+
+``stopCloningElementVisually``
+------------------------------
+
+.. code-block:: js
+
+    void video.stopCloningElementVisually();
+
+If ``video`` is being cloned visually to another element, calling this method will stop the cloning.
+
+
+``isCloningElementVisually``
+----------------------------
+
+.. code-block:: js
+
+    boolean video.isCloningElementVisually;
+
+A read-only value that returns ``true`` if ``video`` is being cloned visually.
+
+Site-specific video wrappers
+============================
+
+A site-specific video wrapper allows for the creation of custom scripts that the Picture-in-Picture component can utilize when videos are loaded in specific domains. Currently, some uses of video wrappers include:
+
+* Integration of captions and subtitles support on certain video streaming sites
+* Fixing inconsistent video behaviour when using Picture-in-Picture controls
+* Hiding the Picture-in-Picture toggle for videos on particular areas of a page, given a URL (rather than hiding the toggle for all videos on a page)
+
+``PictureInPictureChildVideoWrapper`` and ``videoWrapperScriptPath``
+--------------------------------------------------------------------
+``PictureInPictureChildVideoWrapper`` is a special class that represents a video wrapper. It is defined in ``PictureInPictureChild.sys.mjs`` and maps to a ``videoWrapperScriptPath``, which is the path of the custom wrapper script to use.
+``videoWrapperScriptPath`` is defined in `browser/extensions/pictureinpicture/data/picture_in_picture_overrides.js <https://searchfox.org/mozilla-central/source/browser/extensions/pictureinpicture/data/picture_in_picture_overrides.js>`_ for a domain,
+and custom wrapper scripts are defined in `browser/extensions/pictureinpicture/video-wrappers <https://searchfox.org/mozilla-central/source/browser/extensions/pictureinpicture/video-wrappers>`_.
+
+If a ``videoWrapperScriptPath`` is detected while initializing the Picture-in-Picture toggle or window, we immediately create a new instance of ``PictureInPictureChildVideoWrapper`` based on the given path, allowing us to run our custom scripts.
+
+API
+^^^
+See the full list of methods at `API References <#toolkit-actors-pictureinpicturechild-jsm>`_.
+
+Sandbox
+^^^^^^^
+Performing video control operations on the originating video requires executing code in the browser content. For security reasons, we utilize a *sandbox* to isolate these operations and prevent direct access to ``PictureInPictureChild``. In other words, we run content code within the sandbox itself.
+However, it is necessary to waive :ref:`xray vision <Waiving_Xray_vision>` so that we can execute the video control operations. This is done by reading the wrapper’s ``.wrappedJSObject`` property.
+
+Adding a new site-specific video wrapper
+----------------------------------------
+Creating a new wrapper script file
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+Add a new JS file for the new video wrapper in `browser/extensions/pictureinpicture/video-wrappers <https://searchfox.org/mozilla-central/source/browser/extensions/pictureinpicture/video-wrappers>`_.
+The file must meet several requirements to get the wrapper working.
+
+**Script file requirements**:
+
+* Defined class ``PictureInPictureVideoWrapper``
+* Assigned ``this.PictureInPictureVideoWrapper = PictureInPictureVideoWrapper``
+
+**PictureInPictureVideoWrapper class requirements**:
+
+* Implementation of at least one overridable method (see :ref:`picture_in_picture_child_video_wrapper_api`)
+
+**Overriden method requirements**:
+
+* Return value with a type that corresponds to ``validateRetVal`` in ``PictureInPictureChildVideoWrapper.#callWrapperMethod()``
+
+Below is an example of a script file ``mock-wrapper.js`` that overrides an existing method ``setMuted()`` in ``PictureInPictureChildVideoWrapper``:
+
+.. code-block:: js
+
+   // sample file `mock-wrapper.js`
+   class PictureInPictureVideoWrapper {
+      setMuted(video, shouldMute) {
+         if (video.muted !== shouldMute) {
+            let muteButton = document.querySelector("#player .mute-button");
+            if (muteButton) {
+               muteButton.click();
+            } else {
+               video.muted = shouldMute;
+            }
+         }
+      }
+   }
+
+   this.PictureInPictureVideoWrapper = PictureInPictureVideoWrapper
+
+.. note::
+    If a new ``PictureInPictureChildVideoWrapper`` video control method is needed, see `Adding a new video control method`_.
+
+Declaring ``videoWrapperScriptPath``
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+Declare a property ``videoWrapperScriptPath`` for the site at `browser/extensions/pictureinpicture/data/picture_in_picture_overrides.js <https://searchfox.org/mozilla-central/source/browser/extensions/pictureinpicture/data/picture_in_picture_overrides.js>`_:
+
+.. code-block:: js
+
+   someWebsite: {
+     "https://*.somewebsite.com/*": {
+       videoWrapperScriptPath: "video-wrappers/mock-wrapper.js",
+     },
+   }
+
+In this example, the URL pattern ``https://*.somewebsite.com/*`` is provided for a site named  ``someWebsite``.
+Picture-in-Picture checks for any overrides upon initialization, and it will load scripts specified by ``videoWrapperScriptPath``.
+The scripts located at ``video-wrappers/mock-wrapper.js`` will therefore run whenever we view a video from a URL matching ``somewebsite.com``.
+
+Registering the new wrapper in ``moz.build``
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+We should update `browser/extensions/pictureinpicture/moz.build <https://searchfox.org/mozilla-central/source/browser/extensions/pictureinpicture/moz.build>`_ by adding the path of the newly created wrapper:
+
+.. code-block:: js
+
+    FINAL_TARGET_FILES.features["pictureinpicture@mozilla.org"]["video-wrappers"] += [
+        "video-wrappers/mock-wrapper.js",
+        "video-wrappers/netflix.js",
+        "video-wrappers/youtube.js",
+    ]
+
+As expected for any ``moz.build`` file, order matters. Registered paths should be listed in alphabetical order. Otherwise, the build will fail.
+
+Adding a new video control method
+---------------------------------
+If none of the existing overridable methods in ``PictureInPictureChildVideoWrapper`` are applicable for a bug fix or feature enhancement,
+we can create a new one by calling ``#callWrapperMethod()``. Below is an example of how we would define a new overridable method ``setMuted()``:
+
+.. code-block:: js
+
+    // class PictureInPictureChildVideoWrapper in PictureInPictureChild.sys.mjs
+    setMuted(video, shouldMute) {
+        return this.#callWrapperMethod({
+            name: "setMuted",
+            args: [video, shouldMute],
+            fallback: () => {
+                video.muted = shouldMute;
+            },
+            validateRetVal: retVal => retVal == null,
+        });
+    }
+
+The new method passes to ``#callWrapperMethod()``:
+
+#. The method name
+#. The expected arguments that a wrapper script may use
+#. A fallback function
+#. A conditional expression that validates the return value
+
+The fallback function only executes if a wrapper script fails or if the method is not overriden.
+``validateRetVal`` checks the type of the return value and ensures it matches the expected type. If there is no return value, simply validate if type is ``null``.
+
+.. note::
+    Generic method names are preferred so that they can be used for any video wrapper.
+    For example: instead of naming a method ``updateCaptionsContainerForSiteA()``, use ``updateCaptionsContainer()``.
+
+Using the new video control method
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+Once the new method is defined, it can be used throughout ``PictureInPictureChild.sys.mjs``. In the current example, we call
+``PictureInPictureChildVideoWrapper.setMuted()`` to mute or unmute a video. ``this.videoWrapper`` is an instance of
+``PictureInPictureChildVideoWrapper``:
+
+.. code-block:: js
+
+    // class PictureInPictureChild in PictureInPictureChild.sys.mjs
+    mute() {
+        let video = this.getWeakVideo();
+        if (video && this.videoWrapper) {
+            this.videoWrapper.setMuted(video, true);
+        }
+    }
+
+    unmute() {
+        let video = this.getWeakVideo();
+        if (video && this.videoWrapper) {
+            this.videoWrapper.setMuted(video, false);
+        }
+    }
+
+Testing site-specific video wrappers
+------------------------------------
+Automated Tests
+^^^^^^^^^^^^^^^
+Automated tests for site specific wrappers are currently limited. New tests can be made in `browser/extensions/pictureinpicture/tests/browser <https://searchfox.org/mozilla-central/source/browser/extensions/pictureinpicture/tests/browser>`_ to ensure
+general functionality, but these are restricted to Firefox Nightly and do not test functionality on specific sites.
+
+Some challenges with writing tests include:
+
+* Accessing DRM content
+* Log-in credentials if a site requires a user account
+* Detecting modifications to a web page or video player that render a wrapper script obsolete
+
+Manual Tests
+^^^^^^^^^^^^
+The go-to approach right now is to test video wrappers manually, in tandem with reviews provided by the phabricator group `#pip-reviewers <https://phabricator.services.mozilla.com/project/profile/163/>`_. Below are some questions that reviewers will consider:
+
+* Does Picture-in-Picture crash or freeze?
+* Does the wrapper work on Windows, MacOS, and Linux?
+* Do Picture-in-Picture features work as expected? (Picture-in-Picture toggle, text tracks, video controls, etc.)
+* Do existing automated tests work as they should?
+
+.. warning::
+    DRM content may not load for all local Firefox builds. One possible solution is to test the video wrapper in a try build (ex. Linux).
+    Depending on the changes made, we may also require the script to run under a temporary pref such as ``media.videocontrols.picture-in-picture.WIP.someWebsiteWrapper`` for the purpose of testing changes in Firefox Nightly.
+
+API References
+==============
+``toolkit/components/pictureinpicture``
+---------------------------------------
+.. toctree::
+   :maxdepth: 1
+
+   picture-in-picture-api
+   player-api
+
+``toolkit/actors/PictureInPictureChild.sys.mjs``
+------------------------------------------------
+* :ref:`picture_in_picture_child_video_wrapper_api`
diff --git a/toolkit/components/pictureinpicture/docs/picture-in-picture-api.rst b/toolkit/components/pictureinpicture/docs/picture-in-picture-api.rst
new file mode 100644
index 0000000000..06f2ea5fc4
--- /dev/null
+++ b/toolkit/components/pictureinpicture/docs/picture-in-picture-api.rst
@@ -0,0 +1,4 @@
+PictureInPicture Reference
+===========================
+.. js:autoclass:: PictureInPicture
+  :members:
diff --git a/toolkit/components/pictureinpicture/docs/player-api.rst b/toolkit/components/pictureinpicture/docs/player-api.rst
new file mode 100644
index 0000000000..a990967dc1
--- /dev/null
+++ b/toolkit/components/pictureinpicture/docs/player-api.rst
@@ -0,0 +1,4 @@
+Player Reference
+======================
+.. js:autoclass:: Player
+  :members:
diff --git a/toolkit/components/pictureinpicture/jar.mn b/toolkit/components/pictureinpicture/jar.mn
new file mode 100644
index 0000000000..19d9717138
--- /dev/null
+++ b/toolkit/components/pictureinpicture/jar.mn
@@ -0,0 +1,8 @@
+#filter substitution
+# 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/.
+
+toolkit.jar:
+* content/global/pictureinpicture/player.xhtml   (content/player.xhtml)
+  content/global/pictureinpicture/player.js      (content/player.js)
diff --git a/toolkit/components/pictureinpicture/moz.build b/toolkit/components/pictureinpicture/moz.build
new file mode 100644
index 0000000000..8c697f81ae
--- /dev/null
+++ b/toolkit/components/pictureinpicture/moz.build
@@ -0,0 +1,21 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# 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/.
+
+with Files("**"):
+    BUG_COMPONENT = ("Toolkit", "Picture-in-Picture")
+
+SPHINX_TREES["pictureinpicture"] = "docs"
+
+JAR_MANIFESTS += ["jar.mn"]
+
+EXTRA_JS_MODULES += [
+    "PictureInPicture.sys.mjs",
+    "PictureInPictureControls.sys.mjs",
+]
+
+BROWSER_CHROME_MANIFESTS += [
+    "tests/browser.ini",
+]
diff --git a/toolkit/components/pictureinpicture/tests/browser.ini b/toolkit/components/pictureinpicture/tests/browser.ini
new file mode 100644
index 0000000000..9eccc6df9a
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser.ini
@@ -0,0 +1,155 @@
+[DEFAULT]
+support-files =
+  click-event-helper.js
+  head.js
+  short.mp4
+  no-audio-track.webm
+  test-button-overlay.html
+  test-media-stream.html
+  test-opaque-overlay.html
+  test-page.html
+  test-page-without-audio.html
+  test-page-multiple-contexts.html
+  test-page-pipDisabled.html
+  test-page-with-iframe.html
+  test-page-with-sound.html
+  test-page-with-webvtt.html
+  test-pointer-events-none.html
+  test-reversed.html
+  test-transparent-nested-iframes.html
+  test-transparent-overlay-1.html
+  test-transparent-overlay-2.html
+  test-video.mp4
+  test-video-cropped.mp4
+  test-video-long.mp4
+  test-video-selection.html
+  test-video-vertical.mp4
+  test-webvtt-1.vtt
+  test-webvtt-2.vtt
+  test-webvtt-3.vtt
+  test-webvtt-4.vtt
+  test-webvtt-5.vtt
+  ../../../../dom/media/test/gizmo.mp4
+  ../../../../dom/media/test/owl.mp3
+
+prefs =
+  media.videocontrols.picture-in-picture.display-text-tracks.enabled=false
+  media.videocontrols.picture-in-picture.enabled=true
+  media.videocontrols.picture-in-picture.video-toggle.always-show=true
+  media.videocontrols.picture-in-picture.video-toggle.enabled=true
+  media.videocontrols.picture-in-picture.video-toggle.has-used=true
+  media.videocontrols.picture-in-picture.video-toggle.position="right"
+  media.videocontrols.picture-in-picture.video-toggle.testing=true
+  media.videocontrols.picture-in-picture.urlbar-button.enabled=true
+
+[browser_aaa_run_first_firstTimePiPToggleEvents.js]
+[browser_aaa_telemetry_togglePiP.js]
+[browser_backgroundTab.js]
+[browser_cannotTriggerFromContent.js]
+[browser_changePiPSrcInFullscreen.js]
+[browser_closePipPause.js]
+[browser_closePip_pageNavigationChanges.js]
+[browser_closePlayer.js]
+[browser_closeTab.js]
+[browser_close_unpip_focus.js]
+[browser_conflictingPips.js]
+[browser_contextMenu.js]
+skip-if = os == "linux" && bits == 64 && os_version == "18.04" # Bug 1569205
+[browser_controlsHover.js]
+[browser_cornerSnapping.js]
+run-if = os == "mac"
+[browser_dblclickFullscreen.js]
+[browser_durationChange.js]
+[browser_flipIconWithRTL.js]
+skip-if =
+  os == "linux" && ccov # Bug 1678091
+  tsan # Bug 1678091
+[browser_fontSize_change.js]
+[browser_fullscreen.js]
+skip-if = (os == "mac" && debug) || os == "linux" #Bug 1566173, Bug 1664667
+[browser_improved_controls.js]
+[browser_keyboardClosePIPwithESC.js]
+[browser_keyboardFullScreenPIPShortcut.js]
+[browser_keyboardShortcut.js]
+[browser_keyboardShortcutClosePIP.js]
+[browser_keyboardShortcutWithNanDuration.js]
+support-files =
+  test-page-with-nan-video-duration.html
+[browser_keyboardToggle.js]
+[browser_mediaStreamVideos.js]  
+[browser_mouseButtonVariation.js]
+skip-if =
+  debug
+  os == 'linux' && bits == 64 && !debug # Bug 1549875
+[browser_multiPip.js]
+[browser_nimbusDisplayDuration.js]
+[browser_nimbusFirstTimeStyleVariant.js]
+[browser_nimbusMessageFirstTimePip.js]
+[browser_nimbusShowIconOnly.js]
+[browser_noPlayerControlsOnMiddleRightClick.js]
+[browser_noToggleOnAudio.js]
+[browser_occluded_window.js]
+[browser_playerControls.js]
+[browser_preserveTabPipIconOverlay.js]
+[browser_privateWindow.js]
+[browser_removeVideoElement.js]
+[browser_resizeVideo.js]
+skip-if = os == 'linux' # Bug 1594223
+[browser_reversePiP.js]
+[browser_saveLastPiPLoc.js]
+skip-if =
+  os == "linux" # Bug 1673465
+  os == "win" && bits == 64 && debug # Bug 1683002
+[browser_shortcutsAfterFocus.js]
+skip-if = os == "win" && bits == 64 && debug # Bug 1683002
+[browser_showMessage.js]
+[browser_smallVideoLayout.js]
+skip-if = os == "win" && bits == 64 && debug # Bug 1683002
+[browser_stripVideoStyles.js]
+[browser_subtitles_settings_panel.js]
+[browser_tabIconOverlayPiP.js]
+[browser_telemetry_enhancements.js]
+[browser_text_tracks_webvtt_1.js]
+[browser_text_tracks_webvtt_2.js]
+[browser_text_tracks_webvtt_3.js]
+[browser_thirdPartyIframe.js]
+[browser_toggleAfterTabTearOutIn.js]
+skip-if = (os == 'linux' && bits == 64) || (os == 'mac' && !asan && !debug) # Bug 1605546
+[browser_toggleButtonOnNanDuration.js]
+skip-if =
+  os == 'linux' && !debug # Bug 1700504
+support-files =
+  test-page-with-nan-video-duration.html
+[browser_toggleButtonOverlay.js]
+skip-if = true # Bug 1546455
+[browser_toggleMode_2.js]
+skip-if =
+  os == 'linux' # Bug 1654971
+  os == 'mac'  # Bug 1654971
+[browser_toggleOnInsertedVideo.js]
+[browser_toggleOpaqueOverlay.js]
+skip-if = true # Bug 1546455
+[browser_togglePointerEventsNone.js]
+skip-if = true # Bug 1664920, Bug 1628777
+[browser_togglePolicies.js]
+skip-if =
+  os == "linux" && bits == 64 # Bug 1605565
+  os == "mac" && os_version == "10.15" && debug # Bug 1605565
+[browser_togglePositionChange.js]
+skip-if = 
+  os == "linux" && bits == 64 && !debug # Bug 1738532
+[browser_toggleSimple.js]
+skip-if = os == 'linux' # Bug 1546455
+[browser_toggleTransparentOverlay-1.js]
+skip-if =
+  os == 'linux' && bits == 64 # Bug 1552288
+[browser_toggleTransparentOverlay-2.js]
+skip-if =
+  os == 'linux' && bits == 64 && os_version == '18.04' # Bug 1546930
+[browser_toggle_enabled.js]
+[browser_toggle_without_audio.js]
+[browser_toggle_videocontrols.js]
+[browser_touch_toggle_enablepip.js]
+[browser_urlbar_toggle.js]
+[browser_videoEmptied.js]
+[browser_videoSelection.js]
diff --git a/toolkit/components/pictureinpicture/tests/browser_aaa_run_first_firstTimePiPToggleEvents.js b/toolkit/components/pictureinpicture/tests/browser_aaa_run_first_firstTimePiPToggleEvents.js
new file mode 100644
index 0000000000..f25bc602a3
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_aaa_run_first_firstTimePiPToggleEvents.js
@@ -0,0 +1,314 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { TelemetryTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/TelemetryTestUtils.sys.mjs"
+);
+
+const FIRST_TIME_PIP_TOGGLE_STYLES = {
+  rootID: "pictureInPictureToggle",
+  stages: {
+    hoverVideo: {
+      opacities: {
+        ".pip-wrapper": DEFAULT_TOGGLE_OPACITY,
+      },
+      hidden: [],
+    },
+
+    hoverToggle: {
+      opacities: {
+        ".pip-wrapper": 1.0,
+      },
+      hidden: [],
+    },
+  },
+};
+
+const FIRST_CONTEXT_MENU_EXPECTED_EVENTS = [
+  [
+    "pictureinpicture",
+    "opened_method",
+    "contextMenu",
+    null,
+    { firstTimeToggle: "true" },
+  ],
+];
+
+const SECOND_CONTEXT_MENU_EXPECTED_EVENTS = [
+  [
+    "pictureinpicture",
+    "opened_method",
+    "contextMenu",
+    null,
+    { firstTimeToggle: "false" },
+  ],
+];
+
+const FIRST_TOGGLE_EXPECTED_EVENTS = [
+  ["pictureinpicture", "saw_toggle", "toggle", null, { firstTime: "true" }],
+  [
+    "pictureinpicture",
+    "opened_method",
+    "toggle",
+    null,
+    { firstTimeToggle: "true" },
+  ],
+];
+
+const SECOND_TOGGLE_EXPECTED_EVENTS = [
+  ["pictureinpicture", "saw_toggle", "toggle", null, { firstTime: "false" }],
+  [
+    "pictureinpicture",
+    "opened_method",
+    "toggle",
+    null,
+    { firstTimeToggle: "false" },
+  ],
+];
+
+/**
+ * This function will open the PiP window by clicking the toggle
+ * and then close the PiP window
+ * @param browser The current browser
+ * @param videoID The video element id
+ */
+async function openAndClosePipWithToggle(browser, videoID) {
+  await SimpleTest.promiseFocus(browser);
+  await ensureVideosReady(browser);
+
+  await prepareForToggleClick(browser, videoID);
+
+  await clearAllContentEvents();
+
+  // Hover the mouse over the video to reveal the toggle, which is necessary
+  // if we want to click on the toggle.
+  await BrowserTestUtils.synthesizeMouseAtCenter(
+    `#${videoID}`,
+    {
+      type: "mousemove",
+    },
+    browser
+  );
+  await BrowserTestUtils.synthesizeMouseAtCenter(
+    `#${videoID}`,
+    {
+      type: "mouseover",
+    },
+    browser
+  );
+
+  info("Waiting for toggle to become visible");
+  await toggleOpacityReachesThreshold(
+    browser,
+    videoID,
+    "hoverVideo",
+    FIRST_TIME_PIP_TOGGLE_STYLES
+  );
+
+  let toggleClientRect = await getToggleClientRect(browser, videoID);
+
+  // The toggle center, because of how it slides out, is actually outside
+  // of the bounds of a click event. For now, we move the mouse in by a
+  // hard-coded 15 pixels along the x and y axis to achieve the hover.
+  let toggleLeft = toggleClientRect.left + 15;
+  let toggleTop = toggleClientRect.top + 15;
+
+  info("Clicking on toggle, and expecting a Picture-in-Picture window to open");
+  // We need to wait for the window to have completed loading before we
+  // can close it as the document's type required by closeWindow may not
+  // be available.
+  let domWindowOpened = BrowserTestUtils.domWindowOpenedAndLoaded(null);
+
+  await BrowserTestUtils.synthesizeMouseAtPoint(
+    toggleLeft,
+    toggleTop,
+    {
+      type: "mousedown",
+    },
+    browser
+  );
+
+  await BrowserTestUtils.synthesizeMouseAtPoint(
+    1,
+    1,
+    {
+      type: "mouseup",
+    },
+    browser
+  );
+
+  let win = await domWindowOpened;
+  ok(win, "A Picture-in-Picture window opened.");
+
+  await SpecialPowers.spawn(browser, [videoID], async videoID => {
+    let video = content.document.getElementById(videoID);
+    await ContentTaskUtils.waitForCondition(() => {
+      return video.isCloningElementVisually;
+    }, "Video is being cloned visually.");
+  });
+
+  await BrowserTestUtils.closeWindow(win);
+  await assertSawMouseEvents(browser, false);
+
+  await BrowserTestUtils.synthesizeMouseAtPoint(1, 1, {}, browser);
+  await assertSawMouseEvents(browser, true);
+}
+
+/**
+ * This function will open the PiP window by with the context menu
+ * @param browser The current browser
+ * @param videoID The video element id
+ */
+async function openAndClosePipWithContextMenu(browser, videoID) {
+  await SimpleTest.promiseFocus(browser);
+  await ensureVideosReady(browser);
+
+  let menu = document.getElementById("contentAreaContextMenu");
+  let popupshown = BrowserTestUtils.waitForPopupEvent(menu, "shown");
+
+  await BrowserTestUtils.synthesizeMouseAtCenter(
+    `#${videoID}`,
+    {
+      type: "contextmenu",
+    },
+    browser
+  );
+
+  await popupshown;
+  let isContextMenuOpen = menu.state === "showing" || menu.state === "open";
+  ok(isContextMenuOpen, "Context menu is open");
+
+  let domWindowOpened = BrowserTestUtils.domWindowOpenedAndLoaded(null);
+
+  // clear content events
+  await clearAllContentEvents();
+
+  let hidden = BrowserTestUtils.waitForPopupEvent(menu, "hidden");
+  menu.activateItem(menu.querySelector("#context-video-pictureinpicture"));
+  await hidden;
+
+  let win = await domWindowOpened;
+  ok(win, "A Picture-in-Picture window opened.");
+
+  await SpecialPowers.spawn(browser, [videoID], async videoID => {
+    let video = content.document.getElementById(videoID);
+    await ContentTaskUtils.waitForCondition(() => {
+      return video.isCloningElementVisually;
+    }, "Video is being cloned visually.");
+  });
+
+  await BrowserTestUtils.closeWindow(win);
+}
+
+async function clearAllContentEvents() {
+  // Clear everything.
+  await TestUtils.waitForCondition(() => {
+    Services.telemetry.clearEvents();
+    let events = Services.telemetry.snapshotEvents(
+      Ci.nsITelemetry.DATASET_PRERELEASE_CHANNELS,
+      true
+    ).content;
+    return !events || !events.length;
+  });
+}
+
+add_task(async function test_eventTelemetry() {
+  Services.telemetry.clearEvents();
+  await clearAllContentEvents();
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: TEST_PAGE,
+    },
+    async browser => {
+      Services.telemetry.setEventRecordingEnabled("pictureinpicture", true);
+      let videoID = "no-controls";
+
+      const PIP_PREF =
+        "media.videocontrols.picture-in-picture.video-toggle.has-used";
+      await SpecialPowers.pushPrefEnv({
+        set: [[PIP_PREF, false]],
+      });
+
+      // open with context menu for first time
+      await openAndClosePipWithContextMenu(browser, videoID);
+
+      let filter = {
+        category: "pictureinpicture",
+        method: "opened_method",
+        object: "contextMenu",
+      };
+      await waitForTelemeryEvents(
+        filter,
+        FIRST_CONTEXT_MENU_EXPECTED_EVENTS.length,
+        "content"
+      );
+
+      TelemetryTestUtils.assertEvents(
+        FIRST_CONTEXT_MENU_EXPECTED_EVENTS,
+        filter,
+        { clear: true, process: "content" }
+      );
+
+      // open with toggle for first time
+      await SpecialPowers.pushPrefEnv({
+        set: [[PIP_PREF, false]],
+      });
+
+      await openAndClosePipWithToggle(browser, videoID);
+
+      filter = {
+        category: "pictureinpicture",
+      };
+      await waitForTelemeryEvents(
+        filter,
+        FIRST_TOGGLE_EXPECTED_EVENTS.length,
+        "content"
+      );
+
+      TelemetryTestUtils.assertEvents(FIRST_TOGGLE_EXPECTED_EVENTS, filter, {
+        clear: true,
+        process: "content",
+      });
+
+      // open with toggle for not first time
+      await openAndClosePipWithToggle(browser, videoID);
+
+      filter = {
+        category: "pictureinpicture",
+      };
+      await waitForTelemeryEvents(
+        filter,
+        SECOND_TOGGLE_EXPECTED_EVENTS.length,
+        "content"
+      );
+
+      TelemetryTestUtils.assertEvents(SECOND_TOGGLE_EXPECTED_EVENTS, filter, {
+        clear: true,
+        process: "content",
+      });
+
+      // open with context menu for not first time
+      await openAndClosePipWithContextMenu(browser, videoID);
+
+      filter = {
+        category: "pictureinpicture",
+        method: "opened_method",
+        object: "contextMenu",
+      };
+      await waitForTelemeryEvents(
+        filter,
+        SECOND_CONTEXT_MENU_EXPECTED_EVENTS.length,
+        "content"
+      );
+
+      TelemetryTestUtils.assertEvents(
+        SECOND_CONTEXT_MENU_EXPECTED_EVENTS,
+        filter,
+        { true: false, process: "content" }
+      );
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_aaa_telemetry_togglePiP.js b/toolkit/components/pictureinpicture/tests/browser_aaa_telemetry_togglePiP.js
new file mode 100644
index 0000000000..d6a7540e15
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_aaa_telemetry_togglePiP.js
@@ -0,0 +1,69 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+function getTelemetryToggleEnabled() {
+  const scalarData = Services.telemetry.getSnapshotForScalars(
+    "main",
+    false
+  ).parent;
+  return scalarData["pictureinpicture.toggle_enabled"];
+}
+
+/**
+ * Tests telemetry for user toggling on or off PiP.
+ */
+add_task(async () => {
+  const TOGGLE_PIP_ENABLED_PREF =
+    "media.videocontrols.picture-in-picture.video-toggle.enabled";
+
+  await SpecialPowers.pushPrefEnv({
+    set: [[TOGGLE_PIP_ENABLED_PREF, true]],
+  });
+
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE,
+      gBrowser,
+    },
+    async browser => {
+      await ensureVideosReady(browser);
+
+      let contextPiPDisable = document.getElementById(
+        "context_HidePictureInPictureToggle"
+      );
+      contextPiPDisable.click();
+      const enabled = Services.prefs.getBoolPref(
+        TOGGLE_PIP_ENABLED_PREF,
+        false
+      );
+
+      Assert.equal(enabled, false, "PiP is disabled.");
+
+      await TestUtils.waitForCondition(() => {
+        return getTelemetryToggleEnabled() === false;
+      });
+
+      Assert.equal(
+        getTelemetryToggleEnabled(),
+        false,
+        "PiP is disabled according to Telemetry."
+      );
+
+      await SpecialPowers.pushPrefEnv({
+        set: [[TOGGLE_PIP_ENABLED_PREF, true]],
+      });
+
+      await TestUtils.waitForCondition(() => {
+        return getTelemetryToggleEnabled() === true;
+      });
+
+      Assert.equal(
+        getTelemetryToggleEnabled(),
+        true,
+        "PiP is enabled according to Telemetry."
+      );
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_backgroundTab.js b/toolkit/components/pictureinpicture/tests/browser_backgroundTab.js
new file mode 100644
index 0000000000..e1f96748a5
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_backgroundTab.js
@@ -0,0 +1,93 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+/**
+ * This test creates a PiP window, then switches to another tab and confirms
+ * that the PiP tab is still active.
+ */
+add_task(async () => {
+  let videoID = "no-controls";
+  let firstTab = gBrowser.selectedTab;
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE,
+      gBrowser,
+    },
+    async browser => {
+      let originatingTab = gBrowser.getTabForBrowser(browser);
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      await BrowserTestUtils.switchTab(gBrowser, firstTab);
+
+      let switcher = gBrowser._getSwitcher();
+
+      Assert.equal(
+        switcher.getTabState(originatingTab),
+        switcher.STATE_LOADED,
+        "The originating browser tab should be in STATE_LOADED."
+      );
+      Assert.equal(
+        browser.docShellIsActive,
+        true,
+        "The docshell should be active in the originating tab"
+      );
+
+      // We need to destroy the current AsyncTabSwitcher to avoid
+      // tabrowser.shouldActivateDocShell going in the
+      // AsyncTabSwitcher.shouldActivateDocShell code path which isn't PiP aware.
+      switcher.destroy();
+
+      // Closing with window.close doesn't actually pause the video, so click
+      // the close button instead.
+      pipWin.document.getElementById("close").click();
+      await BrowserTestUtils.windowClosed(pipWin);
+
+      Assert.equal(
+        browser.docShellIsActive,
+        false,
+        "The docshell should be inactive in the originating tab"
+      );
+    }
+  );
+});
+
+/**
+ * This test creates a PiP window, then minimizes the browser and confirms
+ * that the PiP tab is still active.
+ */
+add_task(async () => {
+  let videoID = "no-controls";
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE,
+      gBrowser,
+    },
+    async browser => {
+      let originatingTab = gBrowser.getTabForBrowser(browser);
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      let promiseSizeModeChange = BrowserTestUtils.waitForEvent(
+        window,
+        "sizemodechange"
+      );
+      window.minimize();
+      await promiseSizeModeChange;
+
+      let switcher = gBrowser._getSwitcher();
+
+      Assert.equal(
+        switcher.getTabState(originatingTab),
+        switcher.STATE_LOADED,
+        "The originating browser tab should be in STATE_LOADED."
+      );
+
+      await BrowserTestUtils.closeWindow(pipWin);
+
+      // Workaround bug 1782134.
+      window.restore();
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_cannotTriggerFromContent.js b/toolkit/components/pictureinpicture/tests/browser_cannotTriggerFromContent.js
new file mode 100644
index 0000000000..4c3d32b474
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_cannotTriggerFromContent.js
@@ -0,0 +1,32 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests that the MozTogglePictureInPicture event is ignored if
+ * fired by unprivileged web content.
+ */
+add_task(async () => {
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE,
+      gBrowser,
+    },
+    async browser => {
+      // For now, the easiest way to ensure that this didn't happen is to fail
+      // if we receive the PictureInPicture:Request message.
+      const MESSAGE = "PictureInPicture:Request";
+      let sawMessage = false;
+      let listener = msg => {
+        sawMessage = true;
+      };
+      browser.messageManager.addMessageListener(MESSAGE, listener);
+      await SpecialPowers.spawn(browser, [], async () => {
+        content.wrappedJSObject.fireEvents();
+      });
+      browser.messageManager.removeMessageListener(MESSAGE, listener);
+      ok(!sawMessage, "Got PictureInPicture:Request message unexpectedly.");
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_changePiPSrcInFullscreen.js b/toolkit/components/pictureinpicture/tests/browser_changePiPSrcInFullscreen.js
new file mode 100644
index 0000000000..e971f17296
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_changePiPSrcInFullscreen.js
@@ -0,0 +1,511 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { sinon } = ChromeUtils.importESModule(
+  "resource://testing-common/Sinon.sys.mjs"
+);
+
+const NEW_VIDEO_ASPECT_RATIO = 1.334;
+
+async function switchVideoSource(browser, src) {
+  await ContentTask.spawn(browser, { src }, async ({ src }) => {
+    let doc = content.document;
+    let video = doc.getElementById("no-controls");
+    video.src = src;
+  });
+}
+
+/**
+ *
+ * @param {Object} actual The actual size and position of the window
+ * @param {Object} expected The expected size and position of the window
+ * @param {String} message A message to print before asserting the size and position
+ */
+function assertEvent(actual, expected, message) {
+  info(message);
+  isfuzzy(
+    actual.width,
+    expected.width,
+    ACCEPTABLE_DIFFERENCE,
+    `The actual width: ${actual.width}. The expected width: ${expected.width}`
+  );
+  isfuzzy(
+    actual.height,
+    expected.height,
+    ACCEPTABLE_DIFFERENCE,
+    `The actual height: ${actual.height}. The expected height: ${expected.height}`
+  );
+  isfuzzy(
+    actual.left,
+    expected.left,
+    ACCEPTABLE_DIFFERENCE,
+    `The actual left: ${actual.left}. The expected left: ${expected.left}`
+  );
+  isfuzzy(
+    actual.top,
+    expected.top,
+    ACCEPTABLE_DIFFERENCE,
+    `The actual top: ${actual.top}. The expected top: ${expected.top}`
+  );
+}
+
+/**
+ * This test is our control test. This tests that when the PiP window exits
+ * fullscreen it will return to the size it was before being fullscreened.
+ */
+add_task(async function testNoSrcChangeFullscreen() {
+  // After opening the PiP window, it is resized to 640x360. There is a change
+  // the PiP window will open with that size. To prevent that we override the
+  // last saved position so we open at (0, 0) and 300x300.
+  overrideSavedPosition(0, 0, 300, 300);
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE,
+      gBrowser,
+    },
+    async browser => {
+      await ensureVideosReady(browser);
+      let pipWin = await triggerPictureInPicture(browser, "no-controls");
+      let controls = pipWin.document.getElementById("controls");
+      const screen = pipWin.screen;
+
+      let resizeEventArray = [];
+      pipWin.addEventListener("resize", event => {
+        let win = event.target;
+        let obj = {
+          width: win.innerWidth,
+          height: win.innerHeight,
+          left: win.screenLeft,
+          top: win.screenTop,
+        };
+        resizeEventArray.push(obj);
+      });
+
+      // Move the PiP window to an unsaved location
+      let left = 100;
+      let top = 100;
+      pipWin.moveTo(left, top);
+
+      await BrowserTestUtils.waitForCondition(
+        () => pipWin.screenLeft === 100 && pipWin.screenTop === 100,
+        "Waiting for PiP to move to 100, 100"
+      );
+
+      let width = 640;
+      let height = 360;
+
+      let resizePromise = BrowserTestUtils.waitForEvent(pipWin, "resize");
+      pipWin.resizeTo(width, height);
+      await resizePromise;
+
+      Assert.equal(
+        resizeEventArray.length,
+        1,
+        "resizeEventArray should have 1 event"
+      );
+
+      let actualEvent = resizeEventArray.splice(0, 1)[0];
+      let expectedEvent = { width, height, left, top };
+      assertEvent(
+        actualEvent,
+        expectedEvent,
+        "The PiP window has been correctly positioned before fullscreen"
+      );
+
+      await promiseFullscreenEntered(pipWin, async () => {
+        EventUtils.sendMouseEvent(
+          {
+            type: "dblclick",
+          },
+          controls,
+          pipWin
+        );
+      });
+
+      Assert.equal(
+        pipWin.document.fullscreenElement,
+        pipWin.document.body,
+        "Double-click caused us to enter fullscreen."
+      );
+
+      await BrowserTestUtils.waitForCondition(
+        () => resizeEventArray.length === 1,
+        "Waiting for resizeEventArray to have 1 event"
+      );
+
+      actualEvent = resizeEventArray.splice(0, 1)[0];
+      expectedEvent = {
+        width: screen.width,
+        height: screen.height,
+        left: screen.left,
+        top: screen.top,
+      };
+      assertEvent(
+        actualEvent,
+        expectedEvent,
+        "The PiP window has been correctly fullscreened before switching source"
+      );
+
+      await promiseFullscreenExited(pipWin, async () => {
+        EventUtils.sendMouseEvent(
+          {
+            type: "dblclick",
+          },
+          controls,
+          pipWin
+        );
+      });
+
+      Assert.ok(
+        !pipWin.document.fullscreenElement,
+        "Double-click caused us to exit fullscreen."
+      );
+
+      await BrowserTestUtils.waitForCondition(
+        () => resizeEventArray.length >= 1,
+        "Waiting for resizeEventArray to have 1 event, got " +
+          resizeEventArray.length
+      );
+
+      actualEvent = resizeEventArray.splice(0, 1)[0];
+      expectedEvent = { width, height, left, top };
+      assertEvent(
+        actualEvent,
+        expectedEvent,
+        "The PiP window has been correctly positioned after exiting fullscreen"
+      );
+
+      await ensureMessageAndClosePiP(browser, "no-controls", pipWin, false);
+
+      clearSavedPosition();
+    }
+  );
+});
+
+/**
+ * This function tests changing the src of a Picture-in-Picture player while
+ * the player is fullscreened and then ensuring the that video stays
+ * fullscreened after the src change and that the player will resize to the new
+ * video size.
+ */
+add_task(async function testChangingSameSizeVideoSrcFullscreen() {
+  // After opening the PiP window, it is resized to 640x360. There is a change
+  // the PiP window will open with that size. To prevent that we override the
+  // last saved position so we open at (0, 0) and 300x300.
+  overrideSavedPosition(0, 0, 300, 300);
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE,
+      gBrowser,
+    },
+    async browser => {
+      await ensureVideosReady(browser);
+      let pipWin = await triggerPictureInPicture(browser, "no-controls");
+      let controls = pipWin.document.getElementById("controls");
+      const screen = pipWin.screen;
+      let sandbox = sinon.createSandbox();
+      let resizeToVideoSpy = sandbox.spy(pipWin, "resizeToVideo");
+
+      let resizeEventArray = [];
+      pipWin.addEventListener("resize", event => {
+        let win = event.target;
+        let obj = {
+          width: win.innerWidth,
+          height: win.innerHeight,
+          left: win.screenLeft,
+          top: win.screenTop,
+        };
+        resizeEventArray.push(obj);
+      });
+
+      // Move the PiP window to an unsaved location
+      let left = 100;
+      let top = 100;
+      pipWin.moveTo(left, top);
+
+      await BrowserTestUtils.waitForCondition(
+        () => pipWin.screenLeft === 100 && pipWin.screenTop === 100,
+        "Waiting for PiP to move to 100, 100"
+      );
+
+      let width = 640;
+      let height = 360;
+
+      let resizePromise = BrowserTestUtils.waitForEvent(pipWin, "resize");
+      pipWin.resizeTo(width, height);
+      await resizePromise;
+
+      Assert.equal(
+        resizeEventArray.length,
+        1,
+        "resizeEventArray should have 1 event"
+      );
+
+      let actualEvent = resizeEventArray.splice(0, 1)[0];
+      let expectedEvent = { width, height, left, top };
+      assertEvent(
+        actualEvent,
+        expectedEvent,
+        "The PiP window has been correctly positioned before fullscreen"
+      );
+
+      await promiseFullscreenEntered(pipWin, async () => {
+        EventUtils.sendMouseEvent(
+          {
+            type: "dblclick",
+          },
+          controls,
+          pipWin
+        );
+      });
+
+      Assert.equal(
+        pipWin.document.fullscreenElement,
+        pipWin.document.body,
+        "Double-click caused us to enter fullscreen."
+      );
+
+      await BrowserTestUtils.waitForCondition(
+        () => resizeEventArray.length === 1,
+        "Waiting for resizeEventArray to have 1 event"
+      );
+
+      actualEvent = resizeEventArray.splice(0, 1)[0];
+      expectedEvent = {
+        width: screen.width,
+        height: screen.height,
+        left: screen.left,
+        top: screen.top,
+      };
+      assertEvent(
+        actualEvent,
+        expectedEvent,
+        "The PiP window has been correctly fullscreened before switching source"
+      );
+
+      await switchVideoSource(browser, "test-video.mp4");
+
+      await BrowserTestUtils.waitForCondition(
+        () => resizeToVideoSpy.calledOnce,
+        "Waiting for deferredResize to be updated"
+      );
+
+      await promiseFullscreenExited(pipWin, async () => {
+        EventUtils.sendMouseEvent(
+          {
+            type: "dblclick",
+          },
+          controls,
+          pipWin
+        );
+      });
+
+      Assert.ok(
+        !pipWin.document.fullscreenElement,
+        "Double-click caused us to exit fullscreen."
+      );
+
+      await BrowserTestUtils.waitForCondition(
+        () => resizeEventArray.length >= 1,
+        "Waiting for resizeEventArray to have 1 event, got " +
+          resizeEventArray.length
+      );
+
+      actualEvent = resizeEventArray.splice(0, 1)[0];
+      expectedEvent = { width, height, left, top };
+      assertEvent(
+        actualEvent,
+        expectedEvent,
+        "The PiP window has been correctly positioned after exiting fullscreen"
+      );
+
+      sandbox.restore();
+      await ensureMessageAndClosePiP(browser, "no-controls", pipWin, false);
+
+      clearSavedPosition();
+    }
+  );
+});
+
+/**
+ * This is similar to the previous test but in this test we switch to a video
+ * with a different aspect ratio to confirm that the PiP window will take the
+ * new aspect ratio after exiting fullscreen. We also exit fullscreen with the
+ * escape key instead of double clicking in this test.
+ */
+add_task(async function testChangingDifferentSizeVideoSrcFullscreen() {
+  // After opening the PiP window, it is resized to 640x360. There is a change
+  // the PiP window will open with that size. To prevent that we override the
+  // last saved position so we open at (0, 0) and 300x300.
+  overrideSavedPosition(0, 0, 300, 300);
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE,
+      gBrowser,
+    },
+    async browser => {
+      await ensureVideosReady(browser);
+      let pipWin = await triggerPictureInPicture(browser, "no-controls");
+      let controls = pipWin.document.getElementById("controls");
+      const screen = pipWin.screen;
+      let sandbox = sinon.createSandbox();
+      let resizeToVideoSpy = sandbox.spy(pipWin, "resizeToVideo");
+
+      let resizeEventArray = [];
+      pipWin.addEventListener("resize", event => {
+        let win = event.target;
+        let obj = {
+          width: win.innerWidth,
+          height: win.innerHeight,
+          left: win.screenLeft,
+          top: win.screenTop,
+        };
+        resizeEventArray.push(obj);
+      });
+
+      // Move the PiP window to an unsaved location
+      let left = 100;
+      let top = 100;
+      pipWin.moveTo(left, top);
+
+      await BrowserTestUtils.waitForCondition(
+        () => pipWin.screenLeft === 100 && pipWin.screenTop === 100,
+        "Waiting for PiP to move to 100, 100"
+      );
+
+      let width = 640;
+      let height = 360;
+
+      let resizePromise = BrowserTestUtils.waitForEvent(pipWin, "resize");
+      pipWin.resizeTo(width, height);
+      await resizePromise;
+
+      Assert.equal(
+        resizeEventArray.length,
+        1,
+        "resizeEventArray should have 1 event"
+      );
+
+      let actualEvent = resizeEventArray.splice(0, 1)[0];
+      let expectedEvent = { width, height, left, top };
+      assertEvent(
+        actualEvent,
+        expectedEvent,
+        "The PiP window has been correctly positioned before fullscreen"
+      );
+
+      await promiseFullscreenEntered(pipWin, async () => {
+        EventUtils.sendMouseEvent(
+          {
+            type: "dblclick",
+          },
+          controls,
+          pipWin
+        );
+      });
+
+      Assert.equal(
+        pipWin.document.fullscreenElement,
+        pipWin.document.body,
+        "Double-click caused us to enter fullscreen."
+      );
+
+      await BrowserTestUtils.waitForCondition(
+        () => resizeEventArray.length === 1,
+        "Waiting for resizeEventArray to have 1 event"
+      );
+
+      actualEvent = resizeEventArray.splice(0, 1)[0];
+      expectedEvent = {
+        width: screen.width,
+        height: screen.height,
+        left: screen.left,
+        top: screen.top,
+      };
+      assertEvent(
+        actualEvent,
+        expectedEvent,
+        "The PiP window has been correctly fullscreened before switching source"
+      );
+
+      let previousWidth = pipWin.getDeferredResize().width;
+
+      await switchVideoSource(browser, "test-video-long.mp4");
+
+      // Confirm that we are updating the `deferredResize` and not actually resizing
+      await BrowserTestUtils.waitForCondition(
+        () => resizeToVideoSpy.calledOnce,
+        "Waiting for deferredResize to be updated"
+      );
+
+      // Confirm that we updated the deferredResize to the new width
+      await BrowserTestUtils.waitForCondition(
+        () => previousWidth !== pipWin.getDeferredResize().width,
+        "Waiting for deferredResize to update"
+      );
+
+      await promiseFullscreenExited(pipWin, async () => {
+        EventUtils.synthesizeKey("KEY_Escape", {}, pipWin);
+      });
+
+      Assert.ok(
+        !pipWin.document.fullscreenElement,
+        "Escape key caused us to exit fullscreen."
+      );
+
+      await BrowserTestUtils.waitForCondition(
+        () => resizeEventArray.length >= 1,
+        "Waiting for resizeEventArray to have 1 event, got " +
+          resizeEventArray.length
+      );
+
+      actualEvent = resizeEventArray.splice(0, 1)[0];
+      expectedEvent = {
+        width: height * NEW_VIDEO_ASPECT_RATIO,
+        height,
+        left,
+        top,
+      };
+
+      // When two resize events happen very close together we optimize by
+      // "coalescing" the two resizes into a single resize event. Sometimes
+      // the events aren't "coalesced" together (I don't know why) so I check
+      // if the most recent event is what we are looking for and if it is not
+      // then I'll wait for the resize event we are looking for.
+      if (
+        Math.abs(
+          actualEvent.width - expectedEvent.width <= ACCEPTABLE_DIFFERENCE
+        )
+      ) {
+        // The exit fullscreen resize events were "coalesced".
+        assertEvent(
+          actualEvent,
+          expectedEvent,
+          "The PiP window has been correctly positioned after exiting fullscreen"
+        );
+      } else {
+        // For some reason the exit fullscreen resize events weren't "coalesced"
+        // so we have to wait for the next resize event.
+        await BrowserTestUtils.waitForCondition(
+          () => resizeEventArray.length === 1,
+          "Waiting for resizeEventArray to have 1 event"
+        );
+
+        actualEvent = resizeEventArray.splice(0, 1)[0];
+
+        assertEvent(
+          actualEvent,
+          expectedEvent,
+          "The PiP window has been correctly positioned after exiting fullscreen"
+        );
+      }
+
+      sandbox.restore();
+      await ensureMessageAndClosePiP(browser, "no-controls", pipWin, false);
+
+      clearSavedPosition();
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_closePipPause.js b/toolkit/components/pictureinpicture/tests/browser_closePipPause.js
new file mode 100644
index 0000000000..b87888e411
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_closePipPause.js
@@ -0,0 +1,68 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * This test checks that MediaStream videos are not paused when closing
+ * the PiP window.
+ */
+add_task(async function test_close_mediaStreamVideos() {
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_ROOT + "test-media-stream.html",
+      gBrowser,
+    },
+    async browser => {
+      await SpecialPowers.spawn(browser, [], async () => {
+        // Construct a new video element, and capture a stream from it
+        // to redirect to both testing videos
+        let newVideo = content.document.createElement("video");
+        newVideo.src = "test-video.mp4";
+        newVideo.id = "media-stream-video";
+        content.document.body.appendChild(newVideo);
+        newVideo.loop = true;
+      });
+      await ensureVideosReady(browser);
+
+      // Modify both the "with-controls" and "no-controls" videos so that they mirror
+      // the new video that we just added via MediaStream.
+      await SpecialPowers.spawn(browser, [], async () => {
+        let newVideo = content.document.getElementById("media-stream-video");
+        newVideo.play();
+
+        for (let videoID of ["with-controls", "no-controls"]) {
+          let testedVideo = content.document.createElement("video");
+          testedVideo.id = videoID;
+          testedVideo.srcObject = newVideo.mozCaptureStream().clone();
+          content.document.body.prepend(testedVideo);
+          if (
+            testedVideo.readyState < content.HTMLMediaElement.HAVE_ENOUGH_DATA
+          ) {
+            info(`Waiting for 'canplaythrough' for '${testedVideo.id}'`);
+            await ContentTaskUtils.waitForEvent(testedVideo, "canplaythrough");
+          }
+          testedVideo.play();
+        }
+      });
+
+      for (let videoID of ["with-controls", "no-controls"]) {
+        let pipWin = await triggerPictureInPicture(browser, videoID);
+        ok(pipWin, "Got Picture-in-Picture window.");
+        ok(
+          !(await isVideoPaused(browser, videoID)),
+          "The video is not paused in PiP window."
+        );
+
+        let pipClosed = BrowserTestUtils.domWindowClosed(pipWin);
+        let closeButton = pipWin.document.getElementById("close");
+        EventUtils.synthesizeMouseAtCenter(closeButton, {}, pipWin);
+        await pipClosed;
+        ok(
+          !(await isVideoPaused(browser, videoID)),
+          "The video is not paused after closing PiP window."
+        );
+      }
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_closePip_pageNavigationChanges.js b/toolkit/components/pictureinpicture/tests/browser_closePip_pageNavigationChanges.js
new file mode 100644
index 0000000000..c64b5f2b14
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_closePip_pageNavigationChanges.js
@@ -0,0 +1,113 @@
+/* Any copyright is dedicated to the Public Domain.
+http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests that the pip window closes when the pagehide page lifecycle event
+ * is not detected and if a video is not loaded with a src.
+ */
+add_task(async function test_close_empty_pip_window() {
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE,
+      gBrowser,
+    },
+    async browser => {
+      let videoID = "with-controls";
+
+      await ensureVideosReady(browser);
+
+      let emptied = SpecialPowers.spawn(browser, [{ videoID }], async args => {
+        let video = content.document.getElementById(args.videoID);
+        info("Waiting for emptied event to be called");
+        await ContentTaskUtils.waitForEvent(video, "emptied");
+      });
+
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      let pipClosed = BrowserTestUtils.domWindowClosed(pipWin);
+      await SpecialPowers.spawn(browser, [{ videoID }], async args => {
+        let video = content.document.getElementById(args.videoID);
+        video.removeAttribute("src");
+        video.load();
+      });
+      await emptied;
+      await pipClosed;
+    }
+  );
+});
+
+/**
+ * Tests that the pip window closes when navigating to another page
+ * via the pagehide page lifecycle event.
+ */
+add_task(async function test_close_pagehide() {
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE,
+      gBrowser,
+    },
+    async browser => {
+      let videoID = "with-controls";
+
+      await ensureVideosReady(browser);
+      await SpecialPowers.spawn(browser, [{ videoID }], async args => {
+        let video = content.document.getElementById(args.videoID);
+        video.onemptied = () => {
+          // Since we handle pagehide first, handle emptied should not be invoked
+          ok(false, "emptied not expected to be called");
+        };
+      });
+
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      let pipClosed = BrowserTestUtils.domWindowClosed(pipWin);
+      await SpecialPowers.spawn(browser, [{ videoID }], async args => {
+        content.location.href = "otherpage.html";
+      });
+
+      await pipClosed;
+    }
+  );
+});
+
+/**
+ * Tests that the pip window remains open if the pagehide page lifecycle
+ * event is not detected and if the video is still loaded with a src.
+ */
+add_task(async function test_open_pip_window_history_nav() {
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE,
+      gBrowser,
+    },
+    async browser => {
+      let videoID = "with-controls";
+
+      await ensureVideosReady(browser);
+
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      await SpecialPowers.spawn(browser, [{ videoID }], async args => {
+        let popStatePromise = ContentTaskUtils.waitForEvent(
+          content,
+          "popstate"
+        );
+        content.history.pushState({}, "new page", "test-page-with-sound.html");
+        content.history.back();
+        await popStatePromise;
+      });
+
+      ok(!pipWin.closed, "pip windows should still be open");
+
+      let pipClosed = BrowserTestUtils.domWindowClosed(pipWin);
+      let closeButton = pipWin.document.getElementById("close");
+      EventUtils.synthesizeMouseAtCenter(closeButton, {}, pipWin);
+      await pipClosed;
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_closePlayer.js b/toolkit/components/pictureinpicture/tests/browser_closePlayer.js
new file mode 100644
index 0000000000..9b1b0a0047
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_closePlayer.js
@@ -0,0 +1,48 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests that closing with unpip leaves the video playing but the close button
+ * will pause the video.
+ */
+add_task(async () => {
+  for (let videoID of ["with-controls", "no-controls"]) {
+    info(`Testing ${videoID} case.`);
+
+    let playVideo = () => {
+      return SpecialPowers.spawn(browser, [videoID], async videoID => {
+        return content.document.getElementById(videoID).play();
+      });
+    };
+
+    let tab = await BrowserTestUtils.openNewForegroundTab(gBrowser, TEST_PAGE);
+    let browser = tab.linkedBrowser;
+    await playVideo();
+
+    // Try the unpip button.
+    let pipWin = await triggerPictureInPicture(browser, videoID);
+    ok(pipWin, "Got Picture-in-Picture window.");
+    ok(!(await isVideoPaused(browser, videoID)), "The video is not paused");
+
+    let pipClosed = BrowserTestUtils.domWindowClosed(pipWin);
+    let unpipButton = pipWin.document.getElementById("unpip");
+    EventUtils.synthesizeMouseAtCenter(unpipButton, {}, pipWin);
+    await pipClosed;
+    ok(!(await isVideoPaused(browser, videoID)), "The video is not paused");
+
+    // Try the close button.
+    pipWin = await triggerPictureInPicture(browser, videoID);
+    ok(pipWin, "Got Picture-in-Picture window.");
+    ok(!(await isVideoPaused(browser, videoID)), "The video is not paused");
+
+    pipClosed = BrowserTestUtils.domWindowClosed(pipWin);
+    let closeButton = pipWin.document.getElementById("close");
+    EventUtils.synthesizeMouseAtCenter(closeButton, {}, pipWin);
+    await pipClosed;
+    ok(await isVideoPaused(browser, videoID), "The video is paused");
+
+    BrowserTestUtils.removeTab(tab);
+  }
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_closeTab.js b/toolkit/components/pictureinpicture/tests/browser_closeTab.js
new file mode 100644
index 0000000000..e8c9f59d82
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_closeTab.js
@@ -0,0 +1,25 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests that if the tab that's hosting a <video> that's opened in a
+ * Picture-in-Picture window is closed, that the Picture-in-Picture
+ * window is also closed.
+ */
+add_task(async () => {
+  for (let videoID of ["with-controls", "no-controls"]) {
+    info(`Testing ${videoID} case.`);
+
+    let tab = await BrowserTestUtils.openNewForegroundTab(gBrowser, TEST_PAGE);
+    let browser = tab.linkedBrowser;
+
+    let pipWin = await triggerPictureInPicture(browser, videoID);
+    ok(pipWin, "Got Picture-in-Picture window.");
+
+    let pipClosed = BrowserTestUtils.domWindowClosed(pipWin);
+    BrowserTestUtils.removeTab(tab);
+    await pipClosed;
+  }
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_close_unpip_focus.js b/toolkit/components/pictureinpicture/tests/browser_close_unpip_focus.js
new file mode 100644
index 0000000000..f535add96a
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_close_unpip_focus.js
@@ -0,0 +1,72 @@
+/* Any copyright is dedicated to the Public Domain.
+http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Tests that closing a pip window will not focus on the originating video's window.
+add_task(async function test_close_button_focus() {
+  // initialize
+  let win1 = await BrowserTestUtils.openNewBrowserWindow();
+  let win2 = await BrowserTestUtils.openNewBrowserWindow();
+  // Open PiP
+  let videoID = "with-controls";
+  let pipTab = await BrowserTestUtils.openNewForegroundTab(
+    win1.gBrowser,
+    TEST_PAGE
+  );
+  let browser = pipTab.linkedBrowser;
+  let pipWin = await triggerPictureInPicture(browser, videoID);
+  ok(pipWin, "Got Picture-in-Picture window.");
+  let focus = BrowserTestUtils.waitForEvent(win2, "focus", true);
+  win2.focus();
+  await focus;
+
+  // Close PiP
+  let pipClosed = BrowserTestUtils.domWindowClosed(pipWin);
+  let closeButton = pipWin.document.getElementById("close");
+  let oldFocus = win1.focus;
+  win1.focus = () => {
+    ok(false, "Window is not supposed to be focused on");
+  };
+  EventUtils.synthesizeMouseAtCenter(closeButton, {}, pipWin);
+  await pipClosed;
+  ok(true, "Window did not get focus");
+
+  win1.focus = oldFocus;
+  // close windows
+  await BrowserTestUtils.closeWindow(win1);
+  await BrowserTestUtils.closeWindow(win2);
+});
+
+// Tests that pressing the unpip button will focus on the originating video's window.
+add_task(async function test_unpip_button_focus() {
+  // initialize
+  let win1 = await BrowserTestUtils.openNewBrowserWindow();
+  let win2 = await BrowserTestUtils.openNewBrowserWindow();
+  // Open PiP
+  let videoID = "with-controls";
+  let pipTab = await BrowserTestUtils.openNewForegroundTab(
+    win1.gBrowser,
+    TEST_PAGE
+  );
+  let browser = pipTab.linkedBrowser;
+  let pipWin = await triggerPictureInPicture(browser, videoID);
+  ok(pipWin, "Got Picture-in-Picture window.");
+  let focus = BrowserTestUtils.waitForEvent(win2, "focus", true);
+  win2.focus();
+  await focus;
+
+  // Close PiP
+  let pipClosed = BrowserTestUtils.domWindowClosed(pipWin);
+  let closeButton = pipWin.document.getElementById("unpip");
+  let pipWinFocusedPromise = BrowserTestUtils.waitForEvent(win1, "focus", true);
+  EventUtils.synthesizeMouseAtCenter(closeButton, {}, pipWin);
+
+  await pipClosed;
+  await pipWinFocusedPromise;
+  ok(true, "Originating window got focus");
+
+  // close windows
+  await BrowserTestUtils.closeWindow(win1);
+  await BrowserTestUtils.closeWindow(win2);
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_conflictingPips.js b/toolkit/components/pictureinpicture/tests/browser_conflictingPips.js
new file mode 100644
index 0000000000..cf9e27e327
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_conflictingPips.js
@@ -0,0 +1,46 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * If multiple PiPs try to open in the same place, they should not overlap.
+ */
+add_task(async () => {
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE,
+      gBrowser,
+    },
+    async browser => {
+      let firstPip = await triggerPictureInPicture(browser, "with-controls");
+      ok(firstPip, "Got first PiP window");
+
+      await ensureMessageAndClosePiP(browser, "with-controls", firstPip, false);
+      info("Closed first PiP to save location");
+
+      let secondPip = await triggerPictureInPicture(browser, "with-controls");
+      ok(secondPip, "Got second PiP window");
+
+      let thirdPip = await triggerPictureInPicture(browser, "no-controls");
+      ok(thirdPip, "Got third PiP window");
+
+      Assert.ok(
+        secondPip.screenX != thirdPip.screenX ||
+          secondPip.screenY != thirdPip.screenY,
+        "Conflicting PiPs were successfully opened in different locations"
+      );
+
+      await ensureMessageAndClosePiP(
+        browser,
+        "with-controls",
+        secondPip,
+        false
+      );
+      info("Second PiP was still open and is now closed");
+
+      await ensureMessageAndClosePiP(browser, "no-controls", thirdPip, false);
+      info("Third PiP was still open and is now closed");
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_contextMenu.js b/toolkit/components/pictureinpicture/tests/browser_contextMenu.js
new file mode 100644
index 0000000000..ce6a85e91c
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_contextMenu.js
@@ -0,0 +1,238 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Opens up the content area context menu on a video loaded in a
+ * browser.
+ *
+ * @param {Element} browser The <xul:browser> hosting the <video>
+ *
+ * @param {String} videoID The ID of the video to open the context
+ * menu with.
+ *
+ * @returns Promise
+ * @resolves With the context menu DOM node once opened.
+ */
+async function openContextMenu(browser, videoID) {
+  let contextMenu = document.getElementById("contentAreaContextMenu");
+  let popupShownPromise = BrowserTestUtils.waitForEvent(
+    contextMenu,
+    "popupshown"
+  );
+  await BrowserTestUtils.synthesizeMouseAtCenter(
+    "#" + videoID,
+    { type: "contextmenu", button: 2 },
+    browser
+  );
+  await popupShownPromise;
+  return contextMenu;
+}
+
+/**
+ * Closes the content area context menu.
+ *
+ * @param {Element} contextMenu The content area context menu opened with
+ * openContextMenu.
+ *
+ * @returns Promise
+ * @resolves With undefined
+ */
+async function closeContextMenu(contextMenu) {
+  let popupHiddenPromise = BrowserTestUtils.waitForEvent(
+    contextMenu,
+    "popuphidden"
+  );
+  contextMenu.hidePopup();
+  await popupHiddenPromise;
+}
+
+/**
+ * Tests that Picture-in-Picture can be opened and closed through the
+ * context menu
+ */
+add_task(async () => {
+  for (const videoId of ["with-controls", "no-controls"]) {
+    info(`Testing ${videoId} case.`);
+
+    await BrowserTestUtils.withNewTab(
+      {
+        url: TEST_PAGE,
+        gBrowser,
+      },
+      async browser => {
+        let contextMenu = await openContextMenu(browser, videoId);
+
+        info("Context menu is open.");
+
+        const pipMenuItemId = "context-video-pictureinpicture";
+        let menuItem = document.getElementById(pipMenuItemId);
+
+        Assert.ok(
+          !menuItem.hidden,
+          "Should show Picture-in-Picture menu item."
+        );
+        Assert.equal(
+          menuItem.getAttribute("checked"),
+          "false",
+          "Picture-in-Picture should be unchecked."
+        );
+
+        contextMenu.activateItem(menuItem);
+
+        await SpecialPowers.spawn(browser, [videoId], async videoID => {
+          let video = content.document.getElementById(videoID);
+          await ContentTaskUtils.waitForCondition(() => {
+            return video.isCloningElementVisually;
+          }, "Video has started being cloned.");
+        });
+
+        info("PiP player is now open.");
+
+        contextMenu = await openContextMenu(browser, videoId);
+
+        info("Context menu is open again.");
+
+        contextMenu.activateItem(menuItem);
+
+        await SpecialPowers.spawn(browser, [videoId], async videoID => {
+          let video = content.document.getElementById(videoID);
+          await ContentTaskUtils.waitForCondition(() => {
+            return !video.isCloningElementVisually;
+          }, "Video has stopped being cloned.");
+        });
+      }
+    );
+  }
+});
+
+/**
+ * Tests that the Picture-in-Picture context menu is correctly updated
+ * based on the Picture-in-Picture state of the video.
+ */
+add_task(async () => {
+  for (let videoID of ["with-controls", "no-controls"]) {
+    info(`Testing ${videoID} case.`);
+
+    await BrowserTestUtils.withNewTab(
+      {
+        url: TEST_PAGE,
+        gBrowser,
+      },
+      async browser => {
+        let menuItem = document.getElementById(
+          "context-video-pictureinpicture"
+        );
+        let menu = await openContextMenu(browser, videoID);
+        Assert.ok(
+          !menuItem.hidden,
+          "Should show Picture-in-Picture menu item."
+        );
+        Assert.equal(
+          menuItem.getAttribute("checked"),
+          "false",
+          "Picture-in-Picture should be unchecked."
+        );
+        await closeContextMenu(menu);
+
+        let pipWin = await triggerPictureInPicture(browser, videoID);
+        ok(pipWin, "Got Picture-in-Picture window.");
+
+        await SpecialPowers.spawn(browser, [videoID], async videoID => {
+          let video = content.document.getElementById(videoID);
+          await ContentTaskUtils.waitForCondition(() => {
+            return video.isCloningElementVisually;
+          }, "Video has started being cloned.");
+        });
+
+        menu = await openContextMenu(browser, videoID);
+        Assert.ok(
+          !menuItem.hidden,
+          "Should show Picture-in-Picture menu item."
+        );
+        Assert.equal(
+          menuItem.getAttribute("checked"),
+          "true",
+          "Picture-in-Picture should be checked."
+        );
+        await closeContextMenu(menu);
+
+        let videoNotCloning = SpecialPowers.spawn(
+          browser,
+          [videoID],
+          async videoID => {
+            let video = content.document.getElementById(videoID);
+            await ContentTaskUtils.waitForCondition(() => {
+              return !video.isCloningElementVisually;
+            }, "Video has stopped being cloned.");
+          }
+        );
+        pipWin.close();
+        await videoNotCloning;
+
+        menu = await openContextMenu(browser, videoID);
+        Assert.ok(
+          !menuItem.hidden,
+          "Should show Picture-in-Picture menu item."
+        );
+        Assert.equal(
+          menuItem.getAttribute("checked"),
+          "false",
+          "Picture-in-Picture should be unchecked."
+        );
+        await closeContextMenu(menu);
+
+        await SpecialPowers.spawn(browser, [videoID], async videoID => {
+          // Construct a new video element, and capture a stream from it
+          // to redirect to the video that we're testing.
+          let newVideo = content.document.createElement("video");
+          content.document.body.appendChild(newVideo);
+
+          let testedVideo = content.document.getElementById(videoID);
+          newVideo.src = testedVideo.src;
+
+          testedVideo.srcObject = newVideo.mozCaptureStream();
+          await newVideo.play();
+          await testedVideo.play();
+
+          await newVideo.pause();
+          await testedVideo.pause();
+        });
+        menu = await openContextMenu(browser, videoID);
+        Assert.ok(
+          !menuItem.hidden,
+          "Should be showing Picture-in-Picture menu item."
+        );
+        Assert.equal(
+          menuItem.getAttribute("checked"),
+          "false",
+          "Picture-in-Picture should be unchecked."
+        );
+        await closeContextMenu(menu);
+
+        pipWin = await triggerPictureInPicture(browser, videoID);
+        ok(pipWin, "Got Picture-in-Picture window.");
+
+        await SpecialPowers.spawn(browser, [videoID], async videoID => {
+          let video = content.document.getElementById(videoID);
+          await ContentTaskUtils.waitForCondition(() => {
+            return video.isCloningElementVisually;
+          }, "Video has started being cloned.");
+        });
+
+        menu = await openContextMenu(browser, videoID);
+        Assert.ok(
+          !menuItem.hidden,
+          "Should show Picture-in-Picture menu item."
+        );
+        Assert.equal(
+          menuItem.getAttribute("checked"),
+          "true",
+          "Picture-in-Picture should be checked."
+        );
+        await closeContextMenu(menu);
+      }
+    );
+  }
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_controlsHover.js b/toolkit/components/pictureinpicture/tests/browser_controlsHover.js
new file mode 100644
index 0000000000..7a3a33733f
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_controlsHover.js
@@ -0,0 +1,191 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests functionality for the hover states of the various controls for the Picture-in-Picture
+ * video window.
+ */
+add_task(async () => {
+  let videoID = "with-controls";
+
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE,
+      gBrowser,
+    },
+    async browser => {
+      let waitForVideoEvent = eventType => {
+        return BrowserTestUtils.waitForContentEvent(browser, eventType, true);
+      };
+
+      await ensureVideosReady(browser);
+      await SpecialPowers.spawn(browser, [videoID], async videoID => {
+        await content.document.getElementById(videoID).play();
+      });
+
+      // Open the video in PiP
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      const l10n = new Localization(
+        ["toolkit/pictureinpicture/pictureinpicture.ftl"],
+        true
+      );
+
+      let [
+        close,
+        play,
+        unmute,
+        unpip,
+        subtitles,
+        pause,
+        mute,
+        fullscreenEnter,
+        fullscreenExit,
+      ] = l10n.formatMessagesSync([
+        {
+          id: "pictureinpicture-close-btn",
+          args: {
+            shortcut: ShortcutUtils.prettifyShortcut(
+              pipWin.document.getElementById("closeShortcut")
+            ),
+          },
+        },
+        { id: "pictureinpicture-play-btn" },
+        {
+          id: "pictureinpicture-unmute-btn",
+          args: {
+            shortcut: ShortcutUtils.prettifyShortcut(
+              pipWin.document.getElementById("unMuteShortcut")
+            ),
+          },
+        },
+        { id: "pictureinpicture-unpip-btn" },
+        { id: "pictureinpicture-subtitles-btn" },
+        { id: "pictureinpicture-pause-btn" },
+        {
+          id: "pictureinpicture-mute-btn",
+          args: {
+            shortcut: ShortcutUtils.prettifyShortcut(
+              pipWin.document.getElementById("muteShortcut")
+            ),
+          },
+        },
+        {
+          id: "pictureinpicture-fullscreen-btn2",
+          args: {
+            shortcut: ShortcutUtils.prettifyShortcut(
+              pipWin.document.getElementById("fullscreenToggleShortcut")
+            ),
+          },
+        },
+        {
+          id: "pictureinpicture-exit-fullscreen-btn2",
+          args: {
+            shortcut: ShortcutUtils.prettifyShortcut(
+              pipWin.document.getElementById("fullscreenToggleShortcut")
+            ),
+          },
+        },
+      ]);
+
+      let closeButton = pipWin.document.getElementById("close");
+      let playPauseButton = pipWin.document.getElementById("playpause");
+      let unpipButton = pipWin.document.getElementById("unpip");
+      let muteUnmuteButton = pipWin.document.getElementById("audio");
+      let subtitlesButton = pipWin.document.getElementById("closed-caption");
+      let fullscreenButton = pipWin.document.getElementById("fullscreen");
+
+      // checks hover title for close button
+      await pipWin.document.l10n.translateFragment(closeButton);
+      Assert.equal(
+        close.attributes[1].value,
+        closeButton.getAttribute("tooltip"),
+        "The close button title matches Fluent string"
+      );
+
+      // checks hover title for play button
+      await pipWin.document.l10n.translateFragment(playPauseButton);
+      Assert.equal(
+        pause.attributes[1].value,
+        playPauseButton.getAttribute("tooltip"),
+        "The play button title matches Fluent string"
+      );
+
+      // checks hover title for unpip button
+      await pipWin.document.l10n.translateFragment(unpipButton);
+      Assert.equal(
+        unpip.attributes[1].value,
+        unpipButton.getAttribute("tooltip"),
+        "The unpip button title matches Fluent string"
+      );
+
+      // checks hover title for subtitles button
+      await pipWin.document.l10n.translateFragment(subtitlesButton);
+      Assert.equal(
+        subtitles.attributes[1].value,
+        subtitlesButton.getAttribute("tooltip"),
+        "The subtitles button title matches Fluent string"
+      );
+
+      // checks hover title for unmute button
+      await pipWin.document.l10n.translateFragment(muteUnmuteButton);
+      Assert.equal(
+        mute.attributes[1].value,
+        muteUnmuteButton.getAttribute("tooltip"),
+        "The Unmute button title matches Fluent string"
+      );
+
+      // Pause the video
+      let pausedPromise = waitForVideoEvent("pause");
+      EventUtils.synthesizeMouseAtCenter(playPauseButton, {}, pipWin);
+      await pausedPromise;
+      ok(await isVideoPaused(browser, videoID), "The video is paused.");
+
+      // checks hover title for pause button
+      await pipWin.document.l10n.translateFragment(playPauseButton);
+      Assert.equal(
+        play.attributes[1].value,
+        playPauseButton.getAttribute("tooltip"),
+        "The pause button title matches Fluent string"
+      );
+
+      // Mute the video
+      let mutedPromise = waitForVideoEvent("volumechange");
+      EventUtils.synthesizeMouseAtCenter(muteUnmuteButton, {}, pipWin);
+      await mutedPromise;
+      ok(await isVideoMuted(browser, videoID), "The audio is muted.");
+
+      // checks hover title for mute button
+      await pipWin.document.l10n.translateFragment(muteUnmuteButton);
+      Assert.equal(
+        unmute.attributes[1].value,
+        muteUnmuteButton.getAttribute("tooltip"),
+        "The mute button title matches Fluent string"
+      );
+
+      // checks hover title for enter fullscreen button
+      await pipWin.document.l10n.translateFragment(fullscreenButton);
+      Assert.equal(
+        fullscreenEnter.attributes[1].value,
+        fullscreenButton.getAttribute("tooltip"),
+        "The enter fullscreen button title matches Fluent string"
+      );
+
+      // enable fullscreen
+      await promiseFullscreenEntered(pipWin, async () => {
+        EventUtils.synthesizeMouseAtCenter(fullscreenButton, {}, pipWin);
+      });
+
+      // checks hover title for exit fullscreen button
+      await pipWin.document.l10n.translateFragment(fullscreenButton);
+      Assert.equal(
+        fullscreenExit.attributes[1].value,
+        fullscreenButton.getAttribute("tooltip"),
+        "The exit fullscreen button title matches Fluent string"
+      );
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_cornerSnapping.js b/toolkit/components/pictureinpicture/tests/browser_cornerSnapping.js
new file mode 100644
index 0000000000..7ebfafc721
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_cornerSnapping.js
@@ -0,0 +1,271 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+const FLOAT_OFFSET = 50;
+const CHANGE_OFFSET = 30;
+const DECREASE_OFFSET = FLOAT_OFFSET - CHANGE_OFFSET;
+const INCREASE_OFFSET = FLOAT_OFFSET + CHANGE_OFFSET;
+/**
+ * This function tests the PiP corner snapping feature.
+ */
+add_task(async () => {
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: TEST_PAGE,
+    },
+    async browser => {
+      let pipWin = await triggerPictureInPicture(browser, "no-controls");
+      let controls = pipWin.document.getElementById("controls");
+
+      /**
+       * pipWin floating in top left corner(quadrant 2), dragged left
+       * should snap into top left corner
+       */
+      pipWin.moveTo(
+        pipWin.screen.availLeft + FLOAT_OFFSET,
+        pipWin.screen.availTop + FLOAT_OFFSET
+      );
+      EventUtils.sendMouseEvent({ type: "mouseup" }, controls, pipWin);
+      pipWin.moveTo(
+        pipWin.screen.availLeft + DECREASE_OFFSET,
+        pipWin.screen.availTop + FLOAT_OFFSET
+      );
+      EventUtils.sendMouseEvent(
+        {
+          type: "mouseup",
+          metaKey: true,
+        },
+        controls,
+        pipWin
+      );
+      Assert.equal(
+        pipWin.screenX,
+        pipWin.screen.availLeft,
+        "Window should be on the left"
+      );
+      Assert.equal(
+        pipWin.screenY,
+        pipWin.screen.availTop,
+        "Window should be on the top"
+      );
+
+      /**
+       * pipWin floating in top left corner(quadrant 2), dragged up
+       * should snap into top left corner
+       */
+      pipWin.moveTo(
+        pipWin.screen.availLeft + FLOAT_OFFSET,
+        pipWin.screen.availTop + FLOAT_OFFSET
+      );
+      EventUtils.sendMouseEvent({ type: "mouseup" }, controls, pipWin);
+      pipWin.moveTo(
+        pipWin.screen.availLeft + FLOAT_OFFSET,
+        pipWin.screen.availTop + DECREASE_OFFSET
+      );
+      EventUtils.sendMouseEvent(
+        {
+          type: "mouseup",
+          metaKey: true,
+        },
+        controls,
+        pipWin
+      );
+      Assert.equal(
+        pipWin.screenX,
+        pipWin.screen.availLeft,
+        "Window should be on the left"
+      );
+      Assert.equal(
+        pipWin.screenY,
+        pipWin.screen.availTop,
+        "Window should be on the top"
+      );
+
+      /**
+       * pipWin floating in top left corner(quadrant 2), dragged right
+       * should snap into top right corner
+       */
+      pipWin.moveTo(
+        pipWin.screen.availLeft + FLOAT_OFFSET,
+        pipWin.screen.availTop + FLOAT_OFFSET
+      );
+      EventUtils.sendMouseEvent({ type: "mouseup" }, controls, pipWin);
+      pipWin.moveTo(
+        pipWin.screen.availLeft + INCREASE_OFFSET,
+        pipWin.screen.availTop + FLOAT_OFFSET
+      );
+      EventUtils.sendMouseEvent(
+        {
+          type: "mouseup",
+          metaKey: true,
+        },
+        controls,
+        pipWin
+      );
+      Assert.equal(
+        pipWin.screenX,
+        pipWin.screen.availLeft + pipWin.screen.availWidth - pipWin.innerWidth,
+        "Window should be on the right"
+      );
+      Assert.equal(
+        pipWin.screenY,
+        pipWin.screen.availTop,
+        "Window should be on the top"
+      );
+
+      /**
+       * pipWin floating in top left corner(quadrant 2), dragged down
+       * should snap into bottom left corner
+       */
+      pipWin.moveTo(
+        pipWin.screen.availLeft + FLOAT_OFFSET,
+        pipWin.screen.availTop + FLOAT_OFFSET
+      );
+      EventUtils.sendMouseEvent({ type: "mouseup" }, controls, pipWin);
+      pipWin.moveTo(
+        pipWin.screen.availLeft + FLOAT_OFFSET,
+        pipWin.screen.availTop + INCREASE_OFFSET
+      );
+      EventUtils.sendMouseEvent(
+        {
+          type: "mouseup",
+          metaKey: true,
+        },
+        controls,
+        pipWin
+      );
+      Assert.equal(
+        pipWin.screenX,
+        pipWin.screen.availLeft,
+        "Window should be on the left"
+      );
+      Assert.equal(
+        pipWin.screenY,
+        pipWin.screen.availTop + pipWin.screen.availHeight - pipWin.innerHeight,
+        "Window should be on the bottom"
+      );
+
+      /**
+       * pipWin floating in top right corner(quadrant 1), dragged down
+       * should snap into bottom right corner
+       */
+      pipWin.moveTo(
+        pipWin.screen.availLeft +
+          pipWin.screen.availWidth -
+          pipWin.innerWidth -
+          FLOAT_OFFSET,
+        pipWin.screen.availTop + FLOAT_OFFSET
+      );
+      EventUtils.sendMouseEvent({ type: "mouseup" }, controls, pipWin);
+      pipWin.moveTo(
+        pipWin.screen.availLeft +
+          pipWin.screen.availWidth -
+          pipWin.innerWidth -
+          FLOAT_OFFSET,
+        pipWin.screen.availTop + INCREASE_OFFSET
+      );
+      EventUtils.sendMouseEvent(
+        {
+          type: "mouseup",
+          metaKey: true,
+        },
+        controls,
+        pipWin
+      );
+      Assert.equal(
+        pipWin.screenX,
+        pipWin.screen.availLeft + pipWin.screen.availWidth - pipWin.innerWidth,
+        "Window should be on the right"
+      );
+      Assert.equal(
+        pipWin.screenY,
+        pipWin.screen.availTop + pipWin.screen.availHeight - pipWin.innerHeight,
+        "Window should be on the bottom"
+      );
+
+      /**
+       * pipWin floating in top left corner(quadrant 4), dragged left
+       * should snap into bottom left corner
+       */
+      pipWin.moveTo(
+        pipWin.screen.availLeft +
+          pipWin.screen.availWidth -
+          pipWin.innerWidth -
+          FLOAT_OFFSET,
+        pipWin.screen.availTop +
+          pipWin.screen.availHeight -
+          pipWin.innerHeight -
+          FLOAT_OFFSET
+      );
+      EventUtils.sendMouseEvent({ type: "mouseup" }, controls, pipWin);
+      pipWin.moveTo(
+        pipWin.screen.availLeft +
+          pipWin.screen.availWidth -
+          pipWin.innerWidth -
+          INCREASE_OFFSET,
+        pipWin.screen.availTop +
+          pipWin.screen.availHeight -
+          pipWin.innerHeight -
+          FLOAT_OFFSET
+      );
+      EventUtils.sendMouseEvent(
+        {
+          type: "mouseup",
+          metaKey: true,
+        },
+        controls,
+        pipWin
+      );
+      Assert.equal(
+        pipWin.screenX,
+        pipWin.screen.availLeft,
+        "Window should be on the left"
+      );
+      Assert.equal(
+        pipWin.screenY,
+        pipWin.screen.availTop + pipWin.screen.availHeight - pipWin.innerHeight,
+        "Window should be on the bottom"
+      );
+
+      /**
+       * pipWin floating in top left corner(quadrant 3), dragged up
+       * should snap into top left corner
+       */
+      pipWin.moveTo(
+        pipWin.screen.availLeft + FLOAT_OFFSET,
+        pipWin.screen.availTop +
+          pipWin.screen.availHeight -
+          pipWin.innerHeight -
+          FLOAT_OFFSET
+      );
+      EventUtils.sendMouseEvent({ type: "mouseup" }, controls, pipWin);
+      pipWin.moveTo(
+        pipWin.screen.availLeft + FLOAT_OFFSET,
+        pipWin.screen.availTop +
+          pipWin.screen.availHeight -
+          pipWin.innerHeight -
+          INCREASE_OFFSET
+      );
+      EventUtils.sendMouseEvent(
+        {
+          type: "mouseup",
+          metaKey: true,
+        },
+        controls,
+        pipWin
+      );
+      Assert.equal(
+        pipWin.screenX,
+        pipWin.screen.availLeft,
+        "Window should be on the left"
+      );
+      Assert.equal(
+        pipWin.screenY,
+        pipWin.screen.availTop,
+        "Window should be on the top"
+      );
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_dblclickFullscreen.js b/toolkit/components/pictureinpicture/tests/browser_dblclickFullscreen.js
new file mode 100644
index 0000000000..c30d316fe3
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_dblclickFullscreen.js
@@ -0,0 +1,101 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests that double-clicking on the Picture-in-Picture player window
+ * causes it to fullscreen, and that pressing Escape allows us to exit
+ * fullscreen.
+ */
+add_task(async () => {
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: TEST_PAGE,
+    },
+    async browser => {
+      let pipWin = await triggerPictureInPicture(browser, "no-controls");
+      let controls = pipWin.document.getElementById("controls");
+
+      await promiseFullscreenEntered(pipWin, async () => {
+        EventUtils.sendMouseEvent(
+          {
+            type: "dblclick",
+          },
+          controls,
+          pipWin
+        );
+      });
+
+      Assert.equal(
+        pipWin.document.fullscreenElement,
+        pipWin.document.body,
+        "Double-click caused us to enter fullscreen."
+      );
+
+      await BrowserTestUtils.waitForCondition(
+        () => {
+          let close = pipWin.document.getElementById("close");
+          let opacity = parseFloat(pipWin.getComputedStyle(close).opacity);
+          return opacity == 0.0;
+        },
+        "Close button in player should have reached 0.0 opacity",
+        100,
+        100
+      );
+
+      // First, we'll test exiting fullscreen by double-clicking again
+      // on the document body.
+
+      await promiseFullscreenExited(pipWin, async () => {
+        EventUtils.sendMouseEvent(
+          {
+            type: "dblclick",
+          },
+          controls,
+          pipWin
+        );
+      });
+
+      Assert.ok(
+        !pipWin.document.fullscreenElement,
+        "Double-click caused us to exit fullscreen."
+      );
+
+      // Now we double-click to re-enter fullscreen.
+
+      await promiseFullscreenEntered(pipWin, async () => {
+        EventUtils.sendMouseEvent(
+          {
+            type: "dblclick",
+          },
+          controls,
+          pipWin
+        );
+      });
+
+      Assert.equal(
+        pipWin.document.fullscreenElement,
+        pipWin.document.body,
+        "Double-click caused us to re-enter fullscreen."
+      );
+
+      // Finally, we check that hitting Escape lets the user leave
+      // fullscreen.
+
+      await promiseFullscreenExited(pipWin, async () => {
+        EventUtils.synthesizeKey("KEY_Escape", {}, pipWin);
+      });
+
+      Assert.ok(
+        !pipWin.document.fullscreenElement,
+        "Pressing Escape caused us to exit fullscreen."
+      );
+
+      let pipClosed = BrowserTestUtils.domWindowClosed(pipWin);
+      pipWin.close();
+      await pipClosed;
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_durationChange.js b/toolkit/components/pictureinpicture/tests/browser_durationChange.js
new file mode 100644
index 0000000000..69397d8959
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_durationChange.js
@@ -0,0 +1,61 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests that the visibility of the toggle will be
+ * recomputed after durationchange events fire.
+ */
+add_task(async function test_durationChange() {
+  // Most of the Picture-in-Picture tests run with the always-show
+  // preference set to true to avoid the toggle visibility heuristics.
+  // Since this test actually exercises those heuristics, we have
+  // to temporarily disable that pref.
+  //
+  // We also reduce the minimum video length for displaying the toggle
+  // to 5 seconds to avoid having to include or generate a 45 second long
+  // video (which is the default minimum length).
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      [
+        "media.videocontrols.picture-in-picture.video-toggle.always-show",
+        false,
+      ],
+      ["media.videocontrols.picture-in-picture.video-toggle.min-video-secs", 5],
+    ],
+  });
+
+  // First, ensure that the toggle doesn't show up for these
+  // short videos by default.
+  await testToggle(TEST_PAGE, {
+    "with-controls": { canToggle: false },
+    "no-controls": { canToggle: false },
+  });
+
+  // Now cause the video to change sources, which should fire a
+  // durationchange event. The longer video should qualify us for
+  // displaying the toggle.
+  await testToggle(
+    TEST_PAGE,
+    {
+      "with-controls": { canToggle: true },
+      "no-controls": { canToggle: true },
+    },
+    async browser => {
+      await SpecialPowers.spawn(browser, [], async () => {
+        for (let videoID of ["with-controls", "no-controls"]) {
+          let video = content.document.getElementById(videoID);
+          video.src = "gizmo.mp4";
+          let durationChangePromise = ContentTaskUtils.waitForEvent(
+            video,
+            "durationchange"
+          );
+
+          video.load();
+          await durationChangePromise;
+        }
+      });
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_flipIconWithRTL.js b/toolkit/components/pictureinpicture/tests/browser_flipIconWithRTL.js
new file mode 100644
index 0000000000..cfb91440f5
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_flipIconWithRTL.js
@@ -0,0 +1,66 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * The goal of this test is to check that the icon on the PiP button mirrors
+ * and the explainer text that shows up before the first time PiP is used
+ * right aligns when the browser is set to a RtL mode
+ *
+ * The browser will create a tab and open a video using PiP
+ * then the tests check that the components change their appearance accordingly
+ *
+ */
+
+/**
+ * This test ensures that the default ltr is working as intended
+ */
+add_task(async function test_ltr_toggle() {
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: TEST_PAGE,
+    },
+    async browser => {
+      await ensureVideosReady(browser);
+      for (let videoId of ["with-controls", "no-controls"]) {
+        let localeDir = await SpecialPowers.spawn(browser, [videoId], id => {
+          let video = content.document.getElementById(id);
+          let videocontrols = video.openOrClosedShadowRoot.firstChild;
+          return videocontrols.getAttribute("localedir");
+        });
+
+        Assert.equal(localeDir, "ltr", "Got the right localedir");
+      }
+    }
+  );
+});
+
+/**
+ * This test ensures that the components flip correctly when rtl is set
+ */
+add_task(async function test_rtl_toggle() {
+  await SpecialPowers.pushPrefEnv({
+    set: [["intl.l10n.pseudo", "bidi"]],
+  });
+
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: TEST_PAGE,
+    },
+    async browser => {
+      await ensureVideosReady(browser);
+      for (let videoId of ["with-controls", "no-controls"]) {
+        let localeDir = await SpecialPowers.spawn(browser, [videoId], id => {
+          let video = content.document.getElementById(id);
+          let videocontrols = video.openOrClosedShadowRoot.firstChild;
+          return videocontrols.getAttribute("localedir");
+        });
+
+        Assert.equal(localeDir, "rtl", "Got the right localedir");
+      }
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_fontSize_change.js b/toolkit/components/pictureinpicture/tests/browser_fontSize_change.js
new file mode 100644
index 0000000000..df0fa4f403
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_fontSize_change.js
@@ -0,0 +1,152 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const videoID = "with-controls";
+const TEXT_TRACK_FONT_SIZE =
+  "media.videocontrols.picture-in-picture.display-text-tracks.size";
+const ACCEPTABLE_DIFF = 1;
+
+const checkFontSize = (actual, expected, str) => {
+  let fs1 = actual.substring(0, actual.length - 2);
+  let fs2 = expected;
+  let diff = Math.abs(fs1 - fs2);
+  info(`Actual font size: ${fs1}. Expected font size: ${fs2}`);
+  Assert.lessOrEqual(diff, ACCEPTABLE_DIFF, str);
+};
+
+function getFontSize(pipBrowser) {
+  return SpecialPowers.spawn(pipBrowser, [], async () => {
+    info("Checking text track content in pip window");
+    let textTracks = content.document.getElementById("texttracks");
+    ok(textTracks, "TextTracks container should exist in the pip window");
+    await ContentTaskUtils.waitForCondition(() => {
+      return textTracks.textContent;
+    }, `Text track is still not visible on the pip window. Got ${textTracks.textContent}`);
+    return content.window.getComputedStyle(textTracks).fontSize;
+  });
+}
+
+function promiseResize(win, width, height) {
+  if (win.outerWidth == width && win.outerHeight == height) {
+    return Promise.resolve();
+  }
+  return new Promise(resolve => {
+    // More than one "resize" might be received if the window was recently
+    // created.
+    win.addEventListener("resize", () => {
+      if (win.outerWidth == width && win.outerHeight == height) {
+        resolve();
+      }
+    });
+    win.resizeTo(width, height);
+  });
+}
+
+/**
+ * Tests the font size is correct for PiP windows
+ */
+add_task(async () => {
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      [
+        "media.videocontrols.picture-in-picture.display-text-tracks.enabled",
+        true,
+      ],
+    ],
+  });
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: TEST_PAGE_WITH_WEBVTT,
+    },
+    async browser => {
+      await prepareVideosAndWebVTTTracks(browser, videoID);
+
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      // move PiP window to 0, 0 so resizing the window doesn't go offscreen
+      pipWin.moveTo(0, 0);
+
+      let width = pipWin.innerWidth;
+      let height = pipWin.innerHeight;
+
+      await promiseResize(pipWin, Math.round(250 * (width / height)), 250);
+
+      width = pipWin.innerWidth;
+      height = pipWin.innerHeight;
+
+      let pipBrowser = pipWin.document.getElementById("browser");
+
+      let fontSize = await getFontSize(pipBrowser);
+      checkFontSize(
+        fontSize,
+        Math.round(height * 0.06 * 10) / 10,
+        "The medium font size is .06 of the PiP window height"
+      );
+
+      await ensureMessageAndClosePiP(browser, videoID, pipWin, false);
+
+      // change font size to small
+      await SpecialPowers.pushPrefEnv({
+        set: [[TEXT_TRACK_FONT_SIZE, "small"]],
+      });
+
+      pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      pipBrowser = pipWin.document.getElementById("browser");
+
+      fontSize = await getFontSize(pipBrowser);
+      checkFontSize(fontSize, 14, "The small font size is the minimum 14px");
+
+      await ensureMessageAndClosePiP(browser, videoID, pipWin, false);
+
+      // change font size to large
+      await SpecialPowers.pushPrefEnv({
+        set: [[TEXT_TRACK_FONT_SIZE, "large"]],
+      });
+
+      pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      pipBrowser = pipWin.document.getElementById("browser");
+
+      fontSize = await getFontSize(pipBrowser);
+      checkFontSize(
+        fontSize,
+        Math.round(height * 0.09 * 10) / 10,
+        "The large font size is .09 of the PiP window height"
+      );
+
+      // resize PiP window to a larger size
+      width = pipWin.innerWidth * 2;
+      height = pipWin.innerHeight * 2;
+      await promiseResize(pipWin, width, height);
+
+      fontSize = await getFontSize(pipBrowser);
+      checkFontSize(fontSize, 40, "The large font size is the max of 40px");
+
+      await ensureMessageAndClosePiP(browser, videoID, pipWin, false);
+
+      // change font size to small
+      await SpecialPowers.pushPrefEnv({
+        set: [[TEXT_TRACK_FONT_SIZE, "small"]],
+      });
+
+      pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      pipBrowser = pipWin.document.getElementById("browser");
+
+      fontSize = await getFontSize(pipBrowser);
+      checkFontSize(
+        fontSize,
+        Math.round(height * 0.03 * 10) / 10,
+        "The small font size is .03 of the PiP window height"
+      );
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_fullscreen.js b/toolkit/components/pictureinpicture/tests/browser_fullscreen.js
new file mode 100644
index 0000000000..5f80c56307
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_fullscreen.js
@@ -0,0 +1,142 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const VIDEOS = ["with-controls", "no-controls"];
+
+/**
+ * Tests that the Picture-in-Picture toggle is hidden when
+ * a video with or without controls is made fullscreen.
+ */
+add_task(async () => {
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: TEST_PAGE,
+    },
+    async browser => {
+      for (let videoID of VIDEOS) {
+        await promiseFullscreenEntered(window, async () => {
+          await SpecialPowers.spawn(browser, [videoID], async videoID => {
+            let video = this.content.document.getElementById(videoID);
+            video.requestFullscreen();
+          });
+        });
+
+        await BrowserTestUtils.synthesizeMouseAtCenter(
+          `#${videoID}`,
+          {
+            type: "mouseover",
+          },
+          browser
+        );
+
+        let args = { videoID, toggleID: DEFAULT_TOGGLE_STYLES.rootID };
+
+        await promiseFullscreenExited(window, async () => {
+          await SpecialPowers.spawn(browser, [args], async args => {
+            let { videoID, toggleID } = args;
+            let video = this.content.document.getElementById(videoID);
+            let toggle = video.openOrClosedShadowRoot.getElementById(toggleID);
+            ok(
+              ContentTaskUtils.is_hidden(toggle),
+              "Toggle should be hidden in fullscreen mode."
+            );
+            this.content.document.exitFullscreen();
+          });
+        });
+      }
+    }
+  );
+});
+
+/**
+ * Tests that the Picture-in-Picture toggle is hidden if an
+ * ancestor of a video (in this case, the document body) is made
+ * to be the fullscreen element.
+ */
+add_task(async () => {
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: TEST_PAGE,
+    },
+    async browser => {
+      await promiseFullscreenEntered(window, async () => {
+        await SpecialPowers.spawn(browser, [], async () => {
+          this.content.document.body.requestFullscreen();
+        });
+      });
+
+      for (let videoID of VIDEOS) {
+        await BrowserTestUtils.synthesizeMouseAtCenter(
+          `#${videoID}`,
+          {
+            type: "mouseover",
+          },
+          browser
+        );
+
+        let args = { videoID, toggleID: DEFAULT_TOGGLE_STYLES.rootID };
+
+        await SpecialPowers.spawn(browser, [args], async args => {
+          let { videoID, toggleID } = args;
+          let video = this.content.document.getElementById(videoID);
+          let toggle = video.openOrClosedShadowRoot.getElementById(toggleID);
+          ok(
+            ContentTaskUtils.is_hidden(toggle),
+            "Toggle should be hidden in fullscreen mode."
+          );
+        });
+      }
+
+      await promiseFullscreenExited(window, async () => {
+        await SpecialPowers.spawn(browser, [], async () => {
+          this.content.document.exitFullscreen();
+        });
+      });
+    }
+  );
+});
+
+/**
+ * Tests that the Picture-In-Picture window is closed when something
+ * is fullscreened
+ */
+add_task(async () => {
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: TEST_PAGE,
+    },
+    async browser => {
+      await ensureVideosReady(browser);
+
+      for (let videoId of VIDEOS) {
+        let pipWin = await triggerPictureInPicture(browser, videoId);
+        ok(pipWin, "Got Picture-In-Picture window.");
+
+        let pipClosed = BrowserTestUtils.domWindowClosed(pipWin);
+
+        // need to focus first, since fullscreen request will be blocked otherwise
+        await SimpleTest.promiseFocus(window);
+
+        await promiseFullscreenEntered(window, async () => {
+          await SpecialPowers.spawn(browser, [], async () => {
+            this.content.document.body.requestFullscreen();
+          });
+        });
+
+        await pipClosed;
+        ok(pipWin.closed, "Picture-In-Picture successfully closed.");
+
+        await promiseFullscreenExited(window, async () => {
+          await SpecialPowers.spawn(browser, [], async () => {
+            this.content.document.exitFullscreen();
+          });
+        });
+      }
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_improved_controls.js b/toolkit/components/pictureinpicture/tests/browser_improved_controls.js
new file mode 100644
index 0000000000..deadc8d53b
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_improved_controls.js
@@ -0,0 +1,303 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { TelemetryTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/TelemetryTestUtils.sys.mjs"
+);
+
+const TEST_PAGE_LONG = TEST_ROOT + "test-video-selection.html";
+
+const IMPROVED_CONTROLS_ENABLED_PREF =
+  "media.videocontrols.picture-in-picture.improved-video-controls.enabled";
+
+async function getVideoCurrentTime(browser, videoID) {
+  return SpecialPowers.spawn(browser, [videoID], async videoID => {
+    return content.document.getElementById(videoID).currentTime;
+  });
+}
+
+async function getVideoDuration(browser, videoID) {
+  return SpecialPowers.spawn(browser, [videoID], async videoID => {
+    return content.document.getElementById(videoID).duration;
+  });
+}
+
+async function timestampUpdated(timestampEl, expectedTimestamp) {
+  await BrowserTestUtils.waitForMutationCondition(
+    timestampEl,
+    { childList: true },
+    () => {
+      return expectedTimestamp === timestampEl.textContent;
+    }
+  );
+}
+
+function checkTimeCloseEnough(actual, expected, message) {
+  let equal = Math.abs(actual - expected);
+  if (equal <= 0.5) {
+    is(equal <= 0.5, true, message);
+  } else {
+    is(actual, expected, message);
+  }
+}
+
+/**
+ * Tests the functionality of improved Picture-in-picture
+ * playback controls.
+ */
+add_task(async () => {
+  let videoID = "with-controls";
+
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE,
+      gBrowser,
+    },
+    async browser => {
+      let waitForVideoEvent = eventType => {
+        return BrowserTestUtils.waitForContentEvent(browser, eventType, true);
+      };
+
+      await ensureVideosReady(browser);
+      await SpecialPowers.spawn(browser, [videoID], async videoID => {
+        await content.document.getElementById(videoID).play();
+      });
+
+      await SpecialPowers.pushPrefEnv({
+        set: [[IMPROVED_CONTROLS_ENABLED_PREF, true]],
+      });
+
+      // Open the video in PiP
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      let fullscreenButton = pipWin.document.getElementById("fullscreen");
+      let seekForwardButton = pipWin.document.getElementById("seekForward");
+      let seekBackwardButton = pipWin.document.getElementById("seekBackward");
+
+      // Try seek forward button
+      let seekedForwardPromise = waitForVideoEvent("seeked");
+      EventUtils.synthesizeMouseAtCenter(seekForwardButton, {}, pipWin);
+      ok(await seekedForwardPromise, "The Forward button triggers");
+
+      // Try seek backward button
+      let seekedBackwardPromise = waitForVideoEvent("seeked");
+      EventUtils.synthesizeMouseAtCenter(seekBackwardButton, {}, pipWin);
+      ok(await seekedBackwardPromise, "The Backward button triggers");
+
+      // The Fullsreen button appears when the pref is enabled and the fullscreen hidden property is set to false
+      Assert.ok(!fullscreenButton.hidden, "The Fullscreen button is visible");
+
+      // The seek Forward button appears when the pref is enabled and the seek forward button hidden property is set to false
+      Assert.ok(!seekForwardButton.hidden, "The Forward button is visible");
+
+      // The seek Backward button appears when the pref is enabled and the seek backward button hidden property is set to false
+      Assert.ok(!seekBackwardButton.hidden, "The Backward button is visible");
+
+      // CLose the PIP window
+      let pipClosed = BrowserTestUtils.domWindowClosed(pipWin);
+      let closeButton = pipWin.document.getElementById("close");
+      EventUtils.synthesizeMouseAtCenter(closeButton, {}, pipWin);
+      await pipClosed;
+
+      await SpecialPowers.pushPrefEnv({
+        set: [[IMPROVED_CONTROLS_ENABLED_PREF, false]],
+      });
+
+      // Open the video in PiP
+      pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      fullscreenButton = pipWin.document.getElementById("fullscreen");
+      seekForwardButton = pipWin.document.getElementById("seekForward");
+      seekBackwardButton = pipWin.document.getElementById("seekBackward");
+
+      // The Fullsreen button disappears when the pref is disabled and the fullscreen hidden property is set to true
+      Assert.ok(
+        fullscreenButton.hidden,
+        "The Fullscreen button is not visible"
+      );
+
+      // The seek Forward button disappears when the pref is disabled and the seek forward button hidden property is set to true
+      Assert.ok(seekForwardButton.hidden, "The Forward button is not visible");
+
+      // The seek Backward button disappears when the pref is disabled and the seek backward button hidden property is set to true
+      Assert.ok(
+        seekBackwardButton.hidden,
+        "The Backward button is not visible"
+      );
+    }
+  );
+});
+
+/**
+ * Tests the functionality of Picture-in-picture
+ * video scrubber
+ */
+add_task(async function testVideoScrubber() {
+  let videoID = "long";
+
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE_LONG,
+      gBrowser,
+    },
+    async browser => {
+      await ensureVideosReady(browser);
+
+      await SpecialPowers.pushPrefEnv({
+        set: [[IMPROVED_CONTROLS_ENABLED_PREF, true]],
+      });
+
+      // Open the video in PiP
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      let scrubber = pipWin.document.getElementById("scrubber");
+      scrubber.focus();
+
+      let currentTime = await getVideoCurrentTime(browser, videoID);
+      let expectedVideoTime = 0;
+      const duration = await getVideoDuration(browser, videoID);
+      checkTimeCloseEnough(
+        currentTime,
+        expectedVideoTime,
+        "Video current time is 0"
+      );
+
+      let timestampEl = pipWin.document.getElementById("timestamp");
+      let expectedTimestamp = "0:00 / 0:08";
+
+      // Wait for the timestamp to update
+      await timestampUpdated(timestampEl, expectedTimestamp);
+      let actualTimestamp = timestampEl.textContent;
+      is(actualTimestamp, expectedTimestamp, "Timestamp reads 0:00 / 0:08");
+
+      EventUtils.synthesizeKey("KEY_ArrowRight", {}, pipWin);
+
+      currentTime = await getVideoCurrentTime(browser, videoID);
+      expectedVideoTime = 5;
+      checkTimeCloseEnough(
+        currentTime,
+        expectedVideoTime,
+        "Video current time is 5"
+      );
+
+      expectedTimestamp = "0:05 / 0:08";
+      await timestampUpdated(timestampEl, expectedTimestamp);
+      actualTimestamp = timestampEl.textContent;
+      is(actualTimestamp, expectedTimestamp, "Timestamp reads 0:05 / 0:08");
+
+      EventUtils.synthesizeKey("KEY_ArrowLeft", {}, pipWin);
+
+      currentTime = await getVideoCurrentTime(browser, videoID);
+      expectedVideoTime = 0;
+      checkTimeCloseEnough(
+        currentTime,
+        expectedVideoTime,
+        "Video current time is 0"
+      );
+
+      expectedTimestamp = "0:00 / 0:08";
+      await timestampUpdated(timestampEl, expectedTimestamp);
+      actualTimestamp = timestampEl.textContent;
+      is(actualTimestamp, expectedTimestamp, "Timestamp reads 0:00 / 0:08");
+
+      let rect = scrubber.getBoundingClientRect();
+
+      EventUtils.synthesizeMouse(
+        scrubber,
+        rect.width / 2,
+        rect.height / 2,
+        {},
+        pipWin
+      );
+
+      expectedVideoTime = duration / 2;
+      currentTime = await getVideoCurrentTime(browser, videoID);
+      checkTimeCloseEnough(
+        currentTime,
+        expectedVideoTime,
+        "Video current time is 3.98..."
+      );
+
+      expectedTimestamp = "0:04 / 0:08";
+      await timestampUpdated(timestampEl, expectedTimestamp);
+      actualTimestamp = timestampEl.textContent;
+      is(actualTimestamp, expectedTimestamp, "Timestamp reads 0:04 / 0:08");
+
+      EventUtils.synthesizeMouse(
+        scrubber,
+        rect.width / 2,
+        rect.height / 2,
+        { type: "mousedown" },
+        pipWin
+      );
+
+      EventUtils.synthesizeMouse(
+        scrubber,
+        rect.width,
+        rect.height / 2,
+        { type: "mousemove" },
+        pipWin
+      );
+
+      EventUtils.synthesizeMouse(
+        scrubber,
+        rect.width,
+        rect.height / 2,
+        { type: "mouseup" },
+        pipWin
+      );
+
+      expectedVideoTime = duration;
+      currentTime = await getVideoCurrentTime(browser, videoID);
+      checkTimeCloseEnough(
+        currentTime,
+        expectedVideoTime,
+        "Video current time is 7.96..."
+      );
+
+      await ensureMessageAndClosePiP(browser, videoID, pipWin, false);
+    }
+  );
+});
+
+/**
+ * Tests the behavior of the scrubber and position/duration indicator for a
+ * video with an invalid/non-finite duration.
+ */
+add_task(async function testInvalidDuration() {
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE_WITH_NAN_VIDEO_DURATION,
+      gBrowser,
+    },
+    async browser => {
+      const videoID = "nan-duration";
+
+      // This tests skips calling ensureVideosReady, because canplaythrough
+      // will never fire for the NaN duration video.
+
+      await SpecialPowers.pushPrefEnv({
+        set: [[IMPROVED_CONTROLS_ENABLED_PREF, true]],
+      });
+
+      // Open the video in PiP
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      // Both the scrubber and the duration should be hidden.
+      let timestampEl = pipWin.document.getElementById("timestamp");
+      ok(timestampEl.hidden, "Timestamp in the PIP window should be hidden.");
+
+      let scrubberEl = pipWin.document.getElementById("scrubber");
+      ok(
+        scrubberEl.hidden,
+        "Scrubber control in the PIP window should be hidden"
+      );
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_keyboardClosePIPwithESC.js b/toolkit/components/pictureinpicture/tests/browser_keyboardClosePIPwithESC.js
new file mode 100644
index 0000000000..e8860c80f7
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_keyboardClosePIPwithESC.js
@@ -0,0 +1,71 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * tests that the ESC key would stop the player and close the PiP player floating window
+ */
+add_task(async () => {
+  for (let videoID of ["with-controls", "no-controls"]) {
+    info(`Testing ${videoID} case.`);
+
+    let playVideo = () => {
+      return SpecialPowers.spawn(browser, [videoID], async videoID => {
+        return content.document.getElementById(videoID).play();
+      });
+    };
+
+    let tab = await BrowserTestUtils.openNewForegroundTab(gBrowser, TEST_PAGE);
+    let browser = tab.linkedBrowser;
+
+    await playVideo();
+
+    let pipWin = await triggerPictureInPicture(browser, videoID);
+    ok(pipWin, "The Picture-in-Picture window is not there.");
+    ok(
+      !(await isVideoPaused(browser, videoID)),
+      "The video is paused, but should not."
+    );
+    ok(
+      !pipWin.document.fullscreenElement,
+      "PiP should not yet be in fullscreen."
+    );
+
+    let controls = pipWin.document.getElementById("controls");
+    await promiseFullscreenEntered(pipWin, async () => {
+      EventUtils.sendMouseEvent({ type: "dblclick" }, controls, pipWin);
+    });
+
+    ok(
+      pipWin.document.fullscreenElement == pipWin.document.body,
+      "Double-click should have caused to enter fullscreen."
+    );
+
+    await promiseFullscreenExited(pipWin, async () => {
+      EventUtils.synthesizeKey("KEY_Escape", {}, pipWin);
+    });
+
+    ok(
+      !pipWin.document.fullscreenElement,
+      "ESC should have caused to leave fullscreen."
+    );
+    ok(
+      !(await isVideoPaused(browser, videoID)),
+      "The video is paused, but should not."
+    );
+
+    // Try to close the PiP window via the ESC button, since now it is not in fullscreen anymore.
+    EventUtils.synthesizeKey("KEY_Escape", {}, pipWin);
+
+    // then the PiP should have been closed
+    ok(pipWin.closed, "Picture-in-Picture window is not closed, but should.");
+    // and the video should not be playing anymore
+    ok(
+      await isVideoPaused(browser, videoID),
+      "The video is not paused, but should."
+    );
+
+    await BrowserTestUtils.removeTab(tab);
+  }
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_keyboardFullScreenPIPShortcut.js b/toolkit/components/pictureinpicture/tests/browser_keyboardFullScreenPIPShortcut.js
new file mode 100644
index 0000000000..e7288d83d8
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_keyboardFullScreenPIPShortcut.js
@@ -0,0 +1,41 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests that the F-key would enter and exit full screen mode in PiP for the default locale (en-US).
+ */
+add_task(async () => {
+  let tab = await BrowserTestUtils.openNewForegroundTab(gBrowser, TEST_PAGE);
+  let browser = tab.linkedBrowser;
+  let videoID = "with-controls";
+
+  let pipWin = await triggerPictureInPicture(browser, videoID);
+  ok(pipWin, "The Picture-in-Picture window is there.");
+
+  ok(
+    !pipWin.document.fullscreenElement,
+    "PiP should not yet be in fullscreen."
+  );
+
+  await promiseFullscreenEntered(pipWin, async () => {
+    EventUtils.synthesizeKey("f", {}, pipWin);
+  });
+
+  ok(
+    pipWin.document.fullscreenElement == pipWin.document.body,
+    "F-key should have caused to enter fullscreen."
+  );
+
+  await promiseFullscreenExited(pipWin, async () => {
+    EventUtils.synthesizeKey("f", {}, pipWin);
+  });
+
+  ok(
+    !pipWin.document.fullscreenElement,
+    "F-key should have caused to leave fullscreen."
+  );
+
+  await BrowserTestUtils.removeTab(tab);
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_keyboardShortcut.js b/toolkit/components/pictureinpicture/tests/browser_keyboardShortcut.js
new file mode 100644
index 0000000000..a81d99e18c
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_keyboardShortcut.js
@@ -0,0 +1,134 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { TelemetryTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/TelemetryTestUtils.sys.mjs"
+);
+
+const PIP_SHORTCUT_OPEN_EVENTS = [
+  {
+    category: "pictureinpicture",
+    method: "opened_method",
+    object: "shortcut",
+  },
+];
+
+const PIP_SHORTCUT_CLOSE_EVENTS = [
+  {
+    category: "pictureinpicture",
+    method: "closed_method",
+    object: "shortcut",
+  },
+];
+
+/**
+ * Tests that if the user keys in the keyboard shortcut for
+ * Picture-in-Picture, then the first video on the currently
+ * focused page will be opened in the player window.
+ */
+add_task(async function test_pip_keyboard_shortcut() {
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE,
+      gBrowser,
+    },
+    async browser => {
+      Services.telemetry.clearEvents();
+      await ensureVideosReady(browser);
+
+      // In test-page.html, the "with-controls" video is the first one that
+      // appears in the DOM, so this is what we expect to open via the keyboard
+      // shortcut.
+      const VIDEO_ID = "with-controls";
+
+      let domWindowOpened = BrowserTestUtils.domWindowOpenedAndLoaded(null);
+      let videoReady = SpecialPowers.spawn(
+        browser,
+        [VIDEO_ID],
+        async videoID => {
+          let video = content.document.getElementById(videoID);
+          await ContentTaskUtils.waitForCondition(() => {
+            return video.isCloningElementVisually;
+          }, "Video is being cloned visually.");
+        }
+      );
+
+      if (AppConstants.platform == "macosx") {
+        EventUtils.synthesizeKey("]", {
+          accelKey: true,
+          shiftKey: true,
+          altKey: true,
+        });
+      } else {
+        EventUtils.synthesizeKey("]", { accelKey: true, shiftKey: true });
+      }
+
+      let pipWin = await domWindowOpened;
+      await videoReady;
+
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      await ensureMessageAndClosePiP(browser, VIDEO_ID, pipWin, false);
+
+      let openFilter = {
+        category: "pictureinpicture",
+        method: "opened_method",
+        object: "shortcut",
+      };
+      await waitForTelemeryEvents(
+        openFilter,
+        PIP_SHORTCUT_OPEN_EVENTS.length,
+        "content"
+      );
+      TelemetryTestUtils.assertEvents(PIP_SHORTCUT_OPEN_EVENTS, openFilter, {
+        clear: true,
+        process: "content",
+      });
+
+      // Reopen PiP Window
+      pipWin = await triggerPictureInPicture(browser, VIDEO_ID);
+      await videoReady;
+
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      if (AppConstants.platform == "macosx") {
+        EventUtils.synthesizeKey(
+          "]",
+          {
+            accelKey: true,
+            shiftKey: true,
+            altKey: true,
+          },
+          pipWin
+        );
+      } else {
+        EventUtils.synthesizeKey(
+          "]",
+          { accelKey: true, shiftKey: true },
+          pipWin
+        );
+      }
+
+      await BrowserTestUtils.windowClosed(pipWin);
+
+      ok(pipWin.closed, "Picture-in-Picture window closed.");
+
+      let closeFilter = {
+        category: "pictureinpicture",
+        method: "closed_method",
+        object: "shortcut",
+      };
+      await waitForTelemeryEvents(
+        closeFilter,
+        PIP_SHORTCUT_CLOSE_EVENTS.length,
+        "parent"
+      );
+      TelemetryTestUtils.assertEvents(PIP_SHORTCUT_CLOSE_EVENTS, closeFilter, {
+        clear: true,
+        process: "parent",
+      });
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_keyboardShortcutClosePIP.js b/toolkit/components/pictureinpicture/tests/browser_keyboardShortcutClosePIP.js
new file mode 100644
index 0000000000..a85cdd5a63
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_keyboardShortcutClosePIP.js
@@ -0,0 +1,53 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests that keyboard shortcut ctr + w / cmd + w closing PIP window
+ */
+
+add_task(async function test_pip_close_keyboard_shortcut() {
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE,
+      gBrowser,
+    },
+    async browser => {
+      await ensureVideosReady(browser);
+      const VIDEO_ID = "with-controls";
+
+      let domWindowOpened = BrowserTestUtils.domWindowOpenedAndLoaded(null);
+      let videoReady = SpecialPowers.spawn(
+        browser,
+        [VIDEO_ID],
+        async videoID => {
+          let video = content.document.getElementById(videoID);
+          await ContentTaskUtils.waitForCondition(() => {
+            return video.isCloningElementVisually;
+          }, "Video is being cloned visually.");
+        }
+      );
+
+      if (AppConstants.platform == "macosx") {
+        EventUtils.synthesizeKey("]", {
+          accelKey: true,
+          shiftKey: true,
+          altKey: true,
+        });
+      } else {
+        EventUtils.synthesizeKey("]", { accelKey: true, shiftKey: true });
+      }
+
+      let pipWin = await domWindowOpened;
+      await videoReady;
+
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      EventUtils.synthesizeKey("w", { accelKey: true }, pipWin);
+      await BrowserTestUtils.windowClosed(pipWin);
+      ok(await isVideoPaused(browser, VIDEO_ID), "The video is paused");
+      ok(pipWin.closed, "Closed PIP");
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_keyboardShortcutWithNanDuration.js b/toolkit/components/pictureinpicture/tests/browser_keyboardShortcutWithNanDuration.js
new file mode 100644
index 0000000000..c812dc3e4e
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_keyboardShortcutWithNanDuration.js
@@ -0,0 +1,54 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+add_task(async function test_pip_keyboard_shortcut_with_nan_video_duration() {
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE_WITH_NAN_VIDEO_DURATION,
+      gBrowser,
+    },
+    async browser => {
+      const VIDEO_ID = "test-video";
+
+      await SpecialPowers.spawn(browser, [VIDEO_ID], async videoID => {
+        let video = content.document.getElementById(videoID);
+        if (video.readyState < content.HTMLMediaElement.HAVE_ENOUGH_DATA) {
+          info(`Waiting for 'canplaythrough' for ${videoID}`);
+          await ContentTaskUtils.waitForEvent(video, "canplaythrough");
+        }
+      });
+
+      let domWindowOpened = BrowserTestUtils.domWindowOpenedAndLoaded(null);
+
+      let videoReady = SpecialPowers.spawn(
+        browser,
+        [VIDEO_ID],
+        async videoID => {
+          let video = content.document.getElementById(videoID);
+          await ContentTaskUtils.waitForCondition(() => {
+            return video.isCloningElementVisually;
+          }, "Video is being cloned visually.");
+        }
+      );
+
+      if (AppConstants.platform == "macosx") {
+        EventUtils.synthesizeKey("]", {
+          accelKey: true,
+          shiftKey: true,
+          altKey: true,
+        });
+      } else {
+        EventUtils.synthesizeKey("]", { accelKey: true, shiftKey: true });
+      }
+
+      let pipWin = await domWindowOpened;
+      await videoReady;
+
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      pipWin.close();
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_keyboardToggle.js b/toolkit/components/pictureinpicture/tests/browser_keyboardToggle.js
new file mode 100644
index 0000000000..a70100de85
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_keyboardToggle.js
@@ -0,0 +1,32 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests to ensure that tabbing to the pip button and pressing space works
+ * to open the picture-in-picture window.
+ */
+add_task(async () => {
+  let videoID = "with-controls";
+
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE,
+      gBrowser,
+    },
+    async browser => {
+      await ensureVideosReady(browser);
+
+      // Open the video in PiP
+      let pipWin = await triggerPictureInPicture(browser, videoID, () => {
+        EventUtils.synthesizeKey("KEY_Tab", {}); // play button
+        EventUtils.synthesizeKey("KEY_Tab", {}); // pip button
+        EventUtils.synthesizeKey(" ", {});
+      });
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      await BrowserTestUtils.closeWindow(pipWin);
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_mediaStreamVideos.js b/toolkit/components/pictureinpicture/tests/browser_mediaStreamVideos.js
new file mode 100644
index 0000000000..46b36a3a6e
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_mediaStreamVideos.js
@@ -0,0 +1,59 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * This test checks that the media stream video format has functional
+ * support for PiP
+ */
+add_task(async function test_mediaStreamVideos() {
+  await testToggle(
+    TEST_ROOT + "test-media-stream.html",
+    {
+      "with-controls": { canToggle: true },
+      "no-controls": { canToggle: true },
+    },
+    async browser => {
+      await SpecialPowers.spawn(browser, [], async () => {
+        // Construct a new video element, and capture a stream from it
+        // to redirect to both testing videos. Create the captureStreams after
+        // we have metadata so tracks are immediately available, but wait with
+        // playback until the setup is done.
+
+        function logEvent(element, ev) {
+          element.addEventListener(ev, () =>
+            info(
+              `${element.id} got event ${ev}. currentTime=${element.currentTime}`
+            )
+          );
+        }
+
+        const newVideo = content.document.createElement("video");
+        newVideo.id = "new-video";
+        newVideo.src = "test-video.mp4";
+        newVideo.preload = "auto";
+        logEvent(newVideo, "timeupdate");
+        logEvent(newVideo, "ended");
+        content.document.body.appendChild(newVideo);
+        await ContentTaskUtils.waitForEvent(newVideo, "loadedmetadata");
+
+        const mediastreamPlayingPromises = [];
+        for (let videoID of ["with-controls", "no-controls"]) {
+          const testedVideo = content.document.createElement("video");
+          testedVideo.id = videoID;
+          testedVideo.srcObject = newVideo.mozCaptureStream();
+          testedVideo.play();
+          mediastreamPlayingPromises.push(
+            new Promise(r => (testedVideo.onplaying = r))
+          );
+          content.document.body.prepend(testedVideo);
+        }
+
+        await newVideo.play();
+        await Promise.all(mediastreamPlayingPromises);
+        newVideo.pause();
+      });
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_mouseButtonVariation.js b/toolkit/components/pictureinpicture/tests/browser_mouseButtonVariation.js
new file mode 100644
index 0000000000..f424093215
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_mouseButtonVariation.js
@@ -0,0 +1,97 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests that if the user mousedown's on a Picture-in-Picture toggle,
+ * but then mouseup's on something completely different, that we still
+ * open a Picture-in-Picture window, and that the mouse button events are
+ * all suppressed. Also ensures that a subsequent click on the document
+ * body results in all mouse button events firing normally.
+ */
+add_task(async () => {
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: TEST_PAGE,
+    },
+    async browser => {
+      await SimpleTest.promiseFocus(browser);
+      await ensureVideosReady(browser);
+      let videoID = "no-controls";
+
+      await prepareForToggleClick(browser, videoID);
+
+      // Hover the mouse over the video to reveal the toggle, which is necessary
+      // if we want to click on the toggle.
+      await BrowserTestUtils.synthesizeMouseAtCenter(
+        `#${videoID}`,
+        {
+          type: "mousemove",
+        },
+        browser
+      );
+      await BrowserTestUtils.synthesizeMouseAtCenter(
+        `#${videoID}`,
+        {
+          type: "mouseover",
+        },
+        browser
+      );
+
+      info("Waiting for toggle to become visible");
+      await toggleOpacityReachesThreshold(browser, videoID, "hoverVideo");
+
+      let toggleClientRect = await getToggleClientRect(browser, videoID);
+
+      // The toggle center, because of how it slides out, is actually outside
+      // of the bounds of a click event. For now, we move the mouse in by a
+      // hard-coded 15 pixels along the x and y axis to achieve the hover.
+      let toggleLeft = toggleClientRect.left + 15;
+      let toggleTop = toggleClientRect.top + 15;
+
+      info(
+        "Clicking on toggle, and expecting a Picture-in-Picture window to open"
+      );
+      // We need to wait for the window to have completed loading before we
+      // can close it as the document's type required by closeWindow may not
+      // be available.
+      let domWindowOpened = BrowserTestUtils.domWindowOpenedAndLoaded(null);
+
+      await BrowserTestUtils.synthesizeMouseAtPoint(
+        toggleLeft,
+        toggleTop,
+        {
+          type: "mousedown",
+        },
+        browser
+      );
+
+      await BrowserTestUtils.synthesizeMouseAtPoint(
+        1,
+        1,
+        {
+          type: "mouseup",
+        },
+        browser
+      );
+
+      let win = await domWindowOpened;
+      ok(win, "A Picture-in-Picture window opened.");
+
+      await SpecialPowers.spawn(browser, [videoID], async videoID => {
+        let video = content.document.getElementById(videoID);
+        await ContentTaskUtils.waitForCondition(() => {
+          return video.isCloningElementVisually;
+        }, "Video is being cloned visually.");
+      });
+
+      await BrowserTestUtils.closeWindow(win);
+      await assertSawMouseEvents(browser, false);
+
+      await BrowserTestUtils.synthesizeMouseAtPoint(1, 1, {}, browser);
+      await assertSawMouseEvents(browser, true);
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_multiPip.js b/toolkit/components/pictureinpicture/tests/browser_multiPip.js
new file mode 100644
index 0000000000..2821c0d484
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_multiPip.js
@@ -0,0 +1,225 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+async function createTab() {
+  return BrowserTestUtils.openNewForegroundTab({
+    gBrowser,
+    opening: TEST_PAGE,
+    waitForLoad: true,
+  });
+}
+
+function getTelemetryMaxPipCount(resetMax = false) {
+  const scalarData = Services.telemetry.getSnapshotForScalars(
+    "main",
+    resetMax
+  ).parent;
+  return scalarData["pictureinpicture.most_concurrent_players"];
+}
+
+/**
+ * Tests that multiple PiPs can be opened and closed in a single tab
+ */
+add_task(async () => {
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE,
+      gBrowser,
+    },
+    async browser => {
+      let firstPip = await triggerPictureInPicture(browser, "with-controls");
+      ok(firstPip, "Got first PiP window");
+
+      let secondPip = await triggerPictureInPicture(browser, "no-controls");
+      ok(secondPip, "Got second PiP window");
+
+      await ensureMessageAndClosePiP(browser, "with-controls", firstPip, false);
+      info("First PiP was still open and is now closed");
+
+      await ensureMessageAndClosePiP(browser, "no-controls", secondPip, false);
+      info("Second PiP was still open and is now closed");
+    }
+  );
+});
+
+/**
+ * Tests that multiple PiPs can be opened and closed across different tabs
+ */
+add_task(async () => {
+  let firstTab = await createTab();
+  let secondTab = await createTab();
+
+  gBrowser.selectedTab = firstTab;
+
+  let firstPip = await triggerPictureInPicture(
+    firstTab.linkedBrowser,
+    "with-controls"
+  );
+  ok(firstPip, "Got first PiP window");
+
+  gBrowser.selectedTab = secondTab;
+
+  let secondPip = await triggerPictureInPicture(
+    secondTab.linkedBrowser,
+    "with-controls"
+  );
+  ok(secondPip, "Got second PiP window");
+
+  await ensureMessageAndClosePiP(
+    firstTab.linkedBrowser,
+    "with-controls",
+    firstPip,
+    false
+  );
+  info("First Picture-in-Picture window was open and is now closed.");
+
+  await ensureMessageAndClosePiP(
+    secondTab.linkedBrowser,
+    "with-controls",
+    secondPip,
+    false
+  );
+  info("Second Picture-in-Picture window was open and is now closed.");
+
+  BrowserTestUtils.removeTab(firstTab);
+  BrowserTestUtils.removeTab(secondTab);
+});
+
+/**
+ * Tests that when a tab is closed; that only PiPs originating from this tab
+ * are closed as well
+ */
+add_task(async () => {
+  let firstTab = await createTab();
+  let secondTab = await createTab();
+
+  let firstPip = await triggerPictureInPicture(
+    firstTab.linkedBrowser,
+    "with-controls"
+  );
+  ok(firstPip, "Got first PiP window");
+
+  let secondPip = await triggerPictureInPicture(
+    secondTab.linkedBrowser,
+    "with-controls"
+  );
+  ok(secondPip, "Got second PiP window");
+
+  let firstClosed = BrowserTestUtils.domWindowClosed(firstPip);
+  BrowserTestUtils.removeTab(firstTab);
+  await firstClosed;
+  info("First PiP closed after closing the first tab");
+
+  await assertVideoIsBeingCloned(secondTab.linkedBrowser, "#with-controls");
+  info("Second PiP is still open after first tab close");
+
+  let secondClosed = BrowserTestUtils.domWindowClosed(secondPip);
+  BrowserTestUtils.removeTab(secondTab);
+  await secondClosed;
+  info("Second PiP closed after closing the second tab");
+});
+
+/**
+ * Check that correct number of pip players are recorded for Telemetry
+ * tracking
+ */
+add_task(async () => {
+  // run this to flush recorded values from previous tests
+  getTelemetryMaxPipCount(true);
+
+  let firstTab = await createTab();
+  let secondTab = await createTab();
+
+  gBrowser.selectedTab = firstTab;
+
+  let firstPip = await triggerPictureInPicture(
+    firstTab.linkedBrowser,
+    "with-controls"
+  );
+  ok(firstPip, "Got first PiP window");
+
+  Assert.equal(
+    getTelemetryMaxPipCount(true),
+    1,
+    "There should only be 1 PiP window"
+  );
+
+  let secondPip = await triggerPictureInPicture(
+    firstTab.linkedBrowser,
+    "no-controls"
+  );
+  ok(secondPip, "Got second PiP window");
+
+  Assert.equal(
+    getTelemetryMaxPipCount(true),
+    2,
+    "There should be 2 PiP windows"
+  );
+
+  await ensureMessageAndClosePiP(
+    firstTab.linkedBrowser,
+    "no-controls",
+    secondPip,
+    false
+  );
+  info("Second PiP was open and is now closed");
+
+  gBrowser.selectedTab = secondTab;
+
+  let thirdPip = await triggerPictureInPicture(
+    secondTab.linkedBrowser,
+    "with-controls"
+  );
+  ok(thirdPip, "Got third PiP window");
+
+  let fourthPip = await triggerPictureInPicture(
+    secondTab.linkedBrowser,
+    "no-controls"
+  );
+  ok(fourthPip, "Got fourth PiP window");
+
+  Assert.equal(
+    getTelemetryMaxPipCount(false),
+    3,
+    "There should now be 3 PiP windows"
+  );
+
+  gBrowser.selectedTab = firstTab;
+
+  await ensureMessageAndClosePiP(
+    firstTab.linkedBrowser,
+    "with-controls",
+    firstPip,
+    false
+  );
+  info("First PiP was open, it is now closed.");
+
+  gBrowser.selectedTab = secondTab;
+
+  await ensureMessageAndClosePiP(
+    secondTab.linkedBrowser,
+    "with-controls",
+    thirdPip,
+    false
+  );
+  info("Third PiP was open, it is now closed.");
+
+  await ensureMessageAndClosePiP(
+    secondTab.linkedBrowser,
+    "no-controls",
+    fourthPip,
+    false
+  );
+  info("Fourth PiP was open, it is now closed.");
+
+  Assert.equal(
+    getTelemetryMaxPipCount(false),
+    3,
+    "Max PiP count should still be 3"
+  );
+
+  BrowserTestUtils.removeTab(firstTab);
+  BrowserTestUtils.removeTab(secondTab);
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_nimbusDisplayDuration.js b/toolkit/components/pictureinpicture/tests/browser_nimbusDisplayDuration.js
new file mode 100644
index 0000000000..a2e7e66b40
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_nimbusDisplayDuration.js
@@ -0,0 +1,214 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { ExperimentFakes } = ChromeUtils.importESModule(
+  "resource://testing-common/NimbusTestUtils.sys.mjs"
+);
+
+const TOGGLE_HAS_USED_PREF =
+  "media.videocontrols.picture-in-picture.video-toggle.has-used";
+const TOGGLE_FIRST_SEEN_PREF =
+  "media.videocontrols.picture-in-picture.video-toggle.first-seen-secs";
+
+/**
+ * This tests that the first-time toggle doesn't change to the icon toggle.
+ */
+add_task(async function test_experiment_control_displayDuration() {
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: TEST_PAGE,
+    },
+    async browser => {
+      await SimpleTest.promiseFocus(browser);
+      await ensureVideosReady(browser);
+
+      await SpecialPowers.pushPrefEnv({
+        set: [
+          [TOGGLE_FIRST_SEEN_PREF, 0],
+          [TOGGLE_HAS_USED_PREF, false],
+        ],
+      });
+
+      let videoID = "with-controls";
+      await hoverToggle(browser, videoID);
+
+      const hasUsed = Services.prefs.getBoolPref(TOGGLE_HAS_USED_PREF);
+      const firstSeen = Services.prefs.getIntPref(TOGGLE_FIRST_SEEN_PREF);
+
+      Assert.ok(!hasUsed, "has-used is false and toggle is not icon");
+      Assert.notEqual(firstSeen, 0, "First seen should not be 0");
+    }
+  );
+});
+
+/**
+ * This tests that the first-time toggle changes to the icon toggle
+ * if the displayDuration end date is reached or passed.
+ */
+add_task(async function test_experiment_displayDuration_end_date_was_reached() {
+  let doExperimentCleanup = await ExperimentFakes.enrollWithFeatureConfig({
+    featureId: "pictureinpicture",
+    value: {
+      displayDuration: 1,
+    },
+  });
+
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: TEST_PAGE,
+    },
+    async browser => {
+      await SimpleTest.promiseFocus(browser);
+      await ensureVideosReady(browser);
+
+      await SpecialPowers.pushPrefEnv({
+        set: [
+          [TOGGLE_FIRST_SEEN_PREF, 222],
+          [TOGGLE_HAS_USED_PREF, false],
+        ],
+      });
+
+      let videoID = "with-controls";
+      await hoverToggle(browser, videoID);
+
+      const hasUsed = Services.prefs.getBoolPref(TOGGLE_HAS_USED_PREF);
+      const firstSeen = Services.prefs.getIntPref(TOGGLE_FIRST_SEEN_PREF);
+
+      Assert.ok(hasUsed, "has-used is true and toggle is icon");
+      Assert.equal(firstSeen, 222, "First seen should remain unchanged");
+    }
+  );
+
+  await doExperimentCleanup();
+});
+
+/**
+ * This tests that the first-time toggle does not change to the icon toggle
+ * if the displayDuration end date is not yet reached or passed.
+ */
+add_task(async function test_experiment_displayDuration_end_date_not_reached() {
+  let doExperimentCleanup = await ExperimentFakes.enrollWithFeatureConfig({
+    featureId: "pictureinpicture",
+    value: {
+      displayDuration: 5,
+    },
+  });
+
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: TEST_PAGE,
+    },
+    async browser => {
+      await SimpleTest.promiseFocus(browser);
+      await ensureVideosReady(browser);
+
+      const currentDateSec = Math.round(Date.now() / 1000);
+
+      await SpecialPowers.pushPrefEnv({
+        set: [
+          [TOGGLE_FIRST_SEEN_PREF, currentDateSec],
+          [TOGGLE_HAS_USED_PREF, false],
+        ],
+      });
+
+      let videoID = "with-controls";
+      await hoverToggle(browser, videoID);
+
+      const hasUsed = Services.prefs.getBoolPref(TOGGLE_HAS_USED_PREF);
+      const firstSeen = Services.prefs.getIntPref(TOGGLE_FIRST_SEEN_PREF);
+
+      Assert.ok(!hasUsed, "has-used is false and toggle is not icon");
+      Assert.equal(
+        firstSeen,
+        currentDateSec,
+        "First seen should remain unchanged"
+      );
+    }
+  );
+
+  await doExperimentCleanup();
+});
+
+/**
+ * This tests that the toggle does not change to the icon toggle if duration is negative.
+ */
+add_task(async function test_experiment_displayDuration_negative_duration() {
+  let doExperimentCleanup = await ExperimentFakes.enrollWithFeatureConfig({
+    featureId: "pictureinpicture",
+    value: {
+      displayDuration: -1,
+    },
+  });
+
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: TEST_PAGE,
+    },
+    async browser => {
+      await SimpleTest.promiseFocus(browser);
+      await ensureVideosReady(browser);
+
+      await SpecialPowers.pushPrefEnv({
+        set: [
+          [TOGGLE_FIRST_SEEN_PREF, 0],
+          [TOGGLE_HAS_USED_PREF, false],
+        ],
+      });
+
+      let videoID = "with-controls";
+      await hoverToggle(browser, videoID);
+
+      const hasUsed = Services.prefs.getBoolPref(TOGGLE_HAS_USED_PREF);
+      const firstSeen = Services.prefs.getIntPref(TOGGLE_FIRST_SEEN_PREF);
+
+      Assert.ok(!hasUsed, "has-used is false and toggle is not icon");
+      Assert.notEqual(firstSeen, 0, "First seen should not be 0");
+    }
+  );
+
+  await doExperimentCleanup();
+});
+
+/**
+ * This tests that first-seen is only recorded for the first-time toggle.
+ */
+add_task(async function test_experiment_displayDuration_already_icon() {
+  let doExperimentCleanup = await ExperimentFakes.enrollWithFeatureConfig({
+    featureId: "pictureinpicture",
+    value: {
+      displayDuration: 1,
+    },
+  });
+
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: TEST_PAGE,
+    },
+    async browser => {
+      await SimpleTest.promiseFocus(browser);
+      await ensureVideosReady(browser);
+
+      await SpecialPowers.pushPrefEnv({
+        set: [
+          [TOGGLE_FIRST_SEEN_PREF, 0],
+          [TOGGLE_HAS_USED_PREF, true],
+        ],
+      });
+
+      let videoID = "with-controls";
+      await hoverToggle(browser, videoID);
+
+      const firstSeen = Services.prefs.getIntPref(TOGGLE_FIRST_SEEN_PREF);
+      Assert.equal(firstSeen, 0, "First seen should be 0");
+    }
+  );
+
+  await doExperimentCleanup();
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_nimbusFirstTimeStyleVariant.js b/toolkit/components/pictureinpicture/tests/browser_nimbusFirstTimeStyleVariant.js
new file mode 100644
index 0000000000..7002767b74
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_nimbusFirstTimeStyleVariant.js
@@ -0,0 +1,118 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { ExperimentFakes } = ChromeUtils.importESModule(
+  "resource://testing-common/NimbusTestUtils.sys.mjs"
+);
+
+const EXPERIMENT_CLASS_NAME = "experiment";
+
+/**
+ * This tests that the original PiP toggle design is shown.
+ */
+add_task(async function test_experiment_control_toggle_style() {
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: TEST_PAGE,
+    },
+    async browser => {
+      await SimpleTest.promiseFocus(browser);
+      await ensureVideosReady(browser);
+
+      const PIP_PREF =
+        "media.videocontrols.picture-in-picture.video-toggle.has-used";
+      await SpecialPowers.pushPrefEnv({
+        set: [[PIP_PREF, false]],
+      });
+
+      let videoID = "with-controls";
+      await hoverToggle(browser, videoID);
+
+      await SpecialPowers.spawn(
+        browser,
+        [EXPERIMENT_CLASS_NAME],
+        async EXPERIMENT_CLASS_NAME => {
+          let video = content.document.getElementById("with-controls");
+          let shadowRoot = video.openOrClosedShadowRoot;
+
+          let controlsContainer =
+            shadowRoot.querySelector(".controlsContainer");
+          let pipWrapper = shadowRoot.querySelector(".pip-wrapper");
+          let pipExplainer = shadowRoot.querySelector(".pip-explainer");
+
+          Assert.ok(
+            !controlsContainer.classList.contains(EXPERIMENT_CLASS_NAME)
+          );
+          Assert.ok(!pipWrapper.classList.contains(EXPERIMENT_CLASS_NAME));
+          Assert.ok(
+            ContentTaskUtils.is_visible(pipExplainer),
+            "The PiP message should be visible on the toggle"
+          );
+        }
+      );
+    }
+  );
+});
+
+/**
+ * This tests that the variant PiP toggle design is shown if Nimbus
+ * variable `oldToggle` is false.
+ */
+add_task(async function test_experiment_toggle_style() {
+  let doExperimentCleanup = await ExperimentFakes.enrollWithFeatureConfig({
+    featureId: "pictureinpicture",
+    value: {
+      oldToggle: false,
+    },
+  });
+
+  registerCleanupFunction(async function () {
+    await doExperimentCleanup();
+  });
+
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: TEST_PAGE,
+    },
+    async browser => {
+      await SimpleTest.promiseFocus(browser);
+      await ensureVideosReady(browser);
+
+      const PIP_PREF =
+        "media.videocontrols.picture-in-picture.video-toggle.has-used";
+      await SpecialPowers.pushPrefEnv({
+        set: [[PIP_PREF, false]],
+      });
+
+      let videoID = "with-controls";
+      await hoverToggle(browser, videoID);
+
+      await SpecialPowers.spawn(
+        browser,
+        [EXPERIMENT_CLASS_NAME],
+        async EXPERIMENT_CLASS_NAME => {
+          let video = content.document.getElementById("with-controls");
+          let shadowRoot = video.openOrClosedShadowRoot;
+
+          let controlsContainer =
+            shadowRoot.querySelector(".controlsContainer");
+          let pipWrapper = shadowRoot.querySelector(".pip-wrapper");
+          let pipExplainer = shadowRoot.querySelector(".pip-explainer");
+
+          Assert.ok(
+            controlsContainer.classList.contains(EXPERIMENT_CLASS_NAME)
+          );
+          Assert.ok(pipWrapper.classList.contains(EXPERIMENT_CLASS_NAME));
+          Assert.ok(
+            ContentTaskUtils.is_hidden(pipExplainer),
+            "The PiP message should not be visible on the toggle"
+          );
+        }
+      );
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_nimbusMessageFirstTimePip.js b/toolkit/components/pictureinpicture/tests/browser_nimbusMessageFirstTimePip.js
new file mode 100644
index 0000000000..e998b4f65d
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_nimbusMessageFirstTimePip.js
@@ -0,0 +1,121 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { ExperimentFakes } = ChromeUtils.importESModule(
+  "resource://testing-common/NimbusTestUtils.sys.mjs"
+);
+
+const PIP_EXPERIMENT_MESSAGE = "Hello world message";
+const PIP_EXPERIMENT_TITLE = "Hello world title";
+
+/**
+ * This tests that the original DTD string is shown for the PiP toggle
+ */
+add_task(async function test_experiment_control() {
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: TEST_PAGE,
+    },
+    async browser => {
+      const l10n = new Localization(
+        ["branding/brand.ftl", "toolkit/global/videocontrols.ftl"],
+        true
+      );
+
+      let pipExplainerMessage = l10n.formatValueSync(
+        "videocontrols-picture-in-picture-explainer3"
+      );
+
+      await SimpleTest.promiseFocus(browser);
+      await ensureVideosReady(browser);
+
+      const PIP_PREF =
+        "media.videocontrols.picture-in-picture.video-toggle.has-used";
+      await SpecialPowers.pushPrefEnv({
+        set: [[PIP_PREF, false]],
+      });
+
+      let videoID = "with-controls";
+      await hoverToggle(browser, videoID);
+
+      await SpecialPowers.spawn(
+        browser,
+        [pipExplainerMessage],
+        async function (pipExplainerMessage) {
+          let video = content.document.getElementById("with-controls");
+          let shadowRoot = video.openOrClosedShadowRoot;
+          let pipButton = shadowRoot.querySelector(".pip-explainer");
+
+          Assert.equal(
+            pipButton.textContent.trim(),
+            pipExplainerMessage,
+            "The PiP explainer is default"
+          );
+        }
+      );
+    }
+  );
+});
+
+/**
+ * This tests that the experiment message is shown for the PiP toggle
+ */
+add_task(async function test_experiment_message() {
+  let doExperimentCleanup = await ExperimentFakes.enrollWithFeatureConfig({
+    featureId: "pictureinpicture",
+    value: {
+      title: PIP_EXPERIMENT_TITLE,
+      message: PIP_EXPERIMENT_MESSAGE,
+    },
+  });
+
+  registerCleanupFunction(async function () {
+    await doExperimentCleanup();
+  });
+
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: TEST_PAGE,
+    },
+    async browser => {
+      await SimpleTest.promiseFocus(browser);
+      await ensureVideosReady(browser);
+
+      const PIP_PREF =
+        "media.videocontrols.picture-in-picture.video-toggle.has-used";
+      await SpecialPowers.pushPrefEnv({
+        set: [[PIP_PREF, false]],
+      });
+
+      let videoID = "with-controls";
+      await hoverToggle(browser, videoID);
+
+      await SpecialPowers.spawn(
+        browser,
+        [PIP_EXPERIMENT_MESSAGE, PIP_EXPERIMENT_TITLE],
+        async function (PIP_EXPERIMENT_MESSAGE, PIP_EXPERIMENT_TITLE) {
+          let video = content.document.getElementById("with-controls");
+          let shadowRoot = video.openOrClosedShadowRoot;
+          let pipExplainer = shadowRoot.querySelector(".pip-explainer");
+          let pipLabel = shadowRoot.querySelector(".pip-label");
+
+          Assert.equal(
+            pipExplainer.textContent.trim(),
+            PIP_EXPERIMENT_MESSAGE,
+            "The PiP explainer is being overridden by the experiment"
+          );
+
+          Assert.equal(
+            pipLabel.textContent.trim(),
+            PIP_EXPERIMENT_TITLE,
+            "The PiP label is being overridden by the experiment"
+          );
+        }
+      );
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_nimbusShowIconOnly.js b/toolkit/components/pictureinpicture/tests/browser_nimbusShowIconOnly.js
new file mode 100644
index 0000000000..e7d6fc2328
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_nimbusShowIconOnly.js
@@ -0,0 +1,114 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { ExperimentFakes } = ChromeUtils.importESModule(
+  "resource://testing-common/NimbusTestUtils.sys.mjs"
+);
+
+const PIP_EXPERIMENT_MESSAGE = "Hello world message";
+const PIP_EXPERIMENT_TITLE = "Hello world title";
+
+/**
+ * This tests that the original DTD string is shown for the PiP toggle
+ */
+add_task(async function test_experiment_control() {
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: TEST_PAGE,
+    },
+    async browser => {
+      const l10n = new Localization(
+        ["branding/brand.ftl", "toolkit/global/videocontrols.ftl"],
+        true
+      );
+
+      let pipExplainerMessage = l10n.formatValueSync(
+        "videocontrols-picture-in-picture-explainer3"
+      );
+
+      await SimpleTest.promiseFocus(browser);
+      await ensureVideosReady(browser);
+
+      const PIP_PREF =
+        "media.videocontrols.picture-in-picture.video-toggle.has-used";
+      await SpecialPowers.pushPrefEnv({
+        set: [[PIP_PREF, false]],
+      });
+
+      let videoID = "with-controls";
+      await hoverToggle(browser, videoID);
+
+      await SpecialPowers.spawn(
+        browser,
+        [pipExplainerMessage],
+        async function (pipExplainerMessage) {
+          let video = content.document.getElementById("with-controls");
+          let shadowRoot = video.openOrClosedShadowRoot;
+          let pipButton = shadowRoot.querySelector(".pip-explainer");
+
+          Assert.equal(
+            pipButton.textContent.trim(),
+            pipExplainerMessage,
+            "The PiP explainer is default"
+          );
+        }
+      );
+    }
+  );
+});
+
+/**
+ * This tests that the experiment is showing the icon only
+ */
+add_task(async function test_experiment_iconOnly() {
+  let experimentCleanup = await ExperimentFakes.enrollWithFeatureConfig({
+    featureId: "pictureinpicture",
+    value: {
+      showIconOnly: true,
+    },
+  });
+
+  registerCleanupFunction(async function () {
+    await experimentCleanup();
+  });
+
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: TEST_PAGE,
+    },
+    async browser => {
+      await SimpleTest.promiseFocus(browser);
+      await ensureVideosReady(browser);
+
+      const PIP_PREF =
+        "media.videocontrols.picture-in-picture.video-toggle.has-used";
+      await SpecialPowers.pushPrefEnv({
+        set: [[PIP_PREF, false]],
+      });
+
+      let videoID = "with-controls";
+      await hoverToggle(browser, videoID);
+
+      await SpecialPowers.spawn(browser, [], async function () {
+        let video = content.document.getElementById("with-controls");
+        let shadowRoot = video.openOrClosedShadowRoot;
+        let pipExpanded = shadowRoot.querySelector(".pip-expanded");
+        let pipIcon = shadowRoot.querySelector("div.pip-icon");
+
+        Assert.ok(
+          ContentTaskUtils.is_hidden(pipExpanded),
+          "The PiP explainer hidden by the experiment"
+        );
+
+        Assert.ok(
+          ContentTaskUtils.is_visible(pipIcon),
+          "The PiP icon is visible by the experiment"
+        );
+      });
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_noPlayerControlsOnMiddleRightClick.js b/toolkit/components/pictureinpicture/tests/browser_noPlayerControlsOnMiddleRightClick.js
new file mode 100644
index 0000000000..e021900cad
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_noPlayerControlsOnMiddleRightClick.js
@@ -0,0 +1,53 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests that no player controls are triggered by middle or
+ * right click.
+ */
+add_task(async () => {
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      ["media.videocontrols.picture-in-picture.audio-toggle.enabled", true],
+    ],
+  });
+  let videoID = "with-controls";
+  info(`Testing ${videoID} case.`);
+
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE,
+      gBrowser,
+    },
+    async browser => {
+      await ensureVideosReady(browser);
+      await SpecialPowers.spawn(browser, [videoID], async videoID => {
+        await content.document.getElementById(videoID).play();
+      });
+
+      // Open the video in PiP
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+
+      let playPause = pipWin.document.getElementById("playpause");
+      let audioButton = pipWin.document.getElementById("audio");
+
+      // Middle click the pause button
+      EventUtils.synthesizeMouseAtCenter(playPause, { button: 1 }, pipWin);
+      ok(!(await isVideoPaused(browser, videoID)), "The video is not paused.");
+
+      // Right click the pause button
+      EventUtils.synthesizeMouseAtCenter(playPause, { button: 2 }, pipWin);
+      ok(!(await isVideoPaused(browser, videoID)), "The video is not paused.");
+
+      // Middle click the mute button
+      EventUtils.synthesizeMouseAtCenter(audioButton, { button: 1 }, pipWin);
+      ok(!(await isVideoMuted(browser, videoID)), "The audio is not muted.");
+
+      // Right click the mute button
+      EventUtils.synthesizeMouseAtCenter(audioButton, { button: 2 }, pipWin);
+      ok(!(await isVideoMuted(browser, videoID)), "The audio is not muted.");
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_noToggleOnAudio.js b/toolkit/components/pictureinpicture/tests/browser_noToggleOnAudio.js
new file mode 100644
index 0000000000..b6d434cf8c
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_noToggleOnAudio.js
@@ -0,0 +1,46 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests that if a <video> element only has audio, and no video
+ * frames, that we do not show the toggle.
+ */
+add_task(async function test_no_toggle_on_audio() {
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: TEST_ROOT + "owl.mp3",
+    },
+    async browser => {
+      await ensureVideosReady(browser);
+      await SimpleTest.promiseFocus(browser);
+
+      // The media player document we create for owl.mp3 inserts a <video>
+      // element pointed at the .mp3 file, which is what we're trying to
+      // test for. The <video> element does not get an ID created for it
+      // though, so we sneak one in with SpecialPowers.spawn so that we
+      // can use testToggleHelper (which requires an ID).
+      //
+      // testToggleHelper also wants click-event-helper.js loaded in the
+      // document, so we insert that too.
+      const VIDEO_ID = "video-element";
+      const SCRIPT_SRC = "click-event-helper.js";
+      await SpecialPowers.spawn(
+        browser,
+        [VIDEO_ID, SCRIPT_SRC],
+        async function (videoID, scriptSrc) {
+          let video = content.document.querySelector("video");
+          video.id = videoID;
+
+          let script = content.document.createElement("script");
+          script.src = scriptSrc;
+          content.document.head.appendChild(script);
+        }
+      );
+
+      await testToggleHelper(browser, VIDEO_ID, false);
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_occluded_window.js b/toolkit/components/pictureinpicture/tests/browser_occluded_window.js
new file mode 100644
index 0000000000..6ee66f2ade
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_occluded_window.js
@@ -0,0 +1,258 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests that the forceAppWindowActive flag is correctly set whenever a PiP window is opened
+ * and closed across multiple tabs on the same browser window.
+ */
+add_task(async function forceActiveMultiPiPTabs() {
+  let videoID = "with-controls";
+
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE,
+      gBrowser,
+    },
+    async browser => {
+      await ensureVideosReady(browser);
+
+      let bc = browser.ownerGlobal.browsingContext;
+      info("is window active: " + bc.isActive);
+
+      info("Opening new tab");
+      let newTab = await BrowserTestUtils.openNewForegroundTab(
+        gBrowser,
+        TEST_PAGE
+      );
+      let newTabBrowser = newTab.linkedBrowser;
+      await ensureVideosReady(newTabBrowser);
+
+      ok(!bc.forceAppWindowActive, "Forced window active should be false");
+      info("is window active: " + bc.isActive);
+
+      info("Now opening PiP windows");
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      ok(
+        bc.forceAppWindowActive,
+        "Forced window active should be true since PiP is open"
+      );
+      info("is window active: " + bc.isActive);
+
+      let newTabPiPWin = await triggerPictureInPicture(newTabBrowser, videoID);
+      ok(newTabPiPWin, "Got Picture-in-Picture window in new tab");
+      ok(
+        bc.forceAppWindowActive,
+        "Force window active should still be true after opening a new PiP window in new tab"
+      );
+      info("is window active: " + bc.isActive);
+
+      let pipClosedNewTab = BrowserTestUtils.domWindowClosed(newTabPiPWin);
+      let pipUnloadedNewTab = BrowserTestUtils.waitForEvent(
+        newTabPiPWin,
+        "unload"
+      );
+      let closeButtonNewTab = newTabPiPWin.document.getElementById("close");
+      info("Selecting close button");
+      EventUtils.synthesizeMouseAtCenter(closeButtonNewTab, {}, newTabPiPWin);
+      info("Waiting for PiP window to close");
+      await pipUnloadedNewTab;
+      await pipClosedNewTab;
+
+      ok(
+        bc.forceAppWindowActive,
+        "Force window active should still be true after removing new tab's PiP window"
+      );
+
+      info("is window active: " + bc.isActive);
+
+      let pipClosed = BrowserTestUtils.domWindowClosed(pipWin);
+      let pipUnloaded = BrowserTestUtils.waitForEvent(pipWin, "unload");
+      let closeButton = pipWin.document.getElementById("close");
+      info("Selecting close button");
+      EventUtils.synthesizeMouseAtCenter(closeButton, {}, pipWin);
+      info("Waiting for PiP window to close");
+      await pipUnloaded;
+      await pipClosed;
+
+      ok(
+        !bc.forceAppWindowActive,
+        "Force window active should now be false after removing the last PiP window"
+      );
+
+      info("is window active: " + bc.isActive);
+
+      await BrowserTestUtils.removeTab(newTab);
+    }
+  );
+});
+
+/**
+ * Tests that the forceAppWindowActive flag is correctly set when a tab with PiP enabled is
+ * moved to another window.
+ */
+add_task(async function forceActiveMovePiPToWindow() {
+  let videoID = "with-controls";
+
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE,
+      gBrowser,
+    },
+    async browser => {
+      info("Opening first tab");
+
+      await ensureVideosReady(browser);
+
+      let tab = gBrowser.getTabForBrowser(browser);
+      let bc = browser.ownerGlobal.browsingContext;
+
+      info("is window active: " + bc.isActive);
+
+      ok(!bc.forceAppWindowActive, "Forced window active should be false");
+      info("is window active: " + bc.isActive);
+
+      info("Now opening PiP windows");
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window in first tab.");
+
+      ok(
+        bc.forceAppWindowActive,
+        "Forced window active should be true since PiP is open"
+      );
+      info("is window active: " + bc.isActive);
+
+      let swapDocShellsPromise = BrowserTestUtils.waitForEvent(
+        browser,
+        "SwapDocShells"
+      );
+      let tabClosePromise = BrowserTestUtils.waitForEvent(tab, "TabClose");
+      let tabSwapPiPPromise = BrowserTestUtils.waitForEvent(
+        tab,
+        "TabSwapPictureInPicture"
+      );
+      info("Replacing tab with window");
+      let newWindow = gBrowser.replaceTabWithWindow(tab);
+      let newWinLoadedPromise = BrowserTestUtils.waitForEvent(
+        newWindow,
+        "load"
+      );
+
+      info("Waiting for new window to initialize after swap");
+      await Promise.all([
+        tabSwapPiPPromise,
+        swapDocShellsPromise,
+        tabClosePromise,
+        newWinLoadedPromise,
+      ]);
+
+      let newWindowBC = newWindow.browsingContext;
+      tab = newWindow.gBrowser.selectedTab;
+
+      ok(
+        !bc.forceAppWindowActive,
+        "Force window active should no longer be true after moving the previous tab to a new window"
+      );
+      info("is window active: " + bc.isActive);
+      ok(
+        newWindowBC.forceAppWindowActive,
+        "Force window active should be true for new window since PiP is open"
+      );
+      info("is secondary window active: " + newWindowBC.isActive);
+
+      let pipClosed = BrowserTestUtils.domWindowClosed(pipWin);
+      let pipUnloaded = BrowserTestUtils.waitForEvent(pipWin, "unload");
+      let closeButton = pipWin.document.getElementById("close");
+      info("Selecting close button");
+      EventUtils.synthesizeMouseAtCenter(closeButton, {}, pipWin);
+      info("Waiting for PiP window to close");
+      await pipUnloaded;
+      await pipClosed;
+
+      ok(
+        !newWindowBC.forceAppWindowActive,
+        "Force window active should now be false for new window after removing the last PiP window"
+      );
+      info("is secondary window active: " + newWindowBC.isActive);
+
+      await BrowserTestUtils.removeTab(tab);
+    }
+  );
+});
+
+/**
+ * Tests that the forceAppWindowActive flag is correctly set when multiple PiP
+ * windows are created for a single PiP window.
+ */
+add_task(async function forceActiveMultiPiPSamePage() {
+  let videoID1 = "with-controls";
+  let videoID2 = "no-controls";
+
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE,
+      gBrowser,
+    },
+    async browser => {
+      await ensureVideosReady(browser);
+      let bc = browser.ownerGlobal.browsingContext;
+
+      ok(
+        !bc.forceAppWindowActive,
+        "Forced window active should be false at the start of the test"
+      );
+      info("is window active: " + bc.isActive);
+
+      let pipWin1 = await triggerPictureInPicture(browser, videoID1);
+      ok(pipWin1, "Got Picture-in-Picture window 1.");
+
+      ok(
+        bc.forceAppWindowActive,
+        "Forced window active should be true since PiP is open"
+      );
+      info("is window active: " + bc.isActive);
+
+      let pipWin2 = await triggerPictureInPicture(browser, videoID2);
+      ok(pipWin2, "Got Picture-in-Picture window 2.");
+
+      ok(
+        bc.forceAppWindowActive,
+        "Forced window active should be true after opening another PiP window on the same page"
+      );
+      info("is window active: " + bc.isActive);
+
+      let pipClosed1 = BrowserTestUtils.domWindowClosed(pipWin1);
+      let pipUnloaded1 = BrowserTestUtils.waitForEvent(pipWin1, "unload");
+      let closeButton1 = pipWin1.document.getElementById("close");
+      info("Selecting close button");
+      EventUtils.synthesizeMouseAtCenter(closeButton1, {}, pipWin1);
+      info("Waiting for PiP window to close");
+      await pipUnloaded1;
+      await pipClosed1;
+
+      ok(
+        bc.forceAppWindowActive,
+        "Force window active should still be true after removing PiP window 1"
+      );
+      info("is window active: " + bc.isActive);
+
+      let pipClosed2 = BrowserTestUtils.domWindowClosed(pipWin2);
+      let pipUnloaded2 = BrowserTestUtils.waitForEvent(pipWin2, "unload");
+      let closeButton2 = pipWin2.document.getElementById("close");
+      info("Selecting close button");
+      EventUtils.synthesizeMouseAtCenter(closeButton2, {}, pipWin2);
+      info("Waiting for PiP window to close");
+      await pipUnloaded2;
+      await pipClosed2;
+
+      ok(
+        !bc.forceAppWindowActive,
+        "Force window active should now be false after removing PiP window 2"
+      );
+      info("is window active: " + bc.isActive);
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_playerControls.js b/toolkit/components/pictureinpicture/tests/browser_playerControls.js
new file mode 100644
index 0000000000..9929da597a
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_playerControls.js
@@ -0,0 +1,86 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests functionality of the various controls for the Picture-in-Picture
+ * video window.
+ */
+add_task(async () => {
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      ["media.videocontrols.picture-in-picture.audio-toggle.enabled", true],
+    ],
+  });
+  let videoID = "with-controls";
+  info(`Testing ${videoID} case.`);
+
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE,
+      gBrowser,
+    },
+    async browser => {
+      let waitForVideoEvent = eventType => {
+        return BrowserTestUtils.waitForContentEvent(browser, eventType, true);
+      };
+
+      await ensureVideosReady(browser);
+      await SpecialPowers.spawn(browser, [videoID], async videoID => {
+        await content.document.getElementById(videoID).play();
+      });
+
+      // Open the video in PiP
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+      ok(!(await isVideoPaused(browser, videoID)), "The video is not paused.");
+
+      let playPause = pipWin.document.getElementById("playpause");
+      let audioButton = pipWin.document.getElementById("audio");
+
+      // Try the pause button
+      let pausedPromise = waitForVideoEvent("pause");
+      EventUtils.synthesizeMouseAtCenter(playPause, {}, pipWin);
+      await pausedPromise;
+      ok(await isVideoPaused(browser, videoID), "The video is paused.");
+
+      // Try the play button
+      let playPromise = waitForVideoEvent("play");
+      EventUtils.synthesizeMouseAtCenter(playPause, {}, pipWin);
+      await playPromise;
+      ok(!(await isVideoPaused(browser, videoID)), "The video is playing.");
+
+      // Try the mute button
+      let mutedPromise = waitForVideoEvent("volumechange");
+      ok(!(await isVideoMuted(browser, videoID)), "The audio is playing.");
+      EventUtils.synthesizeMouseAtCenter(audioButton, {}, pipWin);
+      await mutedPromise;
+      ok(await isVideoMuted(browser, videoID), "The audio is muted.");
+
+      // Try the unmute button
+      let unmutedPromise = waitForVideoEvent("volumechange");
+      EventUtils.synthesizeMouseAtCenter(audioButton, {}, pipWin);
+      await unmutedPromise;
+      ok(!(await isVideoMuted(browser, videoID)), "The audio is playing.");
+
+      // Try the unpip button.
+      let pipClosed = BrowserTestUtils.domWindowClosed(pipWin);
+      let unpipButton = pipWin.document.getElementById("unpip");
+      EventUtils.synthesizeMouseAtCenter(unpipButton, {}, pipWin);
+      await pipClosed;
+      ok(!(await isVideoPaused(browser, videoID)), "The video is not paused.");
+
+      // Try the close button.
+      pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+      ok(!(await isVideoPaused(browser, videoID)), "The video is not paused.");
+
+      pipClosed = BrowserTestUtils.domWindowClosed(pipWin);
+      let closeButton = pipWin.document.getElementById("close");
+      EventUtils.synthesizeMouseAtCenter(closeButton, {}, pipWin);
+      await pipClosed;
+      ok(await isVideoPaused(browser, videoID), "The video is paused.");
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_preserveTabPipIconOverlay.js b/toolkit/components/pictureinpicture/tests/browser_preserveTabPipIconOverlay.js
new file mode 100644
index 0000000000..55cd003a2c
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_preserveTabPipIconOverlay.js
@@ -0,0 +1,167 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+requestLongerTimeout(2);
+
+const EVENTUTILS_URL =
+  "chrome://mochikit/content/tests/SimpleTest/EventUtils.js";
+var EventUtils = {};
+
+Services.scriptloader.loadSubScript(EVENTUTILS_URL, EventUtils);
+
+async function detachTab(tab) {
+  let newWindowPromise = new Promise((resolve, reject) => {
+    let observe = (win, topic, data) => {
+      Services.obs.removeObserver(observe, "domwindowopened");
+      resolve(win);
+    };
+    Services.obs.addObserver(observe, "domwindowopened");
+  });
+
+  await EventUtils.synthesizePlainDragAndDrop({
+    srcElement: tab,
+
+    // destElement is null because tab detaching happens due
+    // to a drag'n'drop on an invalid drop target.
+    destElement: null,
+
+    // don't move horizontally because that could cause a tab move
+    // animation, and there's code to prevent a tab detaching if
+    // the dragged tab is released while the animation is running.
+    stepX: 0,
+    stepY: 100,
+  });
+
+  return newWindowPromise;
+}
+
+/**
+ * Tests that tabs dragged between windows with PiP open, the pip attribute stays
+ */
+add_task(async function test_dragging_pip_to_other_window() {
+  // initialize
+  let win1 = await BrowserTestUtils.openNewBrowserWindow();
+  let win2 = await BrowserTestUtils.openNewBrowserWindow();
+
+  let pipTab = await BrowserTestUtils.openNewForegroundTab(
+    win1.gBrowser,
+    TEST_PAGE
+  );
+  let destTab = await BrowserTestUtils.openNewForegroundTab(win2.gBrowser);
+
+  let awaitCloseEventPromise = BrowserTestUtils.waitForEvent(
+    pipTab,
+    "TabClose"
+  );
+  let tabSwapPictureInPictureEventPromise = BrowserTestUtils.waitForEvent(
+    pipTab,
+    "TabSwapPictureInPicture"
+  );
+
+  // Open PiP
+  let videoID = "with-controls";
+  let browser = pipTab.linkedBrowser;
+
+  let pipWin = await triggerPictureInPicture(browser, videoID);
+  ok(pipWin, "Got Picture-in-Picture window.");
+
+  // tear out window
+  let effect = EventUtils.synthesizeDrop(
+    pipTab,
+    destTab,
+    [[{ type: TAB_DROP_TYPE, data: pipTab }]],
+    null,
+    win1,
+    win2
+  );
+  is(effect, "move", "Tab should be moved from win1 to win2.");
+
+  let closeEvent = await awaitCloseEventPromise;
+  let swappedPipTabsEvent = await tabSwapPictureInPictureEventPromise;
+
+  is(
+    closeEvent.detail.adoptedBy,
+    swappedPipTabsEvent.detail,
+    "Pip tab adopted by new tab created when original tab closed"
+  );
+
+  // make sure we reassign the pip tab to the new one
+  pipTab = swappedPipTabsEvent.detail;
+
+  // check PiP attribute
+  ok(pipTab.hasAttribute("pictureinpicture"), "Tab should have PiP attribute");
+
+  // end PiP
+  let pipClosed = BrowserTestUtils.domWindowClosed(pipWin);
+  let closeButton = pipWin.document.getElementById("close");
+  EventUtils.synthesizeMouseAtCenter(closeButton, {}, pipWin);
+  await pipClosed;
+
+  // ensure PiP attribute is gone
+  await TestUtils.waitForCondition(
+    () => !pipTab.hasAttribute("pictureinpicture"),
+    "pictureinpicture attribute was removed"
+  );
+
+  ok(true, "pictureinpicture attribute successfully cleared");
+
+  // close windows
+  await BrowserTestUtils.closeWindow(win1);
+  await BrowserTestUtils.closeWindow(win2);
+});
+
+/**
+ * Tests that tabs torn out into a new window with PiP open, the pip attribute stays
+ */
+add_task(async function test_dragging_pip_into_new_window() {
+  // initialize
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE,
+      gBrowser,
+    },
+    async browser => {
+      // Create PiP
+      let videoID = "with-controls";
+      let pipTab = gBrowser.getTabForBrowser(browser);
+
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+
+      let tabSwapPictureInPictureEventPromise = BrowserTestUtils.waitForEvent(
+        pipTab,
+        "TabSwapPictureInPicture"
+      );
+
+      // tear out into new window
+      let newWin = await detachTab(pipTab);
+
+      let swappedPipTabsEvent = await tabSwapPictureInPictureEventPromise;
+      pipTab = swappedPipTabsEvent.detail;
+
+      // check PiP attribute
+      ok(
+        pipTab.hasAttribute("pictureinpicture"),
+        "Tab should have PiP attribute"
+      );
+
+      // end PiP
+
+      let pipClosed = BrowserTestUtils.domWindowClosed(pipWin);
+      let closeButton = pipWin.document.getElementById("close");
+      EventUtils.synthesizeMouseAtCenter(closeButton, {}, pipWin);
+      await pipClosed;
+
+      // ensure pip attribute is gone
+      await TestUtils.waitForCondition(
+        () => !pipTab.hasAttribute("pictureinpicture"),
+        "pictureinpicture attribute was removed"
+      );
+      ok(true, "pictureinpicture attribute successfully cleared");
+
+      // close windows
+      await BrowserTestUtils.closeWindow(newWin);
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_privateWindow.js b/toolkit/components/pictureinpicture/tests/browser_privateWindow.js
new file mode 100644
index 0000000000..26d051b14a
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_privateWindow.js
@@ -0,0 +1,38 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests that a Picture-in-Picture window opened by a Private browsing
+ * window has the "private" feature set on its window (which is important
+ * for some things, eg: taskbar grouping on Windows).
+ */
+add_task(async () => {
+  for (let videoID of ["with-controls", "no-controls"]) {
+    info(`Testing ${videoID} case.`);
+
+    let privateWin = await BrowserTestUtils.openNewBrowserWindow({
+      private: true,
+    });
+    let pipTab = await BrowserTestUtils.openNewForegroundTab(
+      privateWin.gBrowser,
+      TEST_PAGE
+    );
+    let browser = pipTab.linkedBrowser;
+
+    let pipWin = await triggerPictureInPicture(browser, videoID);
+    ok(pipWin, "Got Picture-in-Picture window.");
+
+    Assert.equal(
+      pipWin.docShell.treeOwner
+        .QueryInterface(Ci.nsIInterfaceRequestor)
+        .getInterface(Ci.nsIAppWindow).chromeFlags &
+        Ci.nsIWebBrowserChrome.CHROME_PRIVATE_WINDOW,
+      Ci.nsIWebBrowserChrome.CHROME_PRIVATE_WINDOW,
+      "Picture-in-Picture window should be marked as private"
+    );
+
+    await BrowserTestUtils.closeWindow(privateWin);
+  }
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_removeVideoElement.js b/toolkit/components/pictureinpicture/tests/browser_removeVideoElement.js
new file mode 100644
index 0000000000..d9622dc3f0
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_removeVideoElement.js
@@ -0,0 +1,84 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests that if a <video> element is being displayed in a
+ * Picture-in-Picture window, that the window closes if that
+ * original <video> is ever removed from the DOM.
+ */
+add_task(async () => {
+  for (let videoID of ["with-controls", "no-controls"]) {
+    info(`Testing ${videoID} case.`);
+
+    await BrowserTestUtils.withNewTab(
+      {
+        url: TEST_PAGE,
+        gBrowser,
+      },
+      async browser => {
+        let pipWin = await triggerPictureInPicture(browser, videoID);
+        Assert.ok(pipWin, "Got PiP window.");
+
+        // First, let's make sure that removing the _other_ video doesn't cause
+        // the special event to fire, nor the PiP window to close.
+        await SpecialPowers.spawn(browser, [videoID], async videoID => {
+          let doc = content.document;
+          let otherVideo = doc.querySelector(`video:not([id="${videoID}"])`);
+          let eventFired = false;
+
+          let listener = e => {
+            eventFired = true;
+          };
+
+          docShell.chromeEventHandler.addEventListener(
+            "MozStopPictureInPicture",
+            listener,
+            {
+              capture: true,
+            }
+          );
+          otherVideo.remove();
+          Assert.ok(
+            !eventFired,
+            "Should not have seen MozStopPictureInPicture for other video"
+          );
+          docShell.chromeEventHandler.removeEventListener(
+            "MozStopPictureInPicture",
+            listener,
+            {
+              capture: true,
+            }
+          );
+        });
+
+        Assert.ok(!pipWin.closed, "PiP window should still be open.");
+
+        await SpecialPowers.spawn(browser, [videoID], async videoID => {
+          let doc = content.document;
+          let video = doc.querySelector(`#${videoID}`);
+
+          let promise = ContentTaskUtils.waitForEvent(
+            docShell.chromeEventHandler,
+            "MozStopPictureInPicture",
+            { capture: true }
+          );
+          video.remove();
+          await promise;
+        });
+
+        try {
+          await BrowserTestUtils.waitForCondition(
+            () => pipWin.closed,
+            "Player window closed."
+          );
+        } finally {
+          if (!pipWin.closed) {
+            await BrowserTestUtils.closeWindow(pipWin);
+          }
+        }
+      }
+    );
+  }
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_resizeVideo.js b/toolkit/components/pictureinpicture/tests/browser_resizeVideo.js
new file mode 100644
index 0000000000..9254ca10cc
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_resizeVideo.js
@@ -0,0 +1,293 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Global values for the left and top edge pixel coordinates. These will be written to
+// during the add_setup function in this test file.
+let gLeftEdge = 0;
+let gTopEdge = 0;
+
+/**
+ * Run the resize test on a player window.
+ *
+ * @param browser (xul:browser)
+ *   The browser that has the source video.
+ *
+ * @param videoID (string)
+ *   The id of the video in the browser to test.
+ *
+ * @param pipWin (player window)
+ *   A player window to run the tests on.
+ *
+ * @param opts (object)
+ *   The options for the test.
+ *
+ *   pinX (boolean):
+ *     If true, the video's X position shouldn't change when resized.
+ *
+ *   pinY (boolean):
+ *     If true, the video's Y position shouldn't change when resized.
+ */
+async function testVideo(browser, videoID, pipWin, { pinX, pinY } = {}) {
+  async function switchVideoSource(src) {
+    let videoResized = BrowserTestUtils.waitForEvent(pipWin, "resize");
+    await ContentTask.spawn(
+      browser,
+      { src, videoID },
+      async ({ src, videoID }) => {
+        let doc = content.document;
+        let video = doc.getElementById(videoID);
+        video.src = src;
+      }
+    );
+    await videoResized;
+  }
+
+  /**
+   * Check the new screen position against the previous one. When
+   * pinX or pinY is true then the top left corner is checked in that
+   * dimension. Otherwise, the bottom right corner is checked.
+   *
+   * The video position is determined by the screen edge it's closest
+   * to, so in the default bottom right its bottom right corner should
+   * match the previous video's bottom right corner. For the top left,
+   * the top left corners should match.
+   */
+  function checkPosition(
+    previousScreenX,
+    previousScreenY,
+    previousWidth,
+    previousHeight,
+    newScreenX,
+    newScreenY,
+    newWidth,
+    newHeight
+  ) {
+    if (pinX || previousScreenX == gLeftEdge) {
+      Assert.equal(
+        previousScreenX,
+        newScreenX,
+        "New video is still in the same X position"
+      );
+    } else {
+      Assert.less(
+        Math.abs(previousScreenX + previousWidth - (newScreenX + newWidth)),
+        2,
+        "New video ends at the same screen X position (within 1 pixel)"
+      );
+    }
+    if (pinY) {
+      Assert.equal(
+        previousScreenY,
+        newScreenY,
+        "New video is still in the same Y position"
+      );
+    } else {
+      Assert.equal(
+        previousScreenY + previousHeight,
+        newScreenY + newHeight,
+        "New video ends at the same screen Y position"
+      );
+    }
+  }
+
+  Assert.ok(pipWin, "Got PiP window.");
+
+  let initialWidth = pipWin.innerWidth;
+  let initialHeight = pipWin.innerHeight;
+  let initialAspectRatio = initialWidth / initialHeight;
+  Assert.equal(
+    Math.floor(initialAspectRatio * 100),
+    177, // 16 / 9 = 1.777777777
+    "Original aspect ratio is 16:9"
+  );
+
+  // Store the window position for later.
+  let initialScreenX = pipWin.mozInnerScreenX;
+  let initialScreenY = pipWin.mozInnerScreenY;
+
+  await switchVideoSource("test-video-cropped.mp4");
+
+  let resizedWidth = pipWin.innerWidth;
+  let resizedHeight = pipWin.innerHeight;
+  let resizedAspectRatio = resizedWidth / resizedHeight;
+  Assert.equal(
+    Math.floor(resizedAspectRatio * 100),
+    133, // 4 / 3 = 1.333333333
+    "Resized aspect ratio is 4:3"
+  );
+  Assert.less(resizedWidth, initialWidth, "Resized video has smaller width");
+  Assert.equal(
+    resizedHeight,
+    initialHeight,
+    "Resized video is the same vertically"
+  );
+
+  let resizedScreenX = pipWin.mozInnerScreenX;
+  let resizedScreenY = pipWin.mozInnerScreenY;
+  checkPosition(
+    initialScreenX,
+    initialScreenY,
+    initialWidth,
+    initialHeight,
+    resizedScreenX,
+    resizedScreenY,
+    resizedWidth,
+    resizedHeight
+  );
+
+  await switchVideoSource("test-video-vertical.mp4");
+
+  let verticalWidth = pipWin.innerWidth;
+  let verticalHeight = pipWin.innerHeight;
+  let verticalAspectRatio = verticalWidth / verticalHeight;
+
+  if (verticalWidth == 136) {
+    // The video is minimun width allowed
+    Assert.equal(
+      Math.floor(verticalAspectRatio * 100),
+      56, // 1 / 2 = 0.5
+      "Vertical aspect ratio is 1:2"
+    );
+  } else {
+    Assert.equal(
+      Math.floor(verticalAspectRatio * 100),
+      50, // 1 / 2 = 0.5
+      "Vertical aspect ratio is 1:2"
+    );
+  }
+
+  Assert.less(verticalWidth, resizedWidth, "Vertical video width shrunk");
+  Assert.equal(
+    verticalHeight,
+    initialHeight,
+    "Vertical video height matches previous height"
+  );
+
+  let verticalScreenX = pipWin.mozInnerScreenX;
+  let verticalScreenY = pipWin.mozInnerScreenY;
+  checkPosition(
+    resizedScreenX,
+    resizedScreenY,
+    resizedWidth,
+    resizedHeight,
+    verticalScreenX,
+    verticalScreenY,
+    verticalWidth,
+    verticalHeight
+  );
+
+  await switchVideoSource("test-video.mp4");
+
+  let restoredWidth = pipWin.innerWidth;
+  let restoredHeight = pipWin.innerHeight;
+  let restoredAspectRatio = restoredWidth / restoredHeight;
+  Assert.equal(
+    Math.floor(restoredAspectRatio * 100),
+    177,
+    "Restored aspect ratio is still 16:9"
+  );
+  Assert.less(
+    Math.abs(initialWidth - pipWin.innerWidth),
+    2,
+    "Restored video has its original width"
+  );
+  Assert.equal(
+    initialHeight,
+    pipWin.innerHeight,
+    "Restored video has its original height"
+  );
+
+  let restoredScreenX = pipWin.mozInnerScreenX;
+  let restoredScreenY = pipWin.mozInnerScreenY;
+  checkPosition(
+    initialScreenX,
+    initialScreenY,
+    initialWidth,
+    initialHeight,
+    restoredScreenX,
+    restoredScreenY,
+    restoredWidth,
+    restoredHeight
+  );
+}
+
+add_setup(async () => {
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE,
+      gBrowser,
+    },
+    async browser => {
+      // Reset the saved PiP location to top-left edge of the screen, wherever
+      // that may be. We record the top-left edge of the screen coordinates into
+      // global variables to do later coordinate comparisons after resizes.
+      let clearWin = await triggerPictureInPicture(browser, "with-controls");
+      let initialScreenX = clearWin.mozInnerScreenX;
+      let initialScreenY = clearWin.mozInnerScreenY;
+      let PiPScreen = PictureInPicture.getWorkingScreen(
+        initialScreenX,
+        initialScreenY
+      );
+      [gLeftEdge, gTopEdge] = PictureInPicture.getAvailScreenSize(PiPScreen);
+      clearWin.moveTo(gLeftEdge, gTopEdge);
+
+      await BrowserTestUtils.closeWindow(clearWin);
+    }
+  );
+});
+
+/**
+ * Tests that if a <video> element is resized the Picture-in-Picture window
+ * will be resized to match the new dimensions.
+ */
+add_task(async () => {
+  for (let videoID of ["with-controls", "no-controls"]) {
+    info(`Testing ${videoID} case.`);
+
+    await BrowserTestUtils.withNewTab(
+      {
+        url: TEST_PAGE,
+        gBrowser,
+      },
+      async browser => {
+        let pipWin = await triggerPictureInPicture(browser, videoID);
+
+        await testVideo(browser, videoID, pipWin);
+
+        pipWin.moveTo(gLeftEdge, gTopEdge);
+
+        await testVideo(browser, videoID, pipWin, { pinX: true, pinY: true });
+
+        await BrowserTestUtils.closeWindow(pipWin);
+      }
+    );
+  }
+});
+
+/**
+ * Tests that the RTL video starts on the left and is pinned in the X dimension.
+ */
+add_task(async () => {
+  await SpecialPowers.pushPrefEnv({ set: [["intl.l10n.pseudo", "bidi"]] });
+
+  for (let videoID of ["with-controls", "no-controls"]) {
+    info(`Testing ${videoID} case.`);
+
+    await BrowserTestUtils.withNewTab(
+      {
+        url: TEST_PAGE,
+        gBrowser,
+      },
+      async browser => {
+        let pipWin = await triggerPictureInPicture(browser, videoID);
+
+        await testVideo(browser, videoID, pipWin, { pinX: true });
+
+        await BrowserTestUtils.closeWindow(pipWin);
+      }
+    );
+  }
+  await SpecialPowers.popPrefEnv();
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_reversePiP.js b/toolkit/components/pictureinpicture/tests/browser_reversePiP.js
new file mode 100644
index 0000000000..a8ae20166f
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_reversePiP.js
@@ -0,0 +1,145 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ *  Tests that the PiP toggle button is not flipped
+ *  on certain websites (such as whereby.com).
+ */
+add_task(async () => {
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: TEST_ROOT + "test-reversed.html",
+    },
+    async browser => {
+      await ensureVideosReady(browser);
+
+      let videoID = "reversed";
+
+      // Test the toggle button
+      await prepareForToggleClick(browser, videoID);
+
+      // Hover the mouse over the video to reveal the toggle.
+      await BrowserTestUtils.synthesizeMouseAtCenter(
+        `#${videoID}`,
+        {
+          type: "mousemove",
+        },
+        browser
+      );
+      await BrowserTestUtils.synthesizeMouseAtCenter(
+        `#${videoID}`,
+        {
+          type: "mouseover",
+        },
+        browser
+      );
+
+      let toggleFlippedAttribute = await SpecialPowers.spawn(
+        browser,
+        [videoID],
+        async videoID => {
+          let video = content.document.getElementById(videoID);
+          let shadowRoot = video.openOrClosedShadowRoot;
+          let controlsOverlay = shadowRoot.querySelector(".controlsOverlay");
+
+          await ContentTaskUtils.waitForCondition(() => {
+            return controlsOverlay.classList.contains("hovering");
+          }, "Waiting for the hovering state to be set on the video.");
+
+          return shadowRoot.firstChild.getAttribute("flipped");
+        }
+      );
+
+      // The "flipped" attribute should be set on the toggle button (when applicable).
+      Assert.equal(toggleFlippedAttribute, "true");
+    }
+  );
+});
+
+/**
+ * Tests that the "This video is playing in Picture-in-Picture" message
+ * as well as the video playing in PiP are both not flipped on certain sites
+ * (such as whereby.com)
+ */
+add_task(async () => {
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: TEST_ROOT + "test-reversed.html",
+    },
+    async browser => {
+      /**
+       * A helper function used to get the "flipped" attribute of the video's shadowRoot's first child.
+       * @param {Element} browser The <xul:browser> hosting the <video>
+       * @param {String} videoID The ID of the video being checked
+       */
+      async function getFlippedAttribute(browser, videoID) {
+        let videoFlippedAttribute = await SpecialPowers.spawn(
+          browser,
+          [videoID],
+          async videoID => {
+            let video = content.document.getElementById(videoID);
+            let shadowRoot = video.openOrClosedShadowRoot;
+            return shadowRoot.firstChild.getAttribute("flipped");
+          }
+        );
+        return videoFlippedAttribute;
+      }
+
+      /**
+       * A helper function that returns the transform.a of the video being played in PiP.
+       * @param {Element} playerBrowser The <xul:browser> of the PiP window
+       */
+      async function getPiPVideoTransform(playerBrowser) {
+        let pipVideoTransform = await SpecialPowers.spawn(
+          playerBrowser,
+          [],
+          async () => {
+            let video = content.document.querySelector("video");
+            return video.getTransformToViewport().a;
+          }
+        );
+        return pipVideoTransform;
+      }
+
+      await ensureVideosReady(browser);
+
+      let videoID = "reversed";
+
+      let videoFlippedAttribute = await getFlippedAttribute(browser, videoID);
+      Assert.equal(videoFlippedAttribute, null); // The "flipped" attribute should not be set initially.
+
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+
+      videoFlippedAttribute = await getFlippedAttribute(browser, "reversed");
+      Assert.equal(videoFlippedAttribute, "true"); // The "flipped" value should be set once the PiP window is opened (when applicable).
+
+      let playerBrowser = pipWin.document.getElementById("browser");
+      let pipVideoTransform = await getPiPVideoTransform(playerBrowser);
+      Assert.equal(pipVideoTransform, -1);
+
+      await ensureMessageAndClosePiP(browser, videoID, pipWin, false);
+
+      videoFlippedAttribute = await getFlippedAttribute(browser, "reversed");
+      Assert.equal(videoFlippedAttribute, null); // The "flipped" attribute should be removed after closing PiP.
+
+      // Now we want to test that regular (not-reversed) videos are unaffected
+      videoID = "not-reversed";
+      videoFlippedAttribute = await getFlippedAttribute(browser, videoID);
+      Assert.equal(videoFlippedAttribute, null);
+
+      pipWin = await triggerPictureInPicture(browser, videoID);
+
+      videoFlippedAttribute = await getFlippedAttribute(browser, videoID);
+      Assert.equal(videoFlippedAttribute, null);
+
+      playerBrowser = pipWin.document.getElementById("browser");
+      pipVideoTransform = await getPiPVideoTransform(playerBrowser);
+
+      await ensureMessageAndClosePiP(browser, videoID, pipWin, false);
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_saveLastPiPLoc.js b/toolkit/components/pictureinpicture/tests/browser_saveLastPiPLoc.js
new file mode 100644
index 0000000000..02c006db4a
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_saveLastPiPLoc.js
@@ -0,0 +1,398 @@
+/* Any copyright is dedicated to the Public Domain.
+http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * This function tests that the browser saves the last location of size of
+ * the PiP window and will open the next PiP window in the same location
+ * with the size. It adjusts for aspect ratio by keeping the same height and
+ * adjusting the width of the PiP window.
+ */
+async function doTest() {
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE,
+      gBrowser,
+    },
+    // Function to switch video source.
+    async browser => {
+      async function switchVideoSource(src) {
+        let videoResized = BrowserTestUtils.waitForEvent(pipWin, "resize");
+        await ContentTask.spawn(browser, { src }, async ({ src }) => {
+          let doc = content.document;
+          let video = doc.getElementById("with-controls");
+          video.src = src;
+        });
+        await videoResized;
+      }
+
+      function getAvailScreenSize(screen) {
+        let screenLeft = {},
+          screenTop = {},
+          screenWidth = {},
+          screenHeight = {};
+        screen.GetAvailRectDisplayPix(
+          screenLeft,
+          screenTop,
+          screenWidth,
+          screenHeight
+        );
+
+        // We have to divide these dimensions by the CSS scale factor for the
+        // display in order for the video to be positioned correctly on displays
+        // that are not at a 1.0 scaling.
+        let scaleFactor =
+          screen.contentsScaleFactor / screen.defaultCSSScaleFactor;
+        screenWidth.value *= scaleFactor;
+        screenHeight.value *= scaleFactor;
+        screenLeft.value *= scaleFactor;
+        screenTop.value *= scaleFactor;
+
+        return [
+          screenLeft.value,
+          screenTop.value,
+          screenWidth.value,
+          screenHeight.value,
+        ];
+      }
+
+      let screen = Cc["@mozilla.org/gfx/screenmanager;1"]
+        .getService(Ci.nsIScreenManager)
+        .screenForRect(1, 1, 1, 1);
+
+      let [defaultX, defaultY, defaultWidth, defaultHeight] =
+        getAvailScreenSize(screen);
+
+      // Default size of PiP window
+      let rightEdge = defaultX + defaultWidth;
+      let bottomEdge = defaultY + defaultHeight;
+
+      // tab height
+      // Used only for Linux as the PiP window has a tab
+      let tabHeight = 35;
+
+      // clear already saved information
+      clearSavedPosition();
+
+      // Open PiP
+      let pipWin = await triggerPictureInPicture(browser, "with-controls");
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      let defaultPiPWidth = pipWin.innerWidth;
+      let defaultPiPHeight = pipWin.innerHeight;
+
+      // Check that it is opened at default location
+      isfuzzy(
+        pipWin.screenX,
+        rightEdge - defaultPiPWidth,
+        ACCEPTABLE_DIFFERENCE,
+        "Default PiP X location"
+      );
+      if (AppConstants.platform == "linux") {
+        isfuzzy(
+          pipWin.screenY,
+          bottomEdge - defaultPiPHeight - tabHeight,
+          ACCEPTABLE_DIFFERENCE,
+          "Default PiP Y location"
+        );
+      } else {
+        isfuzzy(
+          pipWin.screenY,
+          bottomEdge - defaultPiPHeight,
+          ACCEPTABLE_DIFFERENCE,
+          "Default PiP Y location"
+        );
+      }
+      isfuzzy(
+        pipWin.innerHeight,
+        defaultPiPHeight,
+        ACCEPTABLE_DIFFERENCE,
+        "Default PiP height"
+      );
+      isfuzzy(
+        pipWin.innerWidth,
+        defaultPiPWidth,
+        ACCEPTABLE_DIFFERENCE,
+        "Default PiP width"
+      );
+
+      let top = defaultY;
+      let left = defaultX;
+      pipWin.moveTo(left, top);
+      let height = pipWin.innerHeight / 2;
+      let width = pipWin.innerWidth / 2;
+      pipWin.resizeTo(width, height);
+
+      // CLose first PiP window and open another
+      await ensureMessageAndClosePiP(browser, "with-controls", pipWin, true);
+      pipWin = await triggerPictureInPicture(browser, "with-controls");
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      // PiP is opened at 0, 0 with size 1/4 default width and 1/4 default height
+      isfuzzy(
+        pipWin.screenX,
+        left,
+        ACCEPTABLE_DIFFERENCE,
+        "Opened at last X location"
+      );
+      isfuzzy(
+        pipWin.screenY,
+        top,
+        ACCEPTABLE_DIFFERENCE,
+        "Opened at last Y location"
+      );
+      isfuzzy(
+        pipWin.innerHeight,
+        height,
+        ACCEPTABLE_DIFFERENCE,
+        "Opened with 1/2 default height"
+      );
+      isfuzzy(
+        pipWin.innerWidth,
+        width,
+        ACCEPTABLE_DIFFERENCE,
+        "Opened with 1/2 default width"
+      );
+
+      // Mac and Linux did not allow moving to coordinates offscreen so this
+      // test is skipped on those platforms
+      if (AppConstants.platform == "win") {
+        // Move to -1111, -1111 and adjust size to 1/4 width and 1/4 height
+        left = -11111;
+        top = -11111;
+        pipWin.moveTo(left, top);
+        pipWin.resizeTo(pipWin.innerWidth / 4, pipWin.innerHeight / 4);
+
+        await ensureMessageAndClosePiP(browser, "with-controls", pipWin, true);
+        pipWin = await triggerPictureInPicture(browser, "with-controls");
+        ok(pipWin, "Got Picture-in-Picture window.");
+
+        // because the coordinates are off screen, the default size and location will be used
+        isfuzzy(
+          pipWin.screenX,
+          rightEdge - defaultPiPWidth,
+          ACCEPTABLE_DIFFERENCE,
+          "Opened at default X location"
+        );
+        isfuzzy(
+          pipWin.screenY,
+          bottomEdge - defaultPiPHeight,
+          ACCEPTABLE_DIFFERENCE,
+          "Opened at default Y location"
+        );
+        isfuzzy(
+          pipWin.innerWidth,
+          defaultPiPWidth,
+          ACCEPTABLE_DIFFERENCE,
+          "Opened at default PiP width"
+        );
+        isfuzzy(
+          pipWin.innerHeight,
+          defaultPiPHeight,
+          ACCEPTABLE_DIFFERENCE,
+          "Opened at default PiP height"
+        );
+      }
+
+      // Linux doesn't handle switching the video source well and it will
+      // cause the tests to failed in unexpected ways. Possibly caused by
+      // bug 1594223 https://bugzilla.mozilla.org/show_bug.cgi?id=1594223
+      if (AppConstants.platform != "linux") {
+        // Save width and height for when aspect ratio is changed
+        height = pipWin.innerHeight;
+        width = pipWin.innerWidth;
+
+        left = 200;
+        top = 100;
+        pipWin.moveTo(left, top);
+
+        // Now switch the video so the video ratio is different
+        await switchVideoSource("test-video-cropped.mp4");
+        await ensureMessageAndClosePiP(browser, "with-controls", pipWin, true);
+        pipWin = await triggerPictureInPicture(browser, "with-controls");
+        ok(pipWin, "Got Picture-in-Picture window.");
+
+        isfuzzy(
+          pipWin.screenX,
+          left,
+          ACCEPTABLE_DIFFERENCE,
+          "Opened at last X location"
+        );
+        isfuzzy(
+          pipWin.screenY,
+          top,
+          ACCEPTABLE_DIFFERENCE,
+          "Opened at last Y location"
+        );
+        isfuzzy(
+          pipWin.innerHeight,
+          height,
+          ACCEPTABLE_DIFFERENCE,
+          "Opened height with previous width"
+        );
+        isfuzzy(
+          pipWin.innerWidth,
+          height * (pipWin.innerWidth / pipWin.innerHeight),
+          ACCEPTABLE_DIFFERENCE,
+          "Width is changed to adjust for aspect ration"
+        );
+
+        left = 300;
+        top = 300;
+        pipWin.moveTo(left, top);
+        pipWin.resizeTo(defaultPiPWidth / 2, defaultPiPHeight / 2);
+
+        // Save height for when aspect ratio is changed
+        height = pipWin.innerHeight;
+
+        // Now switch the video so the video ratio is different
+        await switchVideoSource("test-video.mp4");
+        await ensureMessageAndClosePiP(browser, "with-controls", pipWin, true);
+        pipWin = await triggerPictureInPicture(browser, "with-controls");
+        ok(pipWin, "Got Picture-in-Picture window.");
+
+        isfuzzy(
+          pipWin.screenX,
+          left,
+          ACCEPTABLE_DIFFERENCE,
+          "Opened at last X location"
+        );
+        isfuzzy(
+          pipWin.screenY,
+          top,
+          ACCEPTABLE_DIFFERENCE,
+          "Opened at last Y location"
+        );
+        isfuzzy(
+          pipWin.innerHeight,
+          height,
+          ACCEPTABLE_DIFFERENCE,
+          "Opened with previous height"
+        );
+        isfuzzy(
+          pipWin.innerWidth,
+          height * (pipWin.innerWidth / pipWin.innerHeight),
+          ACCEPTABLE_DIFFERENCE,
+          "Width is changed to adjust for aspect ration"
+        );
+      }
+
+      // Move so that part of PiP is off screen (bottom right)
+
+      left = rightEdge - Math.round((3 * pipWin.innerWidth) / 4);
+      top = bottomEdge - Math.round((3 * pipWin.innerHeight) / 4);
+
+      let movePromise = BrowserTestUtils.waitForEvent(
+        pipWin.windowRoot,
+        "MozUpdateWindowPos"
+      );
+      pipWin.moveTo(left, top);
+      await movePromise;
+
+      await ensureMessageAndClosePiP(browser, "with-controls", pipWin, true);
+      pipWin = await triggerPictureInPicture(browser, "with-controls");
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      // Redefine top and left to where the PiP windop will open
+      left = rightEdge - pipWin.innerWidth;
+      top = bottomEdge - pipWin.innerHeight;
+
+      // await new Promise(r => setTimeout(r, 5000));
+      // PiP is opened bottom right but not off screen
+      isfuzzy(
+        pipWin.screenX,
+        left,
+        ACCEPTABLE_DIFFERENCE,
+        "Opened at last X location but shifted back on screen"
+      );
+      if (AppConstants.platform == "linux") {
+        isfuzzy(
+          pipWin.screenY,
+          top - tabHeight,
+          ACCEPTABLE_DIFFERENCE,
+          "Opened at last Y location but shifted back on screen"
+        );
+      } else {
+        isfuzzy(
+          pipWin.screenY,
+          top,
+          ACCEPTABLE_DIFFERENCE,
+          "Opened at last Y location but shifted back on screen"
+        );
+      }
+
+      // Move so that part of PiP is off screen (top left)
+      left = defaultX - Math.round(pipWin.innerWidth / 4);
+      top = defaultY - Math.round(pipWin.innerHeight / 4);
+
+      movePromise = BrowserTestUtils.waitForEvent(
+        pipWin.windowRoot,
+        "MozUpdateWindowPos"
+      );
+      pipWin.moveTo(left, top);
+      await movePromise;
+
+      await ensureMessageAndClosePiP(browser, "with-controls", pipWin, true);
+      pipWin = await triggerPictureInPicture(browser, "with-controls");
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      // PiP is opened top left on screen
+      isfuzzy(
+        pipWin.screenX,
+        defaultX,
+        ACCEPTABLE_DIFFERENCE,
+        "Opened at last X location but shifted back on screen"
+      );
+      isfuzzy(
+        pipWin.screenY,
+        defaultY,
+        ACCEPTABLE_DIFFERENCE,
+        "Opened at last Y location but shifted back on screen"
+      );
+
+      if (AppConstants.platform != "linux") {
+        // test that if video is on right edge and new video with smaller width
+        // is opened next, it is still on the right edge
+        left = rightEdge - pipWin.innerWidth;
+        top = Math.round(bottomEdge / 4);
+
+        pipWin.moveTo(left, top);
+
+        // Used to ensure that video width decreases for next PiP window
+        width = pipWin.innerWidth;
+        isfuzzy(
+          pipWin.innerWidth + pipWin.screenX,
+          rightEdge,
+          ACCEPTABLE_DIFFERENCE,
+          "Video is on right edge before video is changed"
+        );
+
+        // Now switch the video so the video width is smaller
+        await switchVideoSource("test-video-cropped.mp4");
+        await ensureMessageAndClosePiP(browser, "with-controls", pipWin, true);
+        pipWin = await triggerPictureInPicture(browser, "with-controls");
+        ok(pipWin, "Got Picture-in-Picture window.");
+
+        ok(pipWin.innerWidth < width, "New video width is smaller");
+        isfuzzy(
+          pipWin.innerWidth + pipWin.screenX,
+          rightEdge,
+          ACCEPTABLE_DIFFERENCE,
+          "Video is on right edge after video is changed"
+        );
+      }
+
+      await ensureMessageAndClosePiP(browser, "with-controls", pipWin, true);
+    }
+  );
+}
+
+add_task(async function test_pip_save_last_loc() {
+  await doTest();
+});
+
+add_task(async function test_pip_save_last_loc_with_os_zoom() {
+  await SpecialPowers.pushPrefEnv({ set: [["ui.textScaleFactor", 120]] });
+  await doTest();
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_shortcutsAfterFocus.js b/toolkit/components/pictureinpicture/tests/browser_shortcutsAfterFocus.js
new file mode 100644
index 0000000000..7d40664df4
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_shortcutsAfterFocus.js
@@ -0,0 +1,67 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests functionality of arrow keys in Picture-in-Picture window
+ * for seeking and volume adjustment
+ */
+add_task(async () => {
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      [
+        "media.videocontrols.picture-in-picture.keyboard-controls.enabled",
+        true,
+      ],
+    ],
+  });
+  let videoID = "with-controls";
+  info(`Testing ${videoID} case.`);
+
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE,
+      gBrowser,
+    },
+    async browser => {
+      let waitForVideoEvent = eventType => {
+        return BrowserTestUtils.waitForContentEvent(browser, eventType, true);
+      };
+
+      await ensureVideosReady(browser);
+
+      // Open the video in PiP
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      // run the next tests 4 times to ensure that they work for each PiP button, including none
+      for (var i = 0; i < 4; i++) {
+        // Try seek forward
+        let seekedForwardPromise = waitForVideoEvent("seeked");
+        EventUtils.synthesizeKey("KEY_ArrowRight", {}, pipWin);
+        ok(await seekedForwardPromise, "The time seeked forward");
+
+        // Try seek backward
+        let seekedBackwardPromise = waitForVideoEvent("seeked");
+        EventUtils.synthesizeKey("KEY_ArrowLeft", {}, pipWin);
+        ok(await seekedBackwardPromise, "The time seeked backward");
+
+        // Try volume down
+        let volumeDownPromise = waitForVideoEvent("volumechange");
+        EventUtils.synthesizeKey("KEY_ArrowDown", {}, pipWin);
+        ok(await volumeDownPromise, "The volume went down");
+
+        // Try volume up
+        let volumeUpPromise = waitForVideoEvent("volumechange");
+        EventUtils.synthesizeKey("KEY_ArrowUp", {}, pipWin);
+        ok(await volumeUpPromise, "The volume went up");
+
+        // Tab to get to the next button
+        EventUtils.synthesizeKey("KEY_Tab", {}, pipWin);
+      }
+
+      await BrowserTestUtils.closeWindow(pipWin);
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_showMessage.js b/toolkit/components/pictureinpicture/tests/browser_showMessage.js
new file mode 100644
index 0000000000..24d8347a7f
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_showMessage.js
@@ -0,0 +1,29 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests that triggering Picture-in-Picture causes the Picture-in-Picture
+ * window to be opened, and a message to be displayed in the original video
+ * player area. Also ensures that once the Picture-in-Picture window is closed,
+ * the video goes back to the original state.
+ */
+add_task(async () => {
+  for (let videoID of ["with-controls", "no-controls"]) {
+    info(`Testing ${videoID} case.`);
+
+    await BrowserTestUtils.withNewTab(
+      {
+        url: TEST_PAGE,
+        gBrowser,
+      },
+      async browser => {
+        let pipWin = await triggerPictureInPicture(browser, videoID);
+        ok(pipWin, "Got Picture-in-Picture window.");
+
+        await ensureMessageAndClosePiP(browser, videoID, pipWin, false);
+      }
+    );
+  }
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_smallVideoLayout.js b/toolkit/components/pictureinpicture/tests/browser_smallVideoLayout.js
new file mode 100644
index 0000000000..84866fba3e
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_smallVideoLayout.js
@@ -0,0 +1,210 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests that the Picture-in-Picture toggle is hidden when videos
+ * are laid out with dimensions smaller than MIN_VIDEO_DIMENSION (a
+ * constant that is also defined in videocontrols.js).
+ */
+add_task(async () => {
+  // Most of the Picture-in-Picture tests run with the always-show
+  // preference set to true to avoid the toggle visibility heuristics.
+  // Since this test actually exercises those heuristics, we have
+  // to temporarily disable that pref.
+  //
+  // We also reduce the minimum video length for displaying the toggle
+  // to 5 seconds to avoid having to include or generate a 45 second long
+  // video (which is the default minimum length).
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      [
+        "media.videocontrols.picture-in-picture.video-toggle.always-show",
+        false,
+      ],
+      ["media.videocontrols.picture-in-picture.video-toggle.min-video-secs", 5],
+    ],
+  });
+
+  // This is the minimum size of the video in either width or height for
+  // which we will show the toggle. See videocontrols.js.
+  const MIN_VIDEO_DIMENSION = 140; // pixels
+
+  for (let videoID of ["with-controls", "no-controls"]) {
+    info(`Testing ${videoID} case.`);
+
+    await BrowserTestUtils.withNewTab(
+      {
+        url: TEST_PAGE_WITH_SOUND,
+        gBrowser,
+      },
+      async browser => {
+        // Shrink the video down to less than MIN_VIDEO_DIMENSION.
+        let targetWidth = MIN_VIDEO_DIMENSION - 1;
+        await SpecialPowers.spawn(
+          browser,
+          [videoID, targetWidth],
+          async (videoID, targetWidth) => {
+            let video = content.document.getElementById(videoID);
+            let shadowRoot = video.openOrClosedShadowRoot;
+            let resizePromise = ContentTaskUtils.waitForEvent(
+              shadowRoot.firstChild,
+              "resizevideocontrols"
+            );
+            video.style.width = targetWidth + "px";
+            await resizePromise;
+          }
+        );
+
+        // The toggle should be hidden.
+        await testToggleHelper(browser, videoID, false);
+
+        // Now re-expand the video.
+        await SpecialPowers.spawn(browser, [videoID], async videoID => {
+          let video = content.document.getElementById(videoID);
+          let shadowRoot = video.openOrClosedShadowRoot;
+          let resizePromise = ContentTaskUtils.waitForEvent(
+            shadowRoot.firstChild,
+            "resizevideocontrols"
+          );
+          video.style.width = "";
+          await resizePromise;
+        });
+
+        // The toggle should be visible.
+        await testToggleHelper(browser, videoID, true);
+      }
+    );
+  }
+});
+
+/**
+ * Tests that when using the experimental toggle variations, videos
+ * under 320px width are given the "small-video" attribute.
+ */
+add_task(async () => {
+  const TOGGLE_SMALL = {
+    rootID: "pictureInPictureToggle",
+    stages: {
+      hoverVideo: {
+        opacities: {
+          ".pip-wrapper": DEFAULT_TOGGLE_OPACITY,
+        },
+        hidden: [],
+      },
+
+      hoverToggle: {
+        opacities: {
+          ".pip-wrapper": 1.0,
+        },
+        hidden: [".pip-expanded"],
+      },
+    },
+  };
+
+  const TOGGLE_LARGE = {
+    rootID: "pictureInPictureToggle",
+    stages: {
+      hoverVideo: {
+        opacities: {
+          ".pip-small": 0.0,
+          ".pip-wrapper": DEFAULT_TOGGLE_OPACITY,
+          ".pip-expanded": 0.0,
+        },
+        hidden: [".pip-explainer", ".pip-icon-label > .pip-icon"],
+      },
+      hoverToggle: {
+        opacities: {
+          ".pip-small": 0.0,
+          ".pip-wrapper": 1.0,
+        },
+        hidden: [
+          ".pip-explainer",
+          ".pip-icon-label > .pip-icon",
+          ".pip-expanded",
+        ],
+      },
+    },
+  };
+
+  // Most of the Picture-in-Picture tests run with the always-show
+  // preference set to true to avoid the toggle visibility heuristics.
+  // Since this test actually exercises those heuristics, we have
+  // to temporarily disable that pref.
+  //
+  // We also reduce the minimum video length for displaying the toggle
+  // to 5 seconds to avoid having to include or generate a 45 second long
+  // video (which is the default minimum length).
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      [
+        "media.videocontrols.picture-in-picture.video-toggle.always-show",
+        false,
+      ],
+      ["media.videocontrols.picture-in-picture.video-toggle.min-video-secs", 5],
+      ["media.videocontrols.picture-in-picture.video-toggle.mode", 1],
+    ],
+  });
+
+  // Videos that are thinner than MIN_VIDEO_WIDTH should have the small-video
+  // attribute set on the experimental toggle.
+  const MIN_VIDEO_WIDTH = 320; // pixels
+
+  for (let videoID of ["with-controls", "no-controls"]) {
+    info(`Testing ${videoID} case.`);
+
+    await BrowserTestUtils.withNewTab(
+      {
+        url: TEST_PAGE_WITH_SOUND,
+        gBrowser,
+      },
+      async browser => {
+        // Shrink the video down to less than MIN_VIDEO_WIDTH.
+        let targetWidth = MIN_VIDEO_WIDTH - 1;
+        let isSmallVideo = await SpecialPowers.spawn(
+          browser,
+          [videoID, targetWidth],
+          async (videoID, targetWidth) => {
+            let video = content.document.getElementById(videoID);
+            let shadowRoot = video.openOrClosedShadowRoot;
+            let resizePromise = ContentTaskUtils.waitForEvent(
+              shadowRoot.firstChild,
+              "resizevideocontrols"
+            );
+            video.style.width = targetWidth + "px";
+            await resizePromise;
+            let toggle = shadowRoot.getElementById("pictureInPictureToggle");
+            return toggle.hasAttribute("small-video");
+          }
+        );
+
+        Assert.ok(isSmallVideo, "Video should have small-video attribute");
+
+        await testToggleHelper(browser, videoID, true, undefined, TOGGLE_SMALL);
+
+        // Now re-expand the video.
+        isSmallVideo = await SpecialPowers.spawn(
+          browser,
+          [videoID],
+          async videoID => {
+            let video = content.document.getElementById(videoID);
+            let shadowRoot = video.openOrClosedShadowRoot;
+            let resizePromise = ContentTaskUtils.waitForEvent(
+              shadowRoot.firstChild,
+              "resizevideocontrols"
+            );
+            video.style.width = "";
+            await resizePromise;
+            let toggle = shadowRoot.getElementById("pictureInPictureToggle");
+            return toggle.hasAttribute("small-video");
+          }
+        );
+
+        Assert.ok(!isSmallVideo, "Video should not have small-video attribute");
+
+        await testToggleHelper(browser, videoID, true, undefined, TOGGLE_LARGE);
+      }
+    );
+  }
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_stripVideoStyles.js b/toolkit/components/pictureinpicture/tests/browser_stripVideoStyles.js
new file mode 100644
index 0000000000..10eb8f43ea
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_stripVideoStyles.js
@@ -0,0 +1,49 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests that <video>'s with styles on the element don't have those
+ * styles cloned over into the <video> that's inserted into the
+ * player window.
+ */
+add_task(async () => {
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE,
+      gBrowser,
+    },
+    async browser => {
+      let styles = {
+        padding: "15px",
+        border: "5px solid red",
+        margin: "3px",
+        position: "absolute",
+      };
+
+      await SpecialPowers.spawn(browser, [styles], async videoStyles => {
+        let video = content.document.getElementById("no-controls");
+        for (let styleProperty in videoStyles) {
+          video.style[styleProperty] = videoStyles[styleProperty];
+        }
+      });
+
+      let pipWin = await triggerPictureInPicture(browser, "no-controls");
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      let playerBrowser = pipWin.document.getElementById("browser");
+      await SpecialPowers.spawn(playerBrowser, [styles], async videoStyles => {
+        let video = content.document.querySelector("video");
+        for (let styleProperty in videoStyles) {
+          Assert.equal(
+            video.style[styleProperty],
+            "",
+            `Style ${styleProperty} should not be set`
+          );
+        }
+      });
+      await BrowserTestUtils.closeWindow(pipWin);
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_subtitles_settings_panel.js b/toolkit/components/pictureinpicture/tests/browser_subtitles_settings_panel.js
new file mode 100644
index 0000000000..3c0e839126
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_subtitles_settings_panel.js
@@ -0,0 +1,273 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests that pressing the Escape key will close the subtitles settings panel and
+ * not remove focus if activated via the mouse.
+ */
+add_task(async function test_closePanelESCMouseFocus() {
+  clearSavedPosition();
+
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE_WITH_WEBVTT,
+      gBrowser,
+    },
+    async browser => {
+      await SpecialPowers.pushPrefEnv({
+        set: [
+          [
+            "media.videocontrols.picture-in-picture.display-text-tracks.enabled",
+            true,
+          ],
+          [
+            "media.videocontrols.picture-in-picture.display-text-tracks.size",
+            "medium",
+          ],
+        ],
+      });
+
+      let videoID = "with-controls";
+
+      await ensureVideosReady(browser);
+      await prepareVideosAndWebVTTTracks(browser, videoID);
+      await SpecialPowers.spawn(browser, [videoID], async videoID => {
+        await content.document.getElementById(videoID).play();
+      });
+
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      // Resize PiP window so that subtitles button is visible
+      let resizePromise = BrowserTestUtils.waitForEvent(pipWin, "resize");
+      pipWin.resizeTo(640, 360);
+      await resizePromise;
+
+      let subtitlesButton = pipWin.document.getElementById("closed-caption");
+      Assert.ok(subtitlesButton, "Subtitles button found");
+
+      let subtitlesPanel = pipWin.document.getElementById("settings");
+      let panelVisiblePromise = BrowserTestUtils.waitForCondition(
+        () => BrowserTestUtils.is_visible(subtitlesPanel),
+        "Wait for panel to be visible"
+      );
+
+      EventUtils.synthesizeMouseAtCenter(subtitlesButton, {}, pipWin);
+
+      await panelVisiblePromise;
+
+      let audioButton = pipWin.document.getElementById("audio");
+      audioButton.focus();
+
+      let panelHiddenPromise = BrowserTestUtils.waitForCondition(
+        () => BrowserTestUtils.is_hidden(subtitlesPanel),
+        "Wait for panel to be hidden"
+      );
+
+      EventUtils.synthesizeKey("KEY_Escape", {}, pipWin);
+
+      info("Make sure subtitles settings panel closes after pressing ESC");
+      await panelHiddenPromise;
+
+      Assert.notEqual(
+        pipWin.document.activeElement,
+        subtitlesButton,
+        "Subtitles button does not have focus after closing panel"
+      );
+      Assert.ok(pipWin, "PiP window is still open");
+
+      clearSavedPosition();
+    }
+  );
+});
+
+/**
+ * Tests that pressing the Escape key will close the subtitles settings panel and
+ * refocus on the subtitles button if activated via the keyboard.
+ */
+add_task(async function test_closePanelESCKeyboardFocus() {
+  clearSavedPosition();
+
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE_WITH_WEBVTT,
+      gBrowser,
+    },
+    async browser => {
+      await SpecialPowers.pushPrefEnv({
+        set: [
+          [
+            "media.videocontrols.picture-in-picture.display-text-tracks.enabled",
+            true,
+          ],
+        ],
+      });
+
+      let videoID = "with-controls";
+
+      await ensureVideosReady(browser);
+      await prepareVideosAndWebVTTTracks(browser, videoID);
+      await SpecialPowers.spawn(browser, [videoID], async videoID => {
+        await content.document.getElementById(videoID).play();
+      });
+
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      // Resize PiP window so that subtitles button is visible
+      let resizePromise = BrowserTestUtils.waitForEvent(pipWin, "resize");
+      pipWin.resizeTo(640, 360);
+      await resizePromise;
+
+      let subtitlesButton = pipWin.document.getElementById("closed-caption");
+      Assert.ok(subtitlesButton, "Subtitles button found");
+
+      let subtitlesPanel = pipWin.document.getElementById("settings");
+      let subtitlesToggle = pipWin.document.getElementById("subtitles-toggle");
+      let panelVisiblePromise = BrowserTestUtils.waitForCondition(
+        () => BrowserTestUtils.is_visible(subtitlesPanel),
+        "Wait for panel to be visible"
+      );
+
+      subtitlesButton.focus();
+      EventUtils.synthesizeKey(" ", {}, pipWin);
+
+      await panelVisiblePromise;
+
+      Assert.equal(
+        pipWin.document.activeElement,
+        subtitlesToggle,
+        "Subtitles switch toggle should have focus after opening panel"
+      );
+
+      let panelHiddenPromise = BrowserTestUtils.waitForCondition(
+        () => BrowserTestUtils.is_hidden(subtitlesPanel),
+        "Wait for panel to be hidden"
+      );
+
+      EventUtils.synthesizeKey("KEY_Escape", {}, pipWin);
+
+      info("Make sure subtitles settings panel closes after pressing ESC");
+      await panelHiddenPromise;
+
+      Assert.equal(
+        pipWin.document.activeElement,
+        subtitlesButton,
+        "Subtitles button has focus after closing panel"
+      );
+      Assert.ok(pipWin, "PiP window is still open");
+
+      clearSavedPosition();
+    }
+  );
+});
+
+/**
+ * Tests keyboard navigation for the subtitles settings panel and that it closes after selecting
+ * the subtitles button.
+ */
+add_task(async function test_panelKeyboardButtons() {
+  clearSavedPosition();
+
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE_WITH_WEBVTT,
+      gBrowser,
+    },
+    async browser => {
+      await SpecialPowers.pushPrefEnv({
+        set: [
+          [
+            "media.videocontrols.picture-in-picture.display-text-tracks.enabled",
+            true,
+          ],
+        ],
+      });
+
+      let videoID = "with-controls";
+
+      await ensureVideosReady(browser);
+      await prepareVideosAndWebVTTTracks(browser, videoID);
+      await SpecialPowers.spawn(browser, [videoID], async videoID => {
+        await content.document.getElementById(videoID).play();
+        // Mute video
+        content.document.getElementById(videoID).muted = true;
+      });
+
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      // Resize PiP window so that subtitles button is visible
+      let resizePromise = BrowserTestUtils.waitForEvent(pipWin, "resize");
+      pipWin.resizeTo(640, 360);
+      await resizePromise;
+
+      let subtitlesButton = pipWin.document.getElementById("closed-caption");
+      Assert.ok(subtitlesButton, "Subtitles button found");
+
+      let subtitlesPanel = pipWin.document.getElementById("settings");
+      let subtitlesToggle = pipWin.document.getElementById("subtitles-toggle");
+      let panelVisiblePromise = BrowserTestUtils.waitForCondition(
+        () => BrowserTestUtils.is_visible(subtitlesPanel),
+        "Wait for panel to be visible"
+      );
+
+      subtitlesButton.focus();
+      EventUtils.synthesizeKey(" ", {}, pipWin);
+
+      await panelVisiblePromise;
+
+      Assert.equal(
+        pipWin.document.activeElement,
+        subtitlesToggle,
+        "Subtitles switch toggle should have focus after opening panel"
+      );
+
+      let fontMediumRadio = pipWin.document.getElementById("medium");
+      EventUtils.synthesizeKey("KEY_Tab", {}, pipWin);
+
+      Assert.equal(
+        pipWin.document.activeElement,
+        fontMediumRadio,
+        "Medium font size radio button should have focus"
+      );
+
+      let fontSmallRadio = pipWin.document.getElementById("small");
+      EventUtils.synthesizeKey("KEY_ArrowUp", {}, pipWin);
+
+      Assert.equal(
+        pipWin.document.activeElement,
+        fontSmallRadio,
+        "Small font size radio button should have focus"
+      );
+      Assert.ok(isVideoMuted(browser, videoID), "Video should still be muted");
+      Assert.equal(
+        SpecialPowers.getCharPref(
+          "media.videocontrols.picture-in-picture.display-text-tracks.size"
+        ),
+        "small",
+        "Font size changed to small"
+      );
+
+      subtitlesButton.focus();
+
+      let panelHiddenPromise = BrowserTestUtils.waitForCondition(
+        () => BrowserTestUtils.is_hidden(subtitlesPanel),
+        "Wait for panel to be hidden"
+      );
+
+      EventUtils.synthesizeKey(" ", {}, pipWin);
+
+      info(
+        "Make sure subtitles settings panel closes after pressing the subtitles button"
+      );
+      await panelHiddenPromise;
+
+      Assert.ok(pipWin, "PiP window is still open");
+
+      clearSavedPosition();
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_tabIconOverlayPiP.js b/toolkit/components/pictureinpicture/tests/browser_tabIconOverlayPiP.js
new file mode 100644
index 0000000000..3ca55f2c73
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_tabIconOverlayPiP.js
@@ -0,0 +1,90 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * The goal of this test is check the that "tab-icon-overlay" image is
+ * showing when the tab is using PiP.
+ *
+ * The browser will create a tab and open a video using PiP
+ * then the tests check that the tab icon overlay image is showing*
+ *
+ *
+ */
+add_task(async () => {
+  let videoID = "with-controls";
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE_WITH_SOUND,
+      gBrowser,
+    },
+    async browser => {
+      await ensureVideosReady(browser);
+
+      let audioPromise = BrowserTestUtils.waitForEvent(
+        browser,
+        "DOMAudioPlaybackStarted"
+      );
+
+      await SpecialPowers.spawn(browser, [videoID], async videoID => {
+        await content.document.getElementById(videoID).play();
+      });
+
+      // Check that video is playing
+      ok(!(await isVideoPaused(browser, videoID)), "The video is not paused.");
+      await audioPromise;
+
+      // Need tab to access the tab-icon-overlay element
+      let tab = gBrowser.getTabForBrowser(browser);
+
+      // Use tab to get the tab-icon-overlay element
+      let tabIconOverlay = tab.getElementsByClassName("tab-icon-overlay")[0];
+
+      // Not in PiP yet so the tab-icon-overlay does not have "pictureinpicture" attribute
+      ok(!tabIconOverlay.hasAttribute("pictureinpicture"), "Not using PiP");
+
+      // Sound is playing so tab should have "soundplaying" attribute
+      ok(tabIconOverlay.hasAttribute("soundplaying"), "Sound is playing");
+
+      // Start the PiP
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      // Check that video is still playing
+      ok(!(await isVideoPaused(browser, videoID)), "The video is not paused.");
+
+      // Video is still playing so the tab-icon-overlay should have "soundplaying" as an attribute
+      ok(
+        tabIconOverlay.hasAttribute("soundplaying"),
+        "Tab knows sound is playing"
+      );
+
+      // Now in PiP. "pictureinpicture" is an attribute
+      ok(
+        tabIconOverlay.hasAttribute("pictureinpicture"),
+        "Tab knows were using PiP"
+      );
+
+      // We know the tab has sound playing and it is using PiP so we can check the
+      // tab-icon-overlay image is showing
+      let style = window.getComputedStyle(tabIconOverlay);
+      Assert.equal(
+        style.listStyleImage,
+        'url("chrome://browser/skin/tabbrowser/tab-audio-playing-small.svg")',
+        "Got the tab-icon-overlay image"
+      );
+
+      // Check tab is not muted
+      ok(!tabIconOverlay.hasAttribute("muted"), "Tab is not muted");
+
+      // Click on tab icon overlay to mute tab and check it is muted
+      tabIconOverlay.click();
+      ok(tabIconOverlay.hasAttribute("muted"), "Tab is muted");
+
+      // Click on tab icon overlay to unmute tab and check it is not muted
+      tabIconOverlay.click();
+      ok(!tabIconOverlay.hasAttribute("muted"), "Tab is not muted");
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_telemetry_enhancements.js b/toolkit/components/pictureinpicture/tests/browser_telemetry_enhancements.js
new file mode 100644
index 0000000000..3f027de170
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_telemetry_enhancements.js
@@ -0,0 +1,230 @@
+/* Any copyright is dedicated to the Public Domain.
+  http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const TEST_PAGE_LONG = TEST_ROOT + "test-video-selection.html";
+
+const { TelemetryTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/TelemetryTestUtils.sys.mjs"
+);
+
+const EXPECTED_EVENT_CREATE = [
+  [
+    "pictureinpicture",
+    "create",
+    "player",
+    undefined,
+    { ccEnabled: "false", webVTTSubtitles: "false" },
+  ],
+];
+
+const EXPECTED_EVENT_CREATE_WITH_TEXT_TRACKS = [
+  [
+    "pictureinpicture",
+    "create",
+    "player",
+    undefined,
+    { ccEnabled: "true", webVTTSubtitles: "true" },
+  ],
+];
+
+const EXPECTED_EVENT_CLOSED_METHOD_CLOSE_BUTTON = [
+  {
+    category: "pictureinpicture",
+    method: "closed_method",
+    object: "closeButton",
+  },
+];
+
+const videoID = "with-controls";
+
+const EXPECTED_EVENT_CLOSED_METHOD_UNPIP = [
+  {
+    category: "pictureinpicture",
+    method: "closed_method",
+    object: "unpip",
+  },
+];
+
+const FULLSCREEN_EVENTS = [
+  {
+    category: "pictureinpicture",
+    method: "fullscreen",
+    object: "player",
+    extraKey: { enter: "true" },
+  },
+  {
+    category: "pictureinpicture",
+    method: "fullscreen",
+    object: "player",
+    extraKey: { enter: "true" },
+  },
+];
+
+add_task(async function testCreateAndCloseButtonTelemetry() {
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: TEST_PAGE,
+    },
+    async browser => {
+      Services.telemetry.clearEvents();
+
+      await ensureVideosReady(browser);
+
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      let filter = {
+        category: "pictureinpicture",
+        method: "create",
+        object: "player",
+      };
+      await waitForTelemeryEvents(
+        filter,
+        EXPECTED_EVENT_CREATE.length,
+        "parent"
+      );
+
+      TelemetryTestUtils.assertEvents(EXPECTED_EVENT_CREATE, filter, {
+        clear: true,
+        process: "parent",
+      });
+
+      let pipClosed = BrowserTestUtils.domWindowClosed(pipWin);
+      let closeButton = pipWin.document.getElementById("close");
+      EventUtils.synthesizeMouseAtCenter(closeButton, {}, pipWin);
+      await pipClosed;
+
+      filter = {
+        category: "pictureinpicture",
+        method: "closed_method",
+        object: "closeButton",
+      };
+      await waitForTelemeryEvents(
+        filter,
+        EXPECTED_EVENT_CLOSED_METHOD_CLOSE_BUTTON.length,
+        "parent"
+      );
+
+      TelemetryTestUtils.assertEvents(
+        EXPECTED_EVENT_CLOSED_METHOD_CLOSE_BUTTON,
+        filter,
+        { clear: true, process: "parent" }
+      );
+
+      let hist = TelemetryTestUtils.getAndClearHistogram(
+        "FX_PICTURE_IN_PICTURE_WINDOW_OPEN_DURATION"
+      );
+
+      Assert.ok(hist, "Histogram exists");
+    }
+  );
+});
+
+add_task(async function textTextTracksAndUnpipTelemetry() {
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      [
+        "media.videocontrols.picture-in-picture.display-text-tracks.enabled",
+        true,
+      ],
+    ],
+  });
+
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE_WITH_WEBVTT,
+      gBrowser,
+    },
+    async browser => {
+      Services.telemetry.clearEvents();
+
+      await ensureVideosReady(browser);
+
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      let filter = {
+        category: "pictureinpicture",
+        method: "create",
+        object: "player",
+      };
+      await waitForTelemeryEvents(
+        filter,
+        EXPECTED_EVENT_CREATE_WITH_TEXT_TRACKS.length,
+        "parent"
+      );
+
+      TelemetryTestUtils.assertEvents(
+        EXPECTED_EVENT_CREATE_WITH_TEXT_TRACKS,
+        filter,
+        { clear: true, process: "parent" }
+      );
+
+      let pipClosed = BrowserTestUtils.domWindowClosed(pipWin);
+      let unpipButton = pipWin.document.getElementById("unpip");
+      EventUtils.synthesizeMouseAtCenter(unpipButton, {}, pipWin);
+      await pipClosed;
+
+      filter = {
+        category: "pictureinpicture",
+        method: "closed_method",
+        object: "unpip",
+      };
+      await waitForTelemeryEvents(
+        filter,
+        EXPECTED_EVENT_CLOSED_METHOD_UNPIP.length,
+        "parent"
+      );
+
+      TelemetryTestUtils.assertEvents(
+        EXPECTED_EVENT_CLOSED_METHOD_UNPIP,
+        filter,
+        { clear: true, process: "parent" }
+      );
+    }
+  );
+});
+
+add_task(async function test_fullscreen_events() {
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE,
+      gBrowser,
+    },
+    async browser => {
+      Services.telemetry.clearEvents();
+
+      await ensureVideosReady(browser);
+
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      let fullscreenBtn = pipWin.document.getElementById("fullscreen");
+
+      await promiseFullscreenEntered(pipWin, () => {
+        fullscreenBtn.click();
+      });
+
+      await promiseFullscreenExited(pipWin, () => {
+        fullscreenBtn.click();
+      });
+
+      let filter = {
+        category: "pictureinpicture",
+        method: "fullscreen",
+        object: "player",
+      };
+      await waitForTelemeryEvents(filter, FULLSCREEN_EVENTS.length, "parent");
+
+      TelemetryTestUtils.assertEvents(FULLSCREEN_EVENTS, filter, {
+        clear: true,
+        process: "parent",
+      });
+
+      await ensureMessageAndClosePiP(browser, videoID, pipWin, false);
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_text_tracks_webvtt_1.js b/toolkit/components/pictureinpicture/tests/browser_text_tracks_webvtt_1.js
new file mode 100644
index 0000000000..b2b1ded13d
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_text_tracks_webvtt_1.js
@@ -0,0 +1,129 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * This test ensures that text tracks shown on the source video
+ * do not appear on a newly created pip window if the pref
+ * is disabled.
+ */
+add_task(async function test_text_tracks_new_window_pref_disabled() {
+  info("Running test: new window - pref disabled");
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      [
+        "media.videocontrols.picture-in-picture.display-text-tracks.enabled",
+        false,
+      ],
+    ],
+  });
+  let videoID = "with-controls";
+
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE_WITH_WEBVTT,
+      gBrowser,
+    },
+    async browser => {
+      await prepareVideosAndWebVTTTracks(browser, videoID);
+
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+      let pipBrowser = pipWin.document.getElementById("browser");
+
+      await SpecialPowers.spawn(pipBrowser, [], async () => {
+        info("Checking text track content in pip window");
+        let textTracks = content.document.getElementById("texttracks");
+
+        ok(textTracks, "TextTracks container should exist in the pip window");
+        ok(
+          !textTracks.textContent,
+          "Text tracks should not be visible on the pip window"
+        );
+      });
+    }
+  );
+});
+
+/**
+ * This test ensures that text tracks shown on the source video
+ * appear on a newly created pip window if the pref is enabled.
+ */
+add_task(async function test_text_tracks_new_window_pref_enabled() {
+  info("Running test: new window - pref enabled");
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      [
+        "media.videocontrols.picture-in-picture.display-text-tracks.enabled",
+        true,
+      ],
+    ],
+  });
+  let videoID = "with-controls";
+
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE_WITH_WEBVTT,
+      gBrowser,
+    },
+    async browser => {
+      await prepareVideosAndWebVTTTracks(browser, videoID);
+
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+      let pipBrowser = pipWin.document.getElementById("browser");
+
+      await SpecialPowers.spawn(pipBrowser, [], async () => {
+        info("Checking text track content in pip window");
+        let textTracks = content.document.getElementById("texttracks");
+        ok(textTracks, "TextTracks container should exist in the pip window");
+        await ContentTaskUtils.waitForCondition(() => {
+          return textTracks.textContent;
+        }, `Text track is still not visible on the pip window. Got ${textTracks.textContent}`);
+      });
+    }
+  );
+});
+
+/**
+ * This test ensures that text tracks do not appear on a new pip window
+ * if no track is loaded and the pref is enabled.
+ */
+add_task(async function test_text_tracks_new_window_no_track() {
+  info("Running test: new window - no track");
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      [
+        "media.videocontrols.picture-in-picture.display-text-tracks.enabled",
+        true,
+      ],
+    ],
+  });
+  let videoID = "with-controls";
+
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE_WITH_WEBVTT,
+      gBrowser,
+    },
+    async browser => {
+      await prepareVideosAndWebVTTTracks(browser, videoID, -1);
+
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+      let pipBrowser = pipWin.document.getElementById("browser");
+
+      await SpecialPowers.spawn(pipBrowser, [], async () => {
+        info("Checking text track content in pip window");
+        let textTracks = content.document.getElementById("texttracks");
+
+        ok(textTracks, "TextTracks container should exist in the pip window");
+        ok(
+          !textTracks.textContent,
+          "Text tracks should not be visible on the pip window"
+        );
+      });
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_text_tracks_webvtt_2.js b/toolkit/components/pictureinpicture/tests/browser_text_tracks_webvtt_2.js
new file mode 100644
index 0000000000..2a6114baab
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_text_tracks_webvtt_2.js
@@ -0,0 +1,444 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * This test ensures that text tracks disappear from the pip window
+ * when the pref is disabled.
+ */
+add_task(async function test_text_tracks_existing_window_pref_disabled() {
+  info("Running test: existing window - pref disabled");
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      [
+        "media.videocontrols.picture-in-picture.display-text-tracks.enabled",
+        true,
+      ],
+    ],
+  });
+  let videoID = "with-controls";
+
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE_WITH_WEBVTT,
+      gBrowser,
+    },
+    async browser => {
+      await prepareVideosAndWebVTTTracks(browser, videoID);
+
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+      let pipBrowser = pipWin.document.getElementById("browser");
+
+      await SpecialPowers.spawn(pipBrowser, [], async () => {
+        info("Checking text track content in pip window");
+        let textTracks = content.document.getElementById("texttracks");
+        ok(textTracks, "TextTracks container should exist in the pip window");
+        await ContentTaskUtils.waitForCondition(() => {
+          return textTracks.textContent;
+        }, `Text track is still not visible on the pip window. Got ${textTracks.textContent}`);
+      });
+
+      info("Turning off pref");
+      await SpecialPowers.popPrefEnv();
+      await SpecialPowers.pushPrefEnv({
+        set: [
+          [
+            "media.videocontrols.picture-in-picture.display-text-tracks.enabled",
+            false,
+          ],
+        ],
+      });
+
+      // Verify that cue is no longer on the pip window
+      info("Checking that cue is no longer on pip window");
+      await SpecialPowers.spawn(pipBrowser, [], async () => {
+        let textTracks = content.document.getElementById("texttracks");
+        await ContentTaskUtils.waitForCondition(() => {
+          return !textTracks.textContent;
+        }, `Text track is still visible on the pip window. Got ${textTracks.textContent}`);
+        info("Successfully removed text tracks from pip window");
+      });
+    }
+  );
+});
+
+/**
+ * This test ensures that text tracks shown on the source video
+ * window appear on an existing pip window when the pref is enabled.
+ */
+add_task(async function test_text_tracks_existing_window_pref_enabled() {
+  info("Running test: existing window - pref enabled");
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      [
+        "media.videocontrols.picture-in-picture.display-text-tracks.enabled",
+        false,
+      ],
+    ],
+  });
+  let videoID = "with-controls";
+
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE_WITH_WEBVTT,
+      gBrowser,
+    },
+    async browser => {
+      await prepareVideosAndWebVTTTracks(browser, videoID);
+
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+      let pipBrowser = pipWin.document.getElementById("browser");
+
+      await SpecialPowers.spawn(pipBrowser, [], async () => {
+        info("Checking text track content in pip window");
+        let textTracks = content.document.getElementById("texttracks");
+
+        ok(textTracks, "TextTracks container should exist in the pip window");
+        ok(
+          !textTracks.textContent,
+          "Text tracks should not be visible on the pip window"
+        );
+      });
+
+      info("Turning on pref");
+      await SpecialPowers.popPrefEnv();
+      await SpecialPowers.pushPrefEnv({
+        set: [
+          [
+            "media.videocontrols.picture-in-picture.display-text-tracks.enabled",
+            true,
+          ],
+        ],
+      });
+
+      info("Checking that cue is on pip window");
+      await SpecialPowers.spawn(pipBrowser, [], async () => {
+        let textTracks = content.document.getElementById("texttracks");
+        await ContentTaskUtils.waitForCondition(() => {
+          return textTracks.textContent;
+        }, `Text track is still not visible on the pip window. Got ${textTracks.textContent}`);
+        info("Successfully displayed text tracks on pip window");
+      });
+    }
+  );
+});
+
+/**
+ * This test ensures that text tracks update to the correct track
+ * when a new track is selected.
+ */
+add_task(async function test_text_tracks_existing_window_new_track() {
+  info("Running test: existing window - new track");
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      [
+        "media.videocontrols.picture-in-picture.display-text-tracks.enabled",
+        true,
+      ],
+    ],
+  });
+  let videoID = "with-controls";
+
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE_WITH_WEBVTT,
+      gBrowser,
+    },
+    async browser => {
+      await prepareVideosAndWebVTTTracks(browser, videoID);
+
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+      let pipBrowser = pipWin.document.getElementById("browser");
+
+      await SpecialPowers.spawn(pipBrowser, [], async () => {
+        info("Checking text track content in pip window");
+        let textTracks = content.document.getElementById("texttracks");
+        ok(textTracks, "TextTracks container should exist in the pip window");
+        await ContentTaskUtils.waitForCondition(() => {
+          return textTracks.textContent;
+        }, `Text track is still not visible on the pip window. Got ${textTracks.textContent}`);
+        ok(
+          textTracks.textContent.includes("track 1"),
+          "Track 1 should be loaded"
+        );
+      });
+
+      // Change track in the content window
+      await SpecialPowers.spawn(browser, [videoID], async videoID => {
+        let video = content.document.getElementById(videoID);
+        let tracks = video.textTracks;
+
+        info("Changing to a new track");
+        let track1 = tracks[0];
+        track1.mode = "disabled";
+        let track2 = tracks[1];
+        track2.mode = "showing";
+      });
+
+      // Ensure new track is loaded
+      await SpecialPowers.spawn(pipBrowser, [], async () => {
+        info("Checking new text track content in pip window");
+        let textTracks = content.document.getElementById("texttracks");
+
+        await ContentTaskUtils.waitForCondition(() => {
+          return textTracks.textContent;
+        }, `Text track is still not visible on the pip window. Got ${textTracks.textContent}`);
+        ok(
+          textTracks.textContent.includes("track 2"),
+          "Track 2 should be loaded"
+        );
+      });
+    }
+  );
+});
+
+/**
+ * This test ensures that text tracks are correctly updated.
+ */
+add_task(async function test_text_tracks_existing_window_cues() {
+  info("Running test: existing window - cues");
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      [
+        "media.videocontrols.picture-in-picture.display-text-tracks.enabled",
+        true,
+      ],
+    ],
+  });
+  let videoID = "with-controls";
+
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE_WITH_WEBVTT,
+      gBrowser,
+    },
+    async browser => {
+      await prepareVideosAndWebVTTTracks(browser, videoID);
+
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+      let pipBrowser = pipWin.document.getElementById("browser");
+
+      await SpecialPowers.spawn(pipBrowser, [], async () => {
+        let textTracks = content.document.getElementById("texttracks");
+        ok(textTracks, "TextTracks container should exist in the pip window");
+
+        // Verify that first cue appears
+        info("Checking first cue on pip window");
+        await ContentTaskUtils.waitForCondition(() => {
+          return textTracks.textContent;
+        }, `Text track is still not visible on the pip window. Got ${textTracks.textContent}`);
+        ok(
+          textTracks.textContent.includes("cue 1"),
+          `Expected text should be displayed on the pip window. Got ${textTracks.textContent}.`
+        );
+      });
+
+      // Play video to move to the next cue
+      await waitForNextCue(browser, videoID);
+
+      // Test remaining cues
+      await SpecialPowers.spawn(pipBrowser, [], async () => {
+        let textTracks = content.document.getElementById("texttracks");
+
+        // Verify that empty cue makes text disappear
+        info("Checking empty cue in pip window");
+        await ContentTaskUtils.waitForCondition(() => {
+          info(`Current text content is: ${textTracks.textContent}`);
+          return !textTracks.textContent;
+        }, `Text track is still visible on the pip window. Got ${textTracks.textContent}`);
+      });
+
+      await waitForNextCue(browser, videoID);
+
+      // Wait and verify second cue
+      await SpecialPowers.spawn(pipBrowser, [], async () => {
+        let textTracks = content.document.getElementById("texttracks");
+        info("Checking second cue in pip window");
+        await ContentTaskUtils.waitForCondition(() => {
+          // Cue may not appear right away after cuechange event.
+          // Wait until it appears before verifying text content.
+          info(`Current text content is: ${textTracks.textContent}`);
+          return (
+            textTracks.textContent && textTracks.textContent.includes("cue 2")
+          );
+        }, `Text track is still not visible on the pip window. Got ${textTracks.textContent}`);
+      });
+    }
+  );
+});
+
+/**
+ * This test ensures that text tracks disappear if no track is selected.
+ */
+add_task(async function test_text_tracks_existing_window_no_track() {
+  info("Running test: existing window - no track");
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      [
+        "media.videocontrols.picture-in-picture.display-text-tracks.enabled",
+        true,
+      ],
+    ],
+  });
+  let videoID = "with-controls";
+
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE_WITH_WEBVTT,
+      gBrowser,
+    },
+    async browser => {
+      await prepareVideosAndWebVTTTracks(browser, videoID);
+
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+      let pipBrowser = pipWin.document.getElementById("browser");
+
+      await SpecialPowers.spawn(pipBrowser, [], async () => {
+        info("Checking text track content in pip window");
+        let textTracks = content.document.getElementById("texttracks");
+        ok(textTracks, "TextTracks container should exist in the pip window");
+        await ContentTaskUtils.waitForCondition(() => {
+          return textTracks.textContent;
+        }, `Text track is still not visible on the pip window. Got ${textTracks.textContent}`);
+      });
+
+      // Remove track in the content window
+      await SpecialPowers.spawn(browser, [videoID], async videoID => {
+        let video = content.document.getElementById(videoID);
+        let tracks = video.textTracks;
+
+        info("Removing tracks");
+        let track1 = tracks[0];
+        track1.mode = "disabled";
+        let track2 = tracks[1];
+        track2.mode = "disabled";
+      });
+
+      await SpecialPowers.spawn(pipBrowser, [], async () => {
+        info("Checking that text track disappears from pip window");
+        let textTracks = content.document.getElementById("texttracks");
+
+        await ContentTaskUtils.waitForCondition(() => {
+          return !textTracks.textContent;
+        }, `Text track is still visible on the pip window. Got ${textTracks.textContent}`);
+      });
+    }
+  );
+});
+
+/**
+ * This test ensures that text tracks appear correctly if there are multiple active cues.
+ */
+add_task(async function test_text_tracks_existing_window_multi_cue() {
+  info("Running test: existing window - multi cue");
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      [
+        "media.videocontrols.picture-in-picture.display-text-tracks.enabled",
+        true,
+      ],
+    ],
+  });
+  let videoID = "with-controls";
+
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE_WITH_WEBVTT,
+      gBrowser,
+    },
+    async browser => {
+      await prepareVideosAndWebVTTTracks(browser, videoID, 2);
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+      let pipBrowser = pipWin.document.getElementById("browser");
+
+      await SpecialPowers.spawn(pipBrowser, [], async () => {
+        info("Checking text track content in pip window");
+        let textTracks = content.document.getElementById("texttracks");
+
+        // Verify multiple active cues
+        ok(textTracks, "TextTracks container should exist in the pip window");
+        await ContentTaskUtils.waitForCondition(() => {
+          return textTracks.textContent;
+        }, `Text track is still not visible on the pip window. Got ${textTracks.textContent}`);
+        is(textTracks.children.length, 2, "Text tracks should load 2 cues");
+      });
+    }
+  );
+});
+
+/**
+ * This test ensures that the showHiddenTextTracks override correctly shows
+ * text tracks with a mode of "hidden".
+ */
+const prepareHiddenTrackTest = () =>
+  new Promise((resolve, reject) => {
+    BrowserTestUtils.withNewTab(
+      {
+        url: TEST_PAGE_WITH_WEBVTT,
+        gBrowser,
+      },
+
+      async browser => {
+        const videoID = "with-controls";
+        await prepareVideosAndWebVTTTracks(browser, videoID, 0, "hidden");
+        await SpecialPowers.spawn(browser, [{ videoID }], async args => {
+          let video = content.document.getElementById(args.videoID);
+          const tracks = video.textTracks;
+          ok(tracks[0].mode === "hidden", "Track 1 mode is 'hidden'");
+        });
+
+        let pipWin = await triggerPictureInPicture(browser, videoID);
+        ok(pipWin, "Got Picture-in-Picture window.");
+        let pipBrowser = pipWin.document.getElementById("browser");
+        if (!pipBrowser) {
+          reject();
+        }
+        resolve(pipBrowser);
+      }
+    );
+  });
+
+add_task(async function test_hidden_text_tracks_override() {
+  info("Running test - showHiddenTextTracks");
+
+  info("hidden mode with override");
+  Services.ppmm.sharedData.set(SHARED_DATA_KEY, {
+    "*://example.com/*": { showHiddenTextTracks: true },
+  });
+  Services.ppmm.sharedData.flush();
+
+  await prepareHiddenTrackTest().then(async pipBrowser => {
+    await SpecialPowers.spawn(pipBrowser, [], async () => {
+      info("Checking text track content in pip window");
+      let textTracks = content.document.getElementById("texttracks");
+
+      // Verify text track is showing in PiP window.
+      ok(textTracks, "TextTracks container should exist in the pip window");
+      ok(textTracks.textContent.includes("track 1"), "Track 1 should be shown");
+    });
+  });
+
+  info("hidden mode without override");
+  Services.ppmm.sharedData.set(SHARED_DATA_KEY, {});
+  Services.ppmm.sharedData.flush();
+
+  await prepareHiddenTrackTest().then(async pipBrowser => {
+    await SpecialPowers.spawn(pipBrowser, [], async () => {
+      info("Checking text track content in pip window");
+      let textTracks = content.document.getElementById("texttracks");
+
+      // Verify text track is [not] showing in PiP window.
+      ok(
+        !textTracks || !textTracks.textContent.length,
+        "Text track should NOT appear in PiP window."
+      );
+    });
+  });
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_text_tracks_webvtt_3.js b/toolkit/components/pictureinpicture/tests/browser_text_tracks_webvtt_3.js
new file mode 100644
index 0000000000..3e62556d45
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_text_tracks_webvtt_3.js
@@ -0,0 +1,218 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Verifies the value of a cue's .line property.
+ * @param {Element} browser The <xul:browser> hosting the <video>
+ * @param {String} videoID The ID of the video being checked
+ * @param {Integer} trackIndex The index of the track to be loaded
+ * @param {Integer} cueIndex The index of the cue to be tested on
+ * @param {Integer|String} expectedValue The expected line value of the cue
+ */
+async function verifyLineForCue(
+  browser,
+  videoID,
+  trackIndex,
+  cueIndex,
+  expectedValue
+) {
+  await SpecialPowers.spawn(
+    browser,
+    [{ videoID, trackIndex, cueIndex, expectedValue }],
+    async args => {
+      info("Checking .line property values");
+      const video = content.document.getElementById(args.videoID);
+      const activeCues = video.textTracks[args.trackIndex].activeCues;
+      const vttCueLine = activeCues[args.cueIndex].line;
+      is(vttCueLine, args.expectedValue, "Cue line should have expected value");
+    }
+  );
+}
+
+/**
+ * This test ensures that text tracks appear in expected order if
+ * VTTCue.line property is auto.
+ */
+add_task(async function test_text_tracks_new_window_line_auto() {
+  info("Running test: new window - line auto");
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      [
+        "media.videocontrols.picture-in-picture.display-text-tracks.enabled",
+        true,
+      ],
+    ],
+  });
+  let videoID = "with-controls";
+
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE_WITH_WEBVTT,
+      gBrowser,
+    },
+    async browser => {
+      let trackIndex = 2;
+      await prepareVideosAndWebVTTTracks(browser, videoID, trackIndex);
+
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+      let pipBrowser = pipWin.document.getElementById("browser");
+
+      await verifyLineForCue(browser, videoID, trackIndex, 0, "auto");
+      await verifyLineForCue(browser, videoID, trackIndex, 1, "auto");
+
+      await SpecialPowers.spawn(pipBrowser, [], async () => {
+        info("Checking text track content in pip window");
+        let textTracks = content.document.getElementById("texttracks");
+        ok(textTracks, "TextTracks container should exist in the pip window");
+        await ContentTaskUtils.waitForCondition(() => {
+          return textTracks.textContent;
+        }, `Text track is still not visible on the pip window. Got ${textTracks.textContent}`);
+
+        let cueDivs = textTracks.children;
+
+        is(cueDivs.length, 2, "There should be 2 active cues");
+        // cue1 in this case refers to the first cue to be defined in the vtt file.
+        // cue2 is therefore the next cue to be defined right after in the vtt file.
+        ok(
+          cueDivs[0].textContent.includes("cue 2"),
+          `cue 2 should be above. Got: ${cueDivs[0].textContent}`
+        );
+        ok(
+          cueDivs[1].textContent.includes("cue 1"),
+          `cue 1 should be below. Got: ${cueDivs[1].textContent}`
+        );
+      });
+    }
+  );
+});
+
+/**
+ * This test ensures that text tracks appear in expected order if
+ * VTTCue.line property is an integer.
+ */
+add_task(async function test_text_tracks_new_window_line_integer() {
+  info("Running test: new window - line integer");
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      [
+        "media.videocontrols.picture-in-picture.display-text-tracks.enabled",
+        true,
+      ],
+    ],
+  });
+  let videoID = "with-controls";
+
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE_WITH_WEBVTT,
+      gBrowser,
+    },
+    async browser => {
+      let trackIndex = 3;
+      await prepareVideosAndWebVTTTracks(browser, videoID, trackIndex);
+
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+      let pipBrowser = pipWin.document.getElementById("browser");
+
+      await verifyLineForCue(browser, videoID, trackIndex, 0, 2);
+      await verifyLineForCue(browser, videoID, trackIndex, 1, 3);
+      await verifyLineForCue(browser, videoID, trackIndex, 2, 1);
+
+      await SpecialPowers.spawn(pipBrowser, [], async () => {
+        info("Checking text track content in pip window");
+        let textTracks = content.document.getElementById("texttracks");
+        ok(textTracks, "TextTracks container should exist in the pip window");
+        await ContentTaskUtils.waitForCondition(() => {
+          return textTracks.textContent;
+        }, `Text track is still not visible on the pip window. Got ${textTracks.textContent}`);
+
+        let cueDivs = textTracks.children;
+
+        is(cueDivs.length, 3, "There should be 3 active cues");
+
+        // cue1 in this case refers to the first cue to be defined in the vtt file.
+        // cue2 is therefore the next cue to be defined right after in the vtt file.
+        ok(
+          cueDivs[0].textContent.includes("cue 3"),
+          `cue 3 should be above. Got: ${cueDivs[0].textContent}`
+        );
+        ok(
+          cueDivs[1].textContent.includes("cue 1"),
+          `cue 1 should be next. Got: ${cueDivs[1].textContent}`
+        );
+        ok(
+          cueDivs[2].textContent.includes("cue 2"),
+          `cue 2 should be below. Got: ${cueDivs[2].textContent}`
+        );
+      });
+    }
+  );
+});
+
+/**
+ * This test ensures that text tracks appear in expected order if
+ * VTTCue.line property is a percentage value.
+ */
+add_task(async function test_text_tracks_new_window_line_percent() {
+  info("Running test: new window - line percent");
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      [
+        "media.videocontrols.picture-in-picture.display-text-tracks.enabled",
+        true,
+      ],
+    ],
+  });
+  let videoID = "with-controls";
+
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE_WITH_WEBVTT,
+      gBrowser,
+    },
+    async browser => {
+      let trackIndex = 4;
+      await prepareVideosAndWebVTTTracks(browser, videoID, trackIndex);
+
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+      let pipBrowser = pipWin.document.getElementById("browser");
+
+      await verifyLineForCue(browser, videoID, trackIndex, 0, 90);
+      await verifyLineForCue(browser, videoID, trackIndex, 1, 10);
+      await verifyLineForCue(browser, videoID, trackIndex, 2, 50);
+
+      await SpecialPowers.spawn(pipBrowser, [], async () => {
+        info("Checking text track content in pip window");
+        let textTracks = content.document.getElementById("texttracks");
+        ok(textTracks, "TextTracks container should exist in the pip window");
+
+        await ContentTaskUtils.waitForCondition(() => {
+          return textTracks.textContent;
+        }, `Text track is still not visible on the pip window. Got ${textTracks.textContent}`);
+
+        let cueDivs = textTracks.children;
+        is(cueDivs.length, 3, "There should be 3 active cues");
+
+        // cue1 in this case refers to the first cue to be defined in the vtt file.
+        // cue2 is therefore the next cue to be defined right after in the vtt file.
+        ok(
+          cueDivs[0].textContent.includes("cue 2"),
+          `cue 2 should be above. Got: ${cueDivs[0].textContent}`
+        );
+        ok(
+          cueDivs[1].textContent.includes("cue 3"),
+          `cue 3 should be next. Got: ${cueDivs[1].textContent}`
+        );
+        ok(
+          cueDivs[2].textContent.includes("cue 1"),
+          `cue 1 should be below. Got: ${cueDivs[2].textContent}`
+        );
+      });
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_thirdPartyIframe.js b/toolkit/components/pictureinpicture/tests/browser_thirdPartyIframe.js
new file mode 100644
index 0000000000..e02fe21f4e
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_thirdPartyIframe.js
@@ -0,0 +1,72 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const EXAMPLE_COM = getRootDirectory(gTestPath).replace(
+  "chrome://mochitests/content",
+  "https://example.com"
+);
+const EXAMPLE_ORG = getRootDirectory(gTestPath).replace(
+  "chrome://mochitests/content",
+  "https://example.org"
+);
+const EXAMPLE_COM_TEST_PAGE = EXAMPLE_COM + "test-page.html";
+const EXAMPLE_ORG_WITH_IFRAME = EXAMPLE_ORG + "test-page-with-iframe.html";
+
+/**
+ * Tests that videos hosted inside of a third-party <iframe> can be opened
+ * in a Picture-in-Picture window.
+ */
+add_task(async () => {
+  for (let videoID of ["with-controls", "no-controls"]) {
+    info(`Testing ${videoID} case.`);
+
+    await BrowserTestUtils.withNewTab(
+      {
+        url: EXAMPLE_ORG_WITH_IFRAME,
+        gBrowser,
+      },
+      async browser => {
+        // EXAMPLE_ORG_WITH_IFRAME is hosted at a different domain from
+        // EXAMPLE_COM_TEST_PAGE, so loading EXAMPLE_COM_TEST_PAGE within
+        // the iframe will act as our third-party iframe.
+        await SpecialPowers.spawn(
+          browser,
+          [EXAMPLE_COM_TEST_PAGE],
+          async EXAMPLE_COM_TEST_PAGE => {
+            let iframe = content.document.getElementById("iframe");
+            let loadPromise = ContentTaskUtils.waitForEvent(iframe, "load");
+            iframe.src = EXAMPLE_COM_TEST_PAGE;
+            await loadPromise;
+          }
+        );
+
+        let iframeBc = browser.browsingContext.children[0];
+
+        if (gFissionBrowser) {
+          Assert.notEqual(
+            browser.browsingContext.currentWindowGlobal.osPid,
+            iframeBc.currentWindowGlobal.osPid,
+            "The iframe should be running in a different process."
+          );
+        }
+
+        let pipWin = await triggerPictureInPicture(iframeBc, videoID);
+        ok(pipWin, "Got Picture-in-Picture window.");
+
+        await ensureMessageAndClosePiP(iframeBc, videoID, pipWin, true);
+
+        await SimpleTest.promiseFocus(window);
+
+        // Now try using the command / keyboard shortcut
+        pipWin = await triggerPictureInPicture(iframeBc, videoID, () => {
+          document.getElementById("View:PictureInPicture").doCommand();
+        });
+        ok(pipWin, "Got Picture-in-Picture window using command.");
+
+        await ensureMessageAndClosePiP(iframeBc, videoID, pipWin, true);
+      }
+    );
+  }
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_toggleAfterTabTearOutIn.js b/toolkit/components/pictureinpicture/tests/browser_toggleAfterTabTearOutIn.js
new file mode 100644
index 0000000000..5588b3a775
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_toggleAfterTabTearOutIn.js
@@ -0,0 +1,58 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Helper function that tries to use the mouse to open the Picture-in-Picture
+ * player window for a video with and without the built-in controls.
+ *
+ * @param {Element} tab The tab to be tested.
+ * @return Promise
+ * @resolves When the toggles for both the video-with-controls and
+ * video-without-controls have been tested.
+ */
+async function testToggleForTab(tab) {
+  for (let videoID of ["with-controls", "no-controls"]) {
+    let browser = tab.linkedBrowser;
+    info(`Testing ${videoID} case.`);
+
+    await testToggleHelper(browser, videoID, true);
+  }
+}
+
+/**
+ * Tests that the Picture-in-Picture toggle still works after tearing out the
+ * tab into a new window, or tearing in a tab from one window to another.
+ */
+add_task(async () => {
+  // The startingTab will be torn out and placed in the new window.
+  let startingTab = await BrowserTestUtils.openNewForegroundTab(
+    gBrowser,
+    TEST_PAGE
+  );
+
+  // Tear out the starting tab into its own window...
+  let newWinLoaded = BrowserTestUtils.waitForNewWindow();
+  let win2 = gBrowser.replaceTabWithWindow(startingTab);
+  await newWinLoaded;
+
+  // Let's maximize the newly opened window so we don't have to worry about
+  // the videos being visible.
+  if (win2.windowState != win2.STATE_MAXIMIZED) {
+    let resizePromise = BrowserTestUtils.waitForEvent(win2, "resize");
+    win2.maximize();
+    await resizePromise;
+  }
+
+  await SimpleTest.promiseFocus(win2);
+  await testToggleForTab(win2.gBrowser.selectedTab);
+
+  // Now bring the tab back to the original window.
+  let dragInTab = await BrowserTestUtils.openNewForegroundTab(gBrowser);
+  gBrowser.swapBrowsersAndCloseOther(dragInTab, win2.gBrowser.selectedTab);
+  await SimpleTest.promiseFocus(window);
+  await testToggleForTab(dragInTab);
+
+  BrowserTestUtils.removeTab(dragInTab);
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_toggleButtonOnNanDuration.js b/toolkit/components/pictureinpicture/tests/browser_toggleButtonOnNanDuration.js
new file mode 100644
index 0000000000..6eaa4b5bcd
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_toggleButtonOnNanDuration.js
@@ -0,0 +1,32 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests that we do not show the Picture-in-Picture toggle on video
+ * elements that have a NaN duration.
+ */
+add_task(async function test_toggleButtonOnNanDuration() {
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE_WITH_NAN_VIDEO_DURATION,
+      gBrowser,
+    },
+    async browser => {
+      const VIDEO_ID = "test-video";
+
+      await SpecialPowers.spawn(browser, [VIDEO_ID], async videoID => {
+        let video = content.document.getElementById(videoID);
+        if (video.readyState < content.HTMLMediaElement.HAVE_ENOUGH_DATA) {
+          info(`Waiting for 'canplaythrough' for ${videoID}`);
+          await ContentTaskUtils.waitForEvent(video, "canplaythrough");
+        }
+      });
+
+      await testToggleHelper(browser, "nan-duration", false);
+
+      await testToggleHelper(browser, "test-video", true);
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_toggleButtonOverlay.js b/toolkit/components/pictureinpicture/tests/browser_toggleButtonOverlay.js
new file mode 100644
index 0000000000..6f81075770
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_toggleButtonOverlay.js
@@ -0,0 +1,17 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests that the Picture-in-Picture toggle can be clicked when overlaid
+ * with a transparent button, but not clicked when overlaid with an
+ * opaque button.
+ */
+add_task(async () => {
+  const PAGE = TEST_ROOT + "test-button-overlay.html";
+  await testToggle(PAGE, {
+    "video-partial-transparent-button": { canToggle: true },
+    "video-opaque-button": { canToggle: false },
+  });
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_toggleMode_2.js b/toolkit/components/pictureinpicture/tests/browser_toggleMode_2.js
new file mode 100644
index 0000000000..ea94e2b2ff
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_toggleMode_2.js
@@ -0,0 +1,202 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * See the documentation for the DEFAULT_TOGGLE_STYLES object in head.js
+ * for a description of what these toggle style objects are representing.
+ */
+const TOGGLE_STYLES_LEFT_EXPLAINER = {
+  rootID: "pictureInPictureToggle",
+  stages: {
+    hoverVideo: {
+      opacities: {
+        ".pip-small": 0.0,
+        ".pip-wrapper": DEFAULT_TOGGLE_OPACITY,
+        ".pip-expanded": 1.0,
+      },
+      hidden: [".pip-icon-label > .pip-icon"],
+    },
+
+    hoverToggle: {
+      opacities: {
+        ".pip-small": 0.0,
+        ".pip-wrapper": 1.0,
+        ".pip-expanded": 1.0,
+      },
+      hidden: [".pip-icon-label > .pip-icon"],
+    },
+  },
+};
+
+const TOGGLE_STYLES_RIGHT_EXPLAINER = {
+  rootID: "pictureInPictureToggle",
+  stages: {
+    hoverVideo: {
+      opacities: {
+        ".pip-small": 0.0,
+        ".pip-wrapper": DEFAULT_TOGGLE_OPACITY,
+        ".pip-expanded": 1.0,
+      },
+      hidden: [".pip-wrapper > .pip-icon"],
+    },
+
+    hoverToggle: {
+      opacities: {
+        ".pip-small": 0.0,
+        ".pip-wrapper": 1.0,
+        ".pip-expanded": 1.0,
+      },
+      hidden: [".pip-wrapper > .pip-icon"],
+    },
+  },
+};
+
+const TOGGLE_STYLES_LEFT_SMALL = {
+  rootID: "pictureInPictureToggle",
+  stages: {
+    hoverVideo: {
+      opacities: {
+        ".pip-wrapper": DEFAULT_TOGGLE_OPACITY,
+      },
+      hidden: [".pip-expanded"],
+    },
+
+    hoverToggle: {
+      opacities: {
+        ".pip-wrapper": 1.0,
+      },
+      hidden: [".pip-expanded"],
+    },
+  },
+};
+
+const TOGGLE_STYLES_RIGHT_SMALL = {
+  rootID: "pictureInPictureToggle",
+  stages: {
+    hoverVideo: {
+      opacities: {
+        ".pip-wrapper": DEFAULT_TOGGLE_OPACITY,
+      },
+      hidden: [".pip-expanded"],
+    },
+
+    hoverToggle: {
+      opacities: {
+        ".pip-wrapper": 1.0,
+      },
+      hidden: [".pip-expanded"],
+    },
+  },
+};
+
+/**
+ * Tests the Mode 2 variation of the Picture-in-Picture toggle in both the
+ * left and right positions, when the user is in the state where they've never
+ * clicked on the Picture-in-Picture toggle before (since we show a more detailed
+ * toggle in that state).
+ */
+add_task(async () => {
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      ["media.videocontrols.picture-in-picture.video-toggle.position", "left"],
+      [HAS_USED_PREF, false],
+    ],
+  });
+
+  await testToggle(TEST_PAGE, {
+    "with-controls": {
+      canToggle: true,
+      toggleStyles: TOGGLE_STYLES_LEFT_EXPLAINER,
+    },
+  });
+
+  Assert.ok(
+    Services.prefs.getBoolPref(HAS_USED_PREF, false),
+    "Entered has-used mode."
+  );
+  Services.prefs.clearUserPref(HAS_USED_PREF);
+
+  await testToggle(TEST_PAGE, {
+    "no-controls": {
+      canToggle: true,
+      toggleStyles: TOGGLE_STYLES_LEFT_EXPLAINER,
+    },
+  });
+
+  Assert.ok(
+    Services.prefs.getBoolPref(HAS_USED_PREF, false),
+    "Entered has-used mode."
+  );
+  Services.prefs.clearUserPref(HAS_USED_PREF);
+
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      ["media.videocontrols.picture-in-picture.video-toggle.position", "right"],
+    ],
+  });
+
+  await testToggle(TEST_PAGE, {
+    "with-controls": {
+      canToggle: true,
+      toggleStyles: TOGGLE_STYLES_RIGHT_EXPLAINER,
+    },
+  });
+
+  Assert.ok(
+    Services.prefs.getBoolPref(HAS_USED_PREF, false),
+    "Entered has-used mode."
+  );
+  Services.prefs.clearUserPref(HAS_USED_PREF);
+
+  await testToggle(TEST_PAGE, {
+    "no-controls": {
+      canToggle: true,
+      toggleStyles: TOGGLE_STYLES_RIGHT_EXPLAINER,
+    },
+  });
+
+  Assert.ok(
+    Services.prefs.getBoolPref(HAS_USED_PREF, false),
+    "Entered has-used mode."
+  );
+  Services.prefs.clearUserPref(HAS_USED_PREF);
+});
+
+/**
+ * Tests the Mode 2 variation of the Picture-in-Picture toggle in both the
+ * left and right positions, when the user is in the state where they've
+ * used the Picture-in-Picture feature before.
+ */
+add_task(async () => {
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      ["media.videocontrols.picture-in-picture.video-toggle.mode", 2],
+      ["media.videocontrols.picture-in-picture.video-toggle.position", "left"],
+      [HAS_USED_PREF, true],
+    ],
+  });
+
+  await testToggle(TEST_PAGE, {
+    "with-controls": {
+      canToggle: true,
+      toggleStyles: TOGGLE_STYLES_LEFT_SMALL,
+    },
+    "no-controls": { canToggle: true, toggleStyles: TOGGLE_STYLES_LEFT_SMALL },
+  });
+
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      ["media.videocontrols.picture-in-picture.video-toggle.position", "right"],
+    ],
+  });
+
+  await testToggle(TEST_PAGE, {
+    "with-controls": {
+      canToggle: true,
+      toggleStyles: TOGGLE_STYLES_LEFT_SMALL,
+    },
+    "no-controls": { canToggle: true, toggleStyles: TOGGLE_STYLES_LEFT_SMALL },
+  });
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_toggleOnInsertedVideo.js b/toolkit/components/pictureinpicture/tests/browser_toggleOnInsertedVideo.js
new file mode 100644
index 0000000000..36172feeb4
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_toggleOnInsertedVideo.js
@@ -0,0 +1,42 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests that the Picture-in-Picture toggle correctly attaches itself when the
+ * video element has been inserted into the DOM after the video is ready to
+ * play.
+ */
+add_task(async () => {
+  const PAGE = TEST_ROOT + "test-page.html";
+
+  await testToggle(
+    PAGE,
+    {
+      inserted: { canToggle: true },
+    },
+    async browser => {
+      await SpecialPowers.spawn(browser, [], async () => {
+        let doc = content.document;
+
+        // To avoid issues with the video not being scrolled into view, get
+        // rid of the other videos on the page.
+        let preExistingVideos = doc.querySelectorAll("video");
+        for (let video of preExistingVideos) {
+          video.remove();
+        }
+
+        let newVideo = doc.createElement("video");
+        const { ContentTaskUtils } = ChromeUtils.importESModule(
+          "resource://testing-common/ContentTaskUtils.sys.mjs"
+        );
+        let ready = ContentTaskUtils.waitForEvent(newVideo, "canplay");
+        newVideo.src = "test-video.mp4";
+        newVideo.id = "inserted";
+        await ready;
+        doc.body.appendChild(newVideo);
+      });
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_toggleOpaqueOverlay.js b/toolkit/components/pictureinpicture/tests/browser_toggleOpaqueOverlay.js
new file mode 100644
index 0000000000..18c906bf20
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_toggleOpaqueOverlay.js
@@ -0,0 +1,16 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests that the Picture-in-Picture toggle is not clickable when
+ * overlaid with opaque elements.
+ */
+add_task(async () => {
+  const PAGE = TEST_ROOT + "test-opaque-overlay.html";
+  await testToggle(PAGE, {
+    "video-full-opacity": { canToggle: false },
+    "video-full-opacity-over-toggle": { canToggle: false },
+  });
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_togglePointerEventsNone.js b/toolkit/components/pictureinpicture/tests/browser_togglePointerEventsNone.js
new file mode 100644
index 0000000000..23cc393960
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_togglePointerEventsNone.js
@@ -0,0 +1,16 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests that the Picture-in-Picture toggle is clickable even if the
+ * video element has pointer-events: none.
+ */
+add_task(async () => {
+  const PAGE = TEST_ROOT + "test-pointer-events-none.html";
+  await testToggle(PAGE, {
+    "with-controls": { canToggle: true },
+    "no-controls": { canToggle: true },
+  });
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_togglePolicies.js b/toolkit/components/pictureinpicture/tests/browser_togglePolicies.js
new file mode 100644
index 0000000000..a95bbb0d48
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_togglePolicies.js
@@ -0,0 +1,127 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests that by setting a Picture-in-Picture toggle position policy
+ * in the sharedData structure, that the toggle position can be
+ * change for a particular URI.
+ */
+add_task(async () => {
+  let positionPolicies = [
+    TOGGLE_POLICIES.TOP,
+    TOGGLE_POLICIES.ONE_QUARTER,
+    TOGGLE_POLICIES.MIDDLE,
+    TOGGLE_POLICIES.THREE_QUARTERS,
+    TOGGLE_POLICIES.BOTTOM,
+  ];
+
+  for (let policy of positionPolicies) {
+    Services.ppmm.sharedData.set(SHARED_DATA_KEY, {
+      "*://example.com/*": { policy },
+    });
+    Services.ppmm.sharedData.flush();
+
+    let expectations = {
+      "with-controls": { canToggle: true, policy },
+      "no-controls": { canToggle: true, policy },
+    };
+
+    // For <video> elements with controls, the video controls overlap the
+    // toggle when its on the bottom and can't be clicked, so we'll ignore
+    // that case.
+    if (policy == TOGGLE_POLICIES.BOTTOM) {
+      expectations["with-controls"] = { canToggle: true };
+    }
+
+    await testToggle(TEST_PAGE, expectations);
+
+    // And ensure that other pages aren't affected by this override.
+    await testToggle(TEST_PAGE_2, {
+      "with-controls": { canToggle: true },
+      "no-controls": { canToggle: true },
+    });
+  }
+
+  Services.ppmm.sharedData.set(SHARED_DATA_KEY, {});
+  Services.ppmm.sharedData.flush();
+});
+
+/**
+ * Tests that by setting a Picture-in-Picture toggle hidden policy
+ * in the sharedData structure, that the toggle can be suppressed.
+ */
+add_task(async () => {
+  Services.ppmm.sharedData.set(SHARED_DATA_KEY, {
+    "*://example.com/*": { policy: TOGGLE_POLICIES.HIDDEN },
+  });
+  Services.ppmm.sharedData.flush();
+
+  await testToggle(TEST_PAGE, {
+    "with-controls": { canToggle: false, policy: TOGGLE_POLICIES.HIDDEN },
+    "no-controls": { canToggle: false, policy: TOGGLE_POLICIES.HIDDEN },
+  });
+
+  // And ensure that other pages aren't affected by this override.
+  await testToggle(TEST_PAGE_2, {
+    "with-controls": { canToggle: true },
+    "no-controls": { canToggle: true },
+  });
+
+  Services.ppmm.sharedData.set(SHARED_DATA_KEY, {});
+  Services.ppmm.sharedData.flush();
+});
+
+/**
+ * Tests that policies are re-evaluated if the page URI is transitioned
+ * via the history API.
+ */
+add_task(async () => {
+  Services.ppmm.sharedData.set(SHARED_DATA_KEY, {
+    "*://example.com/*/test-page.html": { policy: TOGGLE_POLICIES.HIDDEN },
+  });
+  Services.ppmm.sharedData.flush();
+
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: TEST_PAGE,
+    },
+    async browser => {
+      await ensureVideosReady(browser);
+      await SimpleTest.promiseFocus(browser);
+
+      await testToggleHelper(
+        browser,
+        "no-controls",
+        false,
+        TOGGLE_POLICIES.HIDDEN
+      );
+
+      await SpecialPowers.spawn(browser, [], async function () {
+        content.history.pushState({}, "2", "otherpage.html");
+      });
+
+      // Since we no longer match the policy URI, we should be able
+      // to use the Picture-in-Picture toggle.
+      await testToggleHelper(browser, "no-controls", true);
+
+      // Now use the history API to put us back at the original location,
+      // which should have the HIDDEN policy re-applied.
+      await SpecialPowers.spawn(browser, [], async function () {
+        content.history.pushState({}, "Return", "test-page.html");
+      });
+
+      await testToggleHelper(
+        browser,
+        "no-controls",
+        false,
+        TOGGLE_POLICIES.HIDDEN
+      );
+    }
+  );
+
+  Services.ppmm.sharedData.set(SHARED_DATA_KEY, {});
+  Services.ppmm.sharedData.flush();
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_togglePositionChange.js b/toolkit/components/pictureinpicture/tests/browser_togglePositionChange.js
new file mode 100644
index 0000000000..a868bc3d71
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_togglePositionChange.js
@@ -0,0 +1,58 @@
+/* Any copyright is dedicated to the Public Domain.
+http://creativecommons.org/publicdomain/zero/1.0/ */
+"use strict";
+
+/**
+ * Tests that Picture-in-Picture "move toggle" context menu item
+ * successfully changes preference.
+ */
+add_task(async () => {
+  let videoID = "with-controls";
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE,
+      gBrowser,
+    },
+    async browser => {
+      await ensureVideosReady(browser);
+
+      await SpecialPowers.spawn(browser, [videoID], async videoID => {
+        await content.document.getElementById(videoID).play();
+      });
+
+      const TOGGLE_POSITION_PREF =
+        "media.videocontrols.picture-in-picture.video-toggle.position";
+      const TOGGLE_POSITION_RIGHT = "right";
+      const TOGGLE_POSITION_LEFT = "left";
+
+      await SpecialPowers.pushPrefEnv({
+        set: [[TOGGLE_POSITION_PREF, TOGGLE_POSITION_RIGHT]],
+      });
+
+      let contextMoveToggle = document.getElementById(
+        "context_MovePictureInPictureToggle"
+      );
+      contextMoveToggle.click();
+      let position = Services.prefs.getStringPref(
+        TOGGLE_POSITION_PREF,
+        TOGGLE_POSITION_RIGHT
+      );
+
+      Assert.ok(
+        position === TOGGLE_POSITION_LEFT,
+        "Picture-in-Picture toggle position value should be 'left'."
+      );
+
+      contextMoveToggle.click();
+      position = Services.prefs.getStringPref(
+        TOGGLE_POSITION_PREF,
+        TOGGLE_POSITION_RIGHT
+      );
+
+      Assert.ok(
+        position === TOGGLE_POSITION_RIGHT,
+        "Picture-in-Picture toggle position value should be 'right'."
+      );
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_toggleSimple.js b/toolkit/components/pictureinpicture/tests/browser_toggleSimple.js
new file mode 100644
index 0000000000..a9351816fa
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_toggleSimple.js
@@ -0,0 +1,18 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests that we show the Picture-in-Picture toggle on video
+ * elements when hovering them with the mouse cursor, and that
+ * clicking on them causes the Picture-in-Picture window to
+ * open if the toggle isn't being occluded. This test tests videos
+ * both with and without controls.
+ */
+add_task(async () => {
+  await testToggle(TEST_PAGE, {
+    "with-controls": { canToggle: true },
+    "no-controls": { canToggle: true },
+  });
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_toggleTransparentOverlay-1.js b/toolkit/components/pictureinpicture/tests/browser_toggleTransparentOverlay-1.js
new file mode 100644
index 0000000000..658bb0f362
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_toggleTransparentOverlay-1.js
@@ -0,0 +1,33 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests that the Picture-in-Picture toggle can appear and be clicked
+ * when the video is overlaid with transparent elements. Also tests the
+ * site-specific toggle visibility threshold to ensure that we can
+ * configure opacities that can't be clicked through.
+ */
+add_task(async () => {
+  const PAGE = TEST_ROOT + "test-transparent-overlay-1.html";
+  await testToggle(PAGE, {
+    "video-transparent-background": { canToggle: true },
+    "video-alpha-background": { canToggle: true },
+  });
+
+  // Now set a toggle visibility threshold to 0.4 and ensure that the
+  // partially obscured toggle can't be clicked.
+  Services.ppmm.sharedData.set(SHARED_DATA_KEY, {
+    "*://example.com/*": { visibilityThreshold: 0.4 },
+  });
+  Services.ppmm.sharedData.flush();
+
+  await testToggle(PAGE, {
+    "video-transparent-background": { canToggle: true },
+    "video-alpha-background": { canToggle: false },
+  });
+
+  Services.ppmm.sharedData.set(SHARED_DATA_KEY, {});
+  Services.ppmm.sharedData.flush();
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_toggleTransparentOverlay-2.js b/toolkit/components/pictureinpicture/tests/browser_toggleTransparentOverlay-2.js
new file mode 100644
index 0000000000..b425b50d1c
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_toggleTransparentOverlay-2.js
@@ -0,0 +1,33 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests that the Picture-in-Picture toggle can appear and be clicked
+ * when the video is overlaid with elements that have zero and partial
+ * opacity. Also tests the site-specific toggle visibility threshold to
+ * ensure that we can configure opacities that can't be clicked through.
+ */
+add_task(async () => {
+  const PAGE = TEST_ROOT + "test-transparent-overlay-2.html";
+  await testToggle(PAGE, {
+    "video-zero-opacity": { canToggle: true },
+    "video-partial-opacity": { canToggle: true },
+  });
+
+  // Now set a toggle visibility threshold to 0.4 and ensure that the
+  // partially obscured toggle can't be clicked.
+  Services.ppmm.sharedData.set(SHARED_DATA_KEY, {
+    "*://example.com/*": { visibilityThreshold: 0.4 },
+  });
+  Services.ppmm.sharedData.flush();
+
+  await testToggle(PAGE, {
+    "video-zero-opacity": { canToggle: true },
+    "video-partial-opacity": { canToggle: false },
+  });
+
+  Services.ppmm.sharedData.set(SHARED_DATA_KEY, {});
+  Services.ppmm.sharedData.flush();
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_toggle_enabled.js b/toolkit/components/pictureinpicture/tests/browser_toggle_enabled.js
new file mode 100644
index 0000000000..197bb9357c
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_toggle_enabled.js
@@ -0,0 +1,99 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const videoID = "with-controls";
+const TOGGLE_ENABLED_PREF =
+  "media.videocontrols.picture-in-picture.video-toggle.enabled";
+const PIP_ENABLED_PREF = "media.videocontrols.picture-in-picture.enabled";
+const ACCEPTABLE_DIFF = 1;
+
+function checkDifference(actual, expected) {
+  let diff = Math.abs(actual - expected);
+  return diff <= ACCEPTABLE_DIFF;
+}
+
+function isVideoRect(videoRect, rect) {
+  info(
+    "Video rect and toggle rect will be the same if the toggle doesn't show"
+  );
+  info(`Video rect: ${JSON.stringify(videoRect)}`);
+  info(`Toggle rect: ${JSON.stringify(rect)}`);
+  return (
+    checkDifference(videoRect.top, rect.top) &&
+    checkDifference(videoRect.left, rect.left) &&
+    checkDifference(videoRect.width, rect.width) &&
+    checkDifference(videoRect.height, rect.height)
+  );
+}
+
+/**
+ * Tests if the toggle is available depending on prefs
+ */
+add_task(async () => {
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: TEST_PAGE,
+    },
+    async browser => {
+      let videoRect = await SpecialPowers.spawn(
+        browser,
+        [videoID],
+        async videoID => {
+          let video = content.document.getElementById(videoID);
+          let rect = video.getBoundingClientRect();
+
+          return {
+            top: rect.top,
+            left: rect.left,
+            width: rect.width,
+            height: rect.height,
+          };
+        }
+      );
+      // both toggle and pip true
+      await SpecialPowers.pushPrefEnv({
+        set: [
+          [TOGGLE_ENABLED_PREF, true],
+          [PIP_ENABLED_PREF, true],
+        ],
+      });
+
+      let rect = await getToggleClientRect(browser, videoID);
+
+      Assert.ok(!isVideoRect(videoRect, rect), "Toggle is showing");
+
+      // only toggle false
+      await SpecialPowers.pushPrefEnv({
+        set: [[TOGGLE_ENABLED_PREF, false]],
+      });
+
+      rect = await getToggleClientRect(browser, videoID);
+      Assert.ok(isVideoRect(videoRect, rect), "The toggle is not showing");
+
+      // only pip false
+      await SpecialPowers.pushPrefEnv({
+        set: [
+          [TOGGLE_ENABLED_PREF, true],
+          [PIP_ENABLED_PREF, false],
+        ],
+      });
+
+      rect = await getToggleClientRect(browser, videoID);
+      Assert.ok(isVideoRect(videoRect, rect), "The toggle is not showing");
+
+      // both toggle and pip false
+      await SpecialPowers.pushPrefEnv({
+        set: [
+          [TOGGLE_ENABLED_PREF, false],
+          [PIP_ENABLED_PREF, false],
+        ],
+      });
+
+      rect = await getToggleClientRect(browser, videoID);
+      Assert.ok(isVideoRect(videoRect, rect), "The toggle is not showing");
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_toggle_videocontrols.js b/toolkit/components/pictureinpicture/tests/browser_toggle_videocontrols.js
new file mode 100644
index 0000000000..248f816fba
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_toggle_videocontrols.js
@@ -0,0 +1,76 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests that the Picture-in-Picture toggle is hidden when opening the closed captions menu
+ * and is visible when closing the closed captions menu.
+ */
+add_task(async () => {
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      [
+        "media.videocontrols.picture-in-picture.display-text-tracks.enabled",
+        true,
+      ],
+      ["media.videocontrols.picture-in-picture.video-toggle.enabled", true],
+    ],
+  });
+  let videoID = "with-controls";
+
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE_WITH_WEBVTT,
+      gBrowser,
+    },
+    async browser => {
+      await prepareVideosAndWebVTTTracks(browser, videoID, -1);
+      await prepareForToggleClick(browser, videoID);
+
+      let args = {
+        videoID,
+        DEFAULT_TOGGLE_STYLES,
+      };
+
+      await SpecialPowers.spawn(browser, [args], async args => {
+        let { videoID, DEFAULT_TOGGLE_STYLES } = args;
+        let video = this.content.document.getElementById(videoID);
+        let shadowRoot = video.openOrClosedShadowRoot;
+        let closedCaptionButton = shadowRoot.querySelector(
+          "#closedCaptionButton"
+        );
+        let toggle = shadowRoot.querySelector(
+          `#${DEFAULT_TOGGLE_STYLES.rootID}`
+        );
+        let textTrackListContainer = shadowRoot.querySelector(
+          "#textTrackListContainer"
+        );
+
+        Assert.ok(!toggle.hidden, "Toggle should be visible");
+        Assert.ok(
+          textTrackListContainer.hidden,
+          "textTrackListContainer should be hidden"
+        );
+
+        info("Opening text track list from cc button");
+        closedCaptionButton.click();
+
+        Assert.ok(toggle.hidden, "Toggle should be hidden");
+        Assert.ok(
+          !textTrackListContainer.hidden,
+          "textTrackListContainer should be visible"
+        );
+
+        info("Clicking the cc button again to close it");
+        closedCaptionButton.click();
+
+        Assert.ok(!toggle.hidden, "Toggle should be visible again");
+        Assert.ok(
+          textTrackListContainer.hidden,
+          "textTrackListContainer should be hidden again"
+        );
+      });
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_toggle_without_audio.js b/toolkit/components/pictureinpicture/tests/browser_toggle_without_audio.js
new file mode 100644
index 0000000000..0c9ca5eeba
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_toggle_without_audio.js
@@ -0,0 +1,71 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const videoID = "without-audio";
+const MIN_DURATION_PREF =
+  "media.videocontrols.picture-in-picture.video-toggle.min-video-secs";
+const ALWAYS_SHOW_PREF =
+  "media.videocontrols.picture-in-picture.video-toggle.always-show";
+const ACCEPTABLE_DIFF = 1;
+
+function checkDifference(actual, expected) {
+  let diff = Math.abs(actual - expected);
+  return diff <= ACCEPTABLE_DIFF;
+}
+
+function isVideoRect(videoRect, rect) {
+  info(
+    "Video rect and toggle rect will be the same if the toggle doesn't show"
+  );
+  info(`Video rect: ${JSON.stringify(videoRect)}`);
+  info(`Toggle rect: ${JSON.stringify(rect)}`);
+  return (
+    checkDifference(videoRect.top, rect.top) &&
+    checkDifference(videoRect.left, rect.left) &&
+    checkDifference(videoRect.width, rect.width) &&
+    checkDifference(videoRect.height, rect.height)
+  );
+}
+
+/**
+ * Tests if the toggle is available for a video without an audio track
+ */
+add_task(async () => {
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: TEST_PAGE_WITHOUT_AUDIO,
+    },
+    async browser => {
+      let videoRect = await SpecialPowers.spawn(
+        browser,
+        [videoID],
+        async videoID => {
+          let video = content.document.getElementById(videoID);
+          Assert.ok(!video.mozHasAudio, "Video does not have an audio track");
+          let rect = video.getBoundingClientRect();
+
+          return {
+            top: rect.top,
+            left: rect.left,
+            width: rect.width,
+            height: rect.height,
+          };
+        }
+      );
+
+      await SpecialPowers.pushPrefEnv({
+        set: [
+          [ALWAYS_SHOW_PREF, false], // don't always show, we're testing the display logic
+          [MIN_DURATION_PREF, 3], // sample video is only 4s
+        ],
+      });
+
+      let rect = await getToggleClientRect(browser, videoID);
+
+      Assert.ok(!isVideoRect(videoRect, rect), "Toggle is showing");
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_touch_toggle_enablepip.js b/toolkit/components/pictureinpicture/tests/browser_touch_toggle_enablepip.js
new file mode 100644
index 0000000000..1fbb66257d
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_touch_toggle_enablepip.js
@@ -0,0 +1,217 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests that Picture-in-Picture intializes without changes to video playback
+ * when opened via the toggle using a touch event. Also ensures that elements
+ * in the content window can still be interacted with afterwards.
+ */
+add_task(async () => {
+  let videoID = "with-controls";
+
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      ["media.videocontrols.picture-in-picture.video-toggle.position", "right"],
+    ],
+  });
+
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE,
+      gBrowser,
+    },
+    async browser => {
+      await ensureVideosReady(browser);
+      let toggleStyles = DEFAULT_TOGGLE_STYLES;
+      let stage = "hoverVideo";
+      let toggleStylesForStage = toggleStyles.stages[stage];
+      let toggleClientRect = await getToggleClientRect(browser, videoID);
+
+      await SpecialPowers.spawn(
+        browser,
+        [{ videoID, toggleClientRect, toggleStylesForStage }],
+        async args => {
+          // waitForToggleOpacity is based on toggleOpacityReachesThreshold.
+          // Waits for toggle to reach target opacity.
+          async function waitForToggleOpacity(
+            shadowRoot,
+            toggleStylesForStage
+          ) {
+            for (let hiddenElement of toggleStylesForStage.hidden) {
+              let el = shadowRoot.querySelector(hiddenElement);
+              ok(
+                ContentTaskUtils.is_hidden(el),
+                `Expected ${hiddenElement} to be hidden.`
+              );
+            }
+
+            for (let opacityElement in toggleStylesForStage.opacities) {
+              let opacityThreshold =
+                toggleStylesForStage.opacities[opacityElement];
+              let el = shadowRoot.querySelector(opacityElement);
+
+              await ContentTaskUtils.waitForCondition(
+                () => {
+                  let opacity = parseFloat(
+                    this.content.getComputedStyle(el).opacity
+                  );
+                  return opacity >= opacityThreshold;
+                },
+                `Toggle element ${opacityElement} should have eventually reached ` +
+                  `target opacity ${opacityThreshold}`,
+                100,
+                100
+              );
+
+              ok(true, "Toggle reached target opacity.");
+            }
+          }
+          let { videoID, toggleClientRect, toggleStylesForStage } = args;
+          let video = content.document.getElementById(videoID);
+          let shadowRoot = video.openOrClosedShadowRoot;
+
+          info("Creating a new button in the content window");
+          let button = this.content.document.createElement("button");
+          let buttonSelected = false;
+          button.ontouchstart = () => {
+            buttonSelected = true;
+            return true;
+          };
+          button.id = "testbutton";
+          this.content.document.body.appendChild(button);
+
+          await video.play();
+
+          info("Hover over the video to show the Picture-in-Picture toggle");
+          await EventUtils.synthesizeMouseAtCenter(
+            video,
+            { type: "mousemove" },
+            this.content.window
+          );
+          await EventUtils.synthesizeMouseAtCenter(
+            video,
+            { type: "mouseover" },
+            this.content.window
+          );
+
+          let toggleCenterX =
+            toggleClientRect.left + toggleClientRect.width / 2;
+          let toggleCenterY =
+            toggleClientRect.top + toggleClientRect.height / 2;
+
+          // We want to wait for the toggle to reach opacity so that we can select it.
+          info("Waiting for toggle to become fully visible");
+          await waitForToggleOpacity(shadowRoot, toggleStylesForStage);
+
+          info("Simulating touch event on PiP toggle");
+          let utils = EventUtils._getDOMWindowUtils(this.content.window);
+          let id = utils.DEFAULT_TOUCH_POINTER_ID;
+          let rx = 1;
+          let ry = 1;
+          let angle = 0;
+          let force = 1;
+          let tiltX = 0;
+          let tiltY = 0;
+          let twist = 0;
+
+          let defaultPrevented = utils.sendTouchEvent(
+            "touchstart",
+            [id],
+            [toggleCenterX],
+            [toggleCenterY],
+            [rx],
+            [ry],
+            [angle],
+            [force],
+            [tiltX],
+            [tiltY],
+            [twist],
+            false /* modifiers */
+          );
+          utils.sendTouchEvent(
+            "touchend",
+            [id],
+            [toggleCenterX],
+            [toggleCenterY],
+            [rx],
+            [ry],
+            [angle],
+            [force],
+            [tiltX],
+            [tiltY],
+            [twist],
+            false /* modifiers */
+          );
+
+          ok(
+            defaultPrevented,
+            "Touchstart event's default actions should be prevented"
+          );
+          ok(!video.paused, "Video should still be playing");
+
+          let testButton = this.content.document.getElementById("testbutton");
+          let buttonRect = testButton.getBoundingClientRect();
+          let buttonCenterX = buttonRect.left + buttonRect.width / 2;
+          let buttonCenterY = buttonRect.top + buttonRect.height / 2;
+
+          info("Simulating touch event on new button");
+          defaultPrevented = utils.sendTouchEvent(
+            "touchstart",
+            [id],
+            [buttonCenterX],
+            [buttonCenterY],
+            [rx],
+            [ry],
+            [angle],
+            [force],
+            [tiltX],
+            [tiltY],
+            [twist],
+            false /* modifiers */
+          );
+          utils.sendTouchEvent(
+            "touchend",
+            [id],
+            [buttonCenterX],
+            [buttonCenterY],
+            [rx],
+            [ry],
+            [angle],
+            [force],
+            [tiltX],
+            [tiltY],
+            [twist],
+            false /* modifiers */
+          );
+
+          ok(
+            buttonSelected,
+            "Button in content window was selected via touchstart"
+          );
+          ok(
+            !defaultPrevented,
+            "Touchstart event's default actions should no longer be prevented"
+          );
+        }
+      );
+
+      try {
+        info("Picture-in-Picture window should open");
+        await BrowserTestUtils.waitForCondition(
+          () => Services.wm.getEnumerator(WINDOW_TYPE).hasMoreElements(),
+          "Found a Picture-in-Picture"
+        );
+        for (let win of Services.wm.getEnumerator(WINDOW_TYPE)) {
+          if (!win.closed) {
+            ok(true, "Found a Picture-in-Picture window as expected");
+            win.close();
+          }
+        }
+      } catch {
+        ok(false, "No Picture-in-Picture window found, which is unexpected");
+      }
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_urlbar_toggle.js b/toolkit/components/pictureinpicture/tests/browser_urlbar_toggle.js
new file mode 100644
index 0000000000..1d75f96e88
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_urlbar_toggle.js
@@ -0,0 +1,329 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { TelemetryTestUtils } = ChromeUtils.importESModule(
+  "resource://testing-common/TelemetryTestUtils.sys.mjs"
+);
+
+const PIP_URLBAR_EVENTS = [
+  {
+    category: "pictureinpicture",
+    method: "opened_method",
+    object: "urlBar",
+  },
+];
+
+const PIP_DISABLED_EVENTS = [
+  {
+    category: "pictureinpicture",
+    method: "opened_method",
+    object: "urlBar",
+    extra: { disableDialog: "true" },
+  },
+  {
+    category: "pictureinpicture",
+    method: "disrespect_disable",
+    object: "urlBar",
+  },
+];
+
+add_task(async function test_urlbar_toggle_multiple_contexts() {
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE_MULTIPLE_CONTEXTS,
+      gBrowser,
+    },
+    async browser => {
+      Services.telemetry.clearEvents();
+      await ensureVideosReady(browser);
+      await ensureVideosReady(browser.browsingContext.children[0]);
+
+      await TestUtils.waitForCondition(
+        () =>
+          PictureInPicture.getEligiblePipVideoCount(browser).totalPipCount ===
+          2,
+        "Waiting for videos to register"
+      );
+
+      let { totalPipCount } =
+        PictureInPicture.getEligiblePipVideoCount(browser);
+      is(totalPipCount, 2, "Total PiP count is 2");
+
+      let pipUrlbarToggle = document.getElementById(
+        "picture-in-picture-button"
+      );
+      ok(
+        BrowserTestUtils.is_hidden(pipUrlbarToggle),
+        "PiP urlbar toggle is hidden because there is more than 1 video"
+      );
+
+      // Remove one video from page so urlbar toggle will show
+      await SpecialPowers.spawn(browser, [], async () => {
+        let video = content.document.getElementById("with-controls");
+        video.remove();
+      });
+
+      await BrowserTestUtils.waitForMutationCondition(
+        pipUrlbarToggle,
+        { attributeFilter: ["hidden"] },
+        () => BrowserTestUtils.is_visible(pipUrlbarToggle)
+      );
+
+      ok(
+        BrowserTestUtils.is_visible(pipUrlbarToggle),
+        "PiP urlbar toggle is visible"
+      );
+
+      ({ totalPipCount } = PictureInPicture.getEligiblePipVideoCount(browser));
+      is(totalPipCount, 1, "Total PiP count is 1");
+
+      let domWindowOpened = BrowserTestUtils.domWindowOpenedAndLoaded(null);
+      pipUrlbarToggle.click();
+      let win = await domWindowOpened;
+      ok(win, "A Picture-in-Picture window opened.");
+
+      await assertVideoIsBeingCloned(
+        browser.browsingContext.children[0],
+        "video"
+      );
+
+      let filter = {
+        category: "pictureinpicture",
+        method: "opened_method",
+        object: "urlBar",
+      };
+      await waitForTelemeryEvents(filter, PIP_URLBAR_EVENTS.length, "content");
+
+      TelemetryTestUtils.assertEvents(PIP_URLBAR_EVENTS, filter, {
+        clear: true,
+        process: "content",
+      });
+
+      let domWindowClosed = BrowserTestUtils.domWindowClosed(win);
+      pipUrlbarToggle.click();
+      await domWindowClosed;
+
+      await SpecialPowers.spawn(browser, [], async () => {
+        let iframe = content.document.getElementById("iframe");
+        iframe.remove();
+      });
+
+      await BrowserTestUtils.waitForMutationCondition(
+        pipUrlbarToggle,
+        { attributeFilter: ["hidden"] },
+        () => BrowserTestUtils.is_hidden(pipUrlbarToggle)
+      );
+
+      ok(
+        BrowserTestUtils.is_hidden(pipUrlbarToggle),
+        "PiP urlbar toggle is hidden because there are no videos on the page"
+      );
+
+      ({ totalPipCount } = PictureInPicture.getEligiblePipVideoCount(browser));
+      is(totalPipCount, 0, "Total PiP count is 0");
+    }
+  );
+});
+
+add_task(async function test_urlbar_toggle_switch_tabs() {
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE_TRANSPARENT_NESTED_IFRAMES,
+      gBrowser,
+    },
+    async browser => {
+      await ensureVideosReady(browser);
+
+      await TestUtils.waitForCondition(
+        () =>
+          PictureInPicture.getEligiblePipVideoCount(browser).totalPipCount ===
+          1,
+        "Waiting for video to register"
+      );
+
+      let { totalPipCount } =
+        PictureInPicture.getEligiblePipVideoCount(browser);
+      is(totalPipCount, 1, "Total PiP count is 1");
+
+      let pipUrlbarToggle = document.getElementById(
+        "picture-in-picture-button"
+      );
+      ok(
+        BrowserTestUtils.is_visible(pipUrlbarToggle),
+        "PiP urlbar toggle is visible because there is 1 video"
+      );
+
+      let pipActivePromise = BrowserTestUtils.waitForMutationCondition(
+        pipUrlbarToggle,
+        { attributeFilter: ["pipactive"] },
+        () => pipUrlbarToggle.hasAttribute("pipactive")
+      );
+
+      let domWindowOpened = BrowserTestUtils.domWindowOpenedAndLoaded(null);
+      pipUrlbarToggle.click();
+      let win = await domWindowOpened;
+      ok(win, "A Picture-in-Picture window opened.");
+
+      await assertVideoIsBeingCloned(browser, "video");
+
+      await pipActivePromise;
+
+      ok(
+        pipUrlbarToggle.hasAttribute("pipactive"),
+        "We are PiP'd in this tab so the icon is active"
+      );
+
+      let newTab = BrowserTestUtils.addTab(
+        gBrowser,
+        TEST_PAGE_TRANSPARENT_NESTED_IFRAMES
+      );
+      await BrowserTestUtils.browserLoaded(newTab.linkedBrowser);
+
+      await BrowserTestUtils.switchTab(gBrowser, newTab);
+
+      await BrowserTestUtils.waitForMutationCondition(
+        pipUrlbarToggle,
+        { attributeFilter: ["pipactive"] },
+        () => !pipUrlbarToggle.hasAttribute("pipactive")
+      );
+
+      ok(
+        !pipUrlbarToggle.hasAttribute("pipactive"),
+        "After switching tabs the pip icon is not active"
+      );
+
+      BrowserTestUtils.removeTab(newTab);
+
+      await ensureMessageAndClosePiP(
+        browser,
+        "video-transparent-background",
+        win,
+        false
+      );
+    }
+  );
+});
+
+add_task(async function test_pipDisabled() {
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE_PIP_DISABLED,
+      gBrowser,
+    },
+    async browser => {
+      Services.telemetry.clearEvents();
+      await SpecialPowers.pushPrefEnv({
+        set: [
+          [
+            "media.videocontrols.picture-in-picture.respect-disablePictureInPicture",
+            true,
+          ],
+        ],
+      });
+
+      const VIDEO_ID = "with-controls";
+      await ensureVideosReady(browser);
+
+      await TestUtils.waitForCondition(
+        () =>
+          PictureInPicture.getEligiblePipVideoCount(browser).totalPipCount ===
+          1,
+        "Waiting for video to register"
+      );
+
+      let { totalPipCount, totalPipDisabled } =
+        PictureInPicture.getEligiblePipVideoCount(browser);
+      is(totalPipCount, 1, "Total PiP count is 1");
+      is(totalPipDisabled, 1, "PiP is disabled on 1 video");
+
+      // Confirm that the toggle is hidden because we are respecting disablePictureInPicture
+      await testToggleHelper(browser, VIDEO_ID, false);
+
+      let pipUrlbarToggle = document.getElementById(
+        "picture-in-picture-button"
+      );
+      ok(
+        BrowserTestUtils.is_visible(pipUrlbarToggle),
+        "PiP urlbar toggle is visible because PiP is disabled"
+      );
+
+      pipUrlbarToggle.click();
+
+      let panel = browser.ownerDocument.querySelector("#PictureInPicturePanel");
+      await BrowserTestUtils.waitForCondition(async () => {
+        if (!panel) {
+          panel = browser.ownerDocument.querySelector("#PictureInPicturePanel");
+        }
+        return BrowserTestUtils.is_visible(panel);
+      });
+
+      let respectPipDisableSwitch = panel.querySelector(
+        "#respect-pipDisabled-switch"
+      );
+      ok(
+        !respectPipDisableSwitch.pressed,
+        "Respect PiP disabled is not pressed"
+      );
+
+      EventUtils.synthesizeMouseAtCenter(respectPipDisableSwitch.buttonEl, {});
+      await BrowserTestUtils.waitForEvent(respectPipDisableSwitch, "toggle");
+      ok(respectPipDisableSwitch.pressed, "Respect PiP disabled is pressed");
+
+      pipUrlbarToggle.click();
+
+      await BrowserTestUtils.waitForCondition(async () => {
+        return BrowserTestUtils.is_hidden(panel);
+      });
+
+      let filter = {
+        category: "pictureinpicture",
+        object: "urlBar",
+      };
+      await waitForTelemeryEvents(filter, PIP_DISABLED_EVENTS.length, "parent");
+      TelemetryTestUtils.assertEvents(PIP_DISABLED_EVENTS, filter, {
+        clear: true,
+        process: "parent",
+      });
+
+      // Confirm that the toggle is now visible because we no longer respect disablePictureInPicture
+      await testToggleHelper(browser, VIDEO_ID, true);
+
+      let pipActivePromise = BrowserTestUtils.waitForMutationCondition(
+        pipUrlbarToggle,
+        { attributeFilter: ["pipactive"] },
+        () => pipUrlbarToggle.hasAttribute("pipactive")
+      );
+
+      let domWindowOpened = BrowserTestUtils.domWindowOpenedAndLoaded(null);
+      pipUrlbarToggle.click();
+      let win = await domWindowOpened;
+      ok(win, "A Picture-in-Picture window opened.");
+
+      await assertVideoIsBeingCloned(browser, "video");
+
+      await pipActivePromise;
+
+      ok(
+        pipUrlbarToggle.hasAttribute("pipactive"),
+        "We are PiP'd in this tab so the icon is active"
+      );
+
+      let domWindowClosed = BrowserTestUtils.domWindowClosed(win);
+      pipUrlbarToggle.click();
+      await domWindowClosed;
+
+      await BrowserTestUtils.waitForMutationCondition(
+        pipUrlbarToggle,
+        { attributeFilter: ["pipactive"] },
+        () => !pipUrlbarToggle.hasAttribute("pipactive")
+      );
+
+      ok(
+        !pipUrlbarToggle.hasAttribute("pipactive"),
+        "We closed the PiP window so the urlbar button is no longer active"
+      );
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_videoEmptied.js b/toolkit/components/pictureinpicture/tests/browser_videoEmptied.js
new file mode 100644
index 0000000000..bc96a9ea58
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_videoEmptied.js
@@ -0,0 +1,155 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests that the subtitles button hides after switching to a video that does not have subtitles
+ */
+add_task(async () => {
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      [
+        "media.videocontrols.picture-in-picture.display-text-tracks.enabled",
+        true,
+      ],
+    ],
+  });
+
+  let videoID = "with-controls";
+
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE_WITH_WEBVTT,
+      gBrowser,
+    },
+    async browser => {
+      await prepareVideosAndWebVTTTracks(browser, videoID);
+
+      let pipWin = await triggerPictureInPicture(browser, videoID);
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      // Need to make sure that the PiP window is at least the minimum height
+      let multiplier = 1;
+      while (true) {
+        if (multiplier * pipWin.innerHeight > 325) {
+          break;
+        }
+        multiplier += 0.5;
+      }
+
+      pipWin.moveTo(50, 50);
+      pipWin.resizeTo(
+        pipWin.innerWidth * multiplier,
+        pipWin.innerHeight * multiplier
+      );
+
+      let subtitlesButton = pipWin.document.querySelector("#closed-caption");
+      await TestUtils.waitForCondition(() => {
+        return !subtitlesButton.disabled;
+      }, "Waiting for subtitles button to be enabled");
+      ok(!subtitlesButton.disabled, "The subtitles button is enabled");
+
+      let emptied = SpecialPowers.spawn(browser, [{ videoID }], async args => {
+        let video = content.document.getElementById(args.videoID);
+        info("Waiting for emptied event to be called");
+        await ContentTaskUtils.waitForEvent(video, "emptied");
+      });
+
+      await SpecialPowers.spawn(browser, [{ videoID }], async args => {
+        let video = content.document.getElementById(args.videoID);
+        video.setAttribute("src", video.src);
+        let len = video.textTracks.length;
+        for (let i = 0; i < len; i++) {
+          video.removeChild(video.children[0]);
+        }
+        video.load();
+      });
+
+      await emptied;
+
+      await TestUtils.waitForCondition(() => {
+        return subtitlesButton.disabled;
+      }, "Waiting for subtitles button to be disabled after it was enabled");
+      ok(subtitlesButton.disabled, "The subtitles button is disabled");
+
+      await BrowserTestUtils.closeWindow(pipWin);
+    }
+  );
+});
+
+/**
+ * Tests the the subtitles button shows after switching from a video with no subtitles to a video with subtitles
+ */
+add_task(async () => {
+  const videoID = "with-controls";
+  const videoID2 = "with-controls-no-tracks";
+
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_PAGE_WITH_WEBVTT,
+      gBrowser,
+    },
+    async browser => {
+      let pipWin = await triggerPictureInPicture(browser, videoID2);
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      // Need to make sure that the PiP window is at least the minimum height
+      let multiplier = 1;
+      while (true) {
+        if (multiplier * pipWin.innerHeight > 325) {
+          break;
+        }
+        multiplier += 0.5;
+      }
+
+      pipWin.moveTo(50, 50);
+      pipWin.resizeTo(
+        pipWin.innerWidth * multiplier,
+        pipWin.innerHeight * multiplier
+      );
+
+      let subtitlesButton = pipWin.document.querySelector("#closed-caption");
+      await TestUtils.waitForCondition(() => {
+        return subtitlesButton.disabled;
+      }, "Making sure the subtitles button is disabled initially");
+      ok(subtitlesButton.disabled, "The subtitles button is disabled");
+
+      await SpecialPowers.spawn(
+        browser,
+        [{ videoID, videoID2 }],
+        async args => {
+          let video2 = content.document.getElementById(args.videoID2);
+
+          let track = video2.addTextTrack("captions", "English", "en");
+          track.mode = "showing";
+          track.addCue(
+            new content.window.VTTCue(0, 12, "[Test] This is the first cue")
+          );
+          track.addCue(
+            new content.window.VTTCue(18.7, 21.5, "This is the second cue")
+          );
+
+          video2.setAttribute("src", video2.src);
+          video2.load();
+
+          is(
+            video2.textTracks.length,
+            1,
+            "Number of tracks loaded should be 1"
+          );
+          video2.play();
+          video2.pause();
+        }
+      );
+
+      subtitlesButton = pipWin.document.querySelector("#closed-caption");
+      await TestUtils.waitForCondition(() => {
+        return !subtitlesButton.disabled;
+      }, "Waiting for the subtitles button to be enabled after switching to a video with subtitles.");
+      ok(!subtitlesButton.disabled, "The subtitles button is enabled");
+
+      await BrowserTestUtils.closeWindow(pipWin);
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/browser_videoSelection.js b/toolkit/components/pictureinpicture/tests/browser_videoSelection.js
new file mode 100644
index 0000000000..f887f158c1
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/browser_videoSelection.js
@@ -0,0 +1,106 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Tests that the correct video is opened in the
+ * Picture-in-Picture player when opened via keyboard shortcut.
+ * The shortcut will open the first unpaused video
+ * or the longest video on the page.
+ */
+add_task(async function test_video_selection() {
+  await BrowserTestUtils.withNewTab(
+    {
+      url: TEST_ROOT + "test-video-selection.html",
+      gBrowser,
+    },
+    async browser => {
+      await ensureVideosReady(browser);
+
+      let pipVideoID = await SpecialPowers.spawn(browser, [], () => {
+        let videoList = content.document.querySelectorAll("video");
+        let longestDuration = -1;
+        let pipVideoID = null;
+
+        for (let video of videoList) {
+          if (!video.paused) {
+            pipVideoID = video.id;
+            break;
+          }
+          if (video.duration > longestDuration) {
+            pipVideoID = video.id;
+            longestDuration = video.duration;
+          }
+        }
+        return pipVideoID;
+      });
+
+      let domWindowOpened = BrowserTestUtils.domWindowOpenedAndLoaded(null);
+      let videoReady = SpecialPowers.spawn(
+        browser,
+        [pipVideoID],
+        async videoID => {
+          let video = content.document.getElementById(videoID);
+          await ContentTaskUtils.waitForCondition(() => {
+            return video.isCloningElementVisually;
+          }, "Video is being cloned visually.");
+        }
+      );
+
+      let eventObj = { accelKey: true, shiftKey: true };
+      if (AppConstants.platform == "macosx") {
+        eventObj.altKey = true;
+      }
+      EventUtils.synthesizeKey("]", eventObj, window);
+
+      let pipWin = await domWindowOpened;
+      await videoReady;
+
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      await ensureMessageAndClosePiP(browser, pipVideoID, pipWin, false);
+
+      pipVideoID = await SpecialPowers.spawn(browser, [], () => {
+        let videoList = content.document.querySelectorAll("video");
+        videoList[1].play();
+        videoList[2].play();
+        let longestDuration = -1;
+        let pipVideoID = null;
+
+        for (let video of videoList) {
+          if (!video.paused) {
+            pipVideoID = video.id;
+            break;
+          }
+          if (video.duration > longestDuration) {
+            pipVideoID = video.id;
+            longestDuration = video.duration;
+          }
+        }
+
+        return pipVideoID;
+      });
+
+      // Next time we want to use a keyboard shortcut with the main window in focus again.
+      await SimpleTest.promiseFocus(browser);
+
+      domWindowOpened = BrowserTestUtils.domWindowOpenedAndLoaded(null);
+      videoReady = SpecialPowers.spawn(browser, [pipVideoID], async videoID => {
+        let video = content.document.getElementById(videoID);
+        await ContentTaskUtils.waitForCondition(() => {
+          return video.isCloningElementVisually;
+        }, "Video is being cloned visually.");
+      });
+
+      EventUtils.synthesizeKey("]", eventObj, window);
+
+      pipWin = await domWindowOpened;
+      await videoReady;
+
+      ok(pipWin, "Got Picture-in-Picture window.");
+
+      await ensureMessageAndClosePiP(browser, pipVideoID, pipWin, false);
+    }
+  );
+});
diff --git a/toolkit/components/pictureinpicture/tests/click-event-helper.js b/toolkit/components/pictureinpicture/tests/click-event-helper.js
new file mode 100644
index 0000000000..6b3ba42994
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/click-event-helper.js
@@ -0,0 +1,26 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/**
+ * This helper script is used to record mouse button events for
+ * Picture-in-Picture toggle click tests. Anytime the toggle is
+ * clicked, we expect none of the events to be fired. Otherwise,
+ * all events should be fired when clicking.
+ */
+
+let eventTypes = ["pointerdown", "mousedown", "pointerup", "mouseup", "click"];
+
+for (let event of eventTypes) {
+  addEventListener(event, recordEvent, { capture: true });
+}
+
+let recordedEvents = [];
+function recordEvent(event) {
+  recordedEvents.push(event.type);
+}
+
+function getRecordedEvents() {
+  let result = recordedEvents.concat();
+  recordedEvents = [];
+  return result;
+}
diff --git a/toolkit/components/pictureinpicture/tests/head.js b/toolkit/components/pictureinpicture/tests/head.js
new file mode 100644
index 0000000000..ba64ee2a77
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/head.js
@@ -0,0 +1,1110 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { TOGGLE_POLICIES } = ChromeUtils.importESModule(
+  "resource://gre/modules/PictureInPictureControls.sys.mjs"
+);
+
+const TEST_ROOT = getRootDirectory(gTestPath).replace(
+  "chrome://mochitests/content",
+  "http://example.com"
+);
+const TEST_ROOT_2 = getRootDirectory(gTestPath).replace(
+  "chrome://mochitests/content",
+  "http://example.org"
+);
+const TEST_PAGE = TEST_ROOT + "test-page.html";
+const TEST_PAGE_2 = TEST_ROOT_2 + "test-page.html";
+const TEST_PAGE_WITH_IFRAME = TEST_ROOT_2 + "test-page-with-iframe.html";
+const TEST_PAGE_WITH_SOUND = TEST_ROOT + "test-page-with-sound.html";
+const TEST_PAGE_WITHOUT_AUDIO = TEST_ROOT + "test-page-without-audio.html";
+const TEST_PAGE_WITH_NAN_VIDEO_DURATION =
+  TEST_ROOT + "test-page-with-nan-video-duration.html";
+const TEST_PAGE_WITH_WEBVTT = TEST_ROOT + "test-page-with-webvtt.html";
+const TEST_PAGE_MULTIPLE_CONTEXTS =
+  TEST_ROOT + "test-page-multiple-contexts.html";
+const TEST_PAGE_TRANSPARENT_NESTED_IFRAMES =
+  TEST_ROOT + "test-transparent-nested-iframes.html";
+const TEST_PAGE_PIP_DISABLED = TEST_ROOT + "test-page-pipDisabled.html";
+const WINDOW_TYPE = "Toolkit:PictureInPicture";
+const TOGGLE_POSITION_PREF =
+  "media.videocontrols.picture-in-picture.video-toggle.position";
+/* As of Bug 1811312, 80% toggle opacity is for the PiP toggle experiment control. */
+const DEFAULT_TOGGLE_OPACITY = 0.8;
+const HAS_USED_PREF =
+  "media.videocontrols.picture-in-picture.video-toggle.has-used";
+const SHARED_DATA_KEY = "PictureInPicture:SiteOverrides";
+// Used for clearing the size and location of the PiP window
+const PLAYER_URI = "chrome://global/content/pictureinpicture/player.xhtml";
+const ACCEPTABLE_DIFFERENCE = 2;
+
+/**
+ * We currently ship with a few different variations of the
+ * Picture-in-Picture toggle. The tests for Picture-in-Picture include tests
+ * that check the style rules of various parts of the toggle. Since each toggle
+ * variation has different style rules, we introduce a structure here to
+ * describe the appearance of the toggle at different stages for the tests.
+ *
+ * The top-level structure looks like this:
+ *
+ * {
+ *   rootID (String): The ID of the root element of the toggle.
+ *   stages (Object): An Object representing the styles of the toggle at
+ *     different stages of its use. Each property represents a different
+ *     stage that can be tested. Right now, those stages are:
+ *
+ *     hoverVideo:
+ *       When the mouse is hovering the video but not the toggle.
+ *
+ *     hoverToggle:
+ *       When the mouse is hovering both the video and the toggle.
+ *
+ *       Both stages must be assigned an Object with the following properties:
+ *
+ *       opacities:
+ *         This should be set to an Object where the key is a CSS selector for
+ *         an element, and the value is a double for what the eventual opacity
+ *         of that element should be set to.
+ *
+ *       hidden:
+ *         This should be set to an Array of CSS selector strings for elements
+ *         that should be hidden during a particular stage.
+ * }
+ *
+ * DEFAULT_TOGGLE_STYLES is the set of styles for the default variation of the
+ * toggle.
+ */
+const DEFAULT_TOGGLE_STYLES = {
+  rootID: "pictureInPictureToggle",
+  stages: {
+    hoverVideo: {
+      opacities: {
+        ".pip-wrapper": DEFAULT_TOGGLE_OPACITY,
+      },
+      hidden: [".pip-expanded"],
+    },
+
+    hoverToggle: {
+      opacities: {
+        ".pip-wrapper": 1.0,
+      },
+      hidden: [".pip-expanded"],
+    },
+  },
+};
+
+/**
+ * Given a browser and the ID for a <video> element, triggers
+ * Picture-in-Picture for that <video>, and resolves with the
+ * Picture-in-Picture window once it is ready to be used.
+ *
+ * If triggerFn is not specified, then open using the
+ * MozTogglePictureInPicture event.
+ *
+ * @param {Element,BrowsingContext} browser The <xul:browser> or
+ * BrowsingContext hosting the <video>
+ *
+ * @param {String} videoID The ID of the video to trigger
+ * Picture-in-Picture on.
+ *
+ * @param {boolean} triggerFn Use the given function to open the pip window,
+ *                  which runs in the parent process.
+ *
+ * @return Promise
+ * @resolves With the Picture-in-Picture window when ready.
+ */
+async function triggerPictureInPicture(browser, videoID, triggerFn) {
+  let domWindowOpened = BrowserTestUtils.domWindowOpenedAndLoaded(null);
+
+  let videoReady = null;
+  if (triggerFn) {
+    await SpecialPowers.spawn(browser, [videoID], async videoID => {
+      let video = content.document.getElementById(videoID);
+      video.focus();
+    });
+
+    triggerFn();
+
+    videoReady = SpecialPowers.spawn(browser, [videoID], async videoID => {
+      let video = content.document.getElementById(videoID);
+      await ContentTaskUtils.waitForCondition(() => {
+        return video.isCloningElementVisually;
+      }, "Video is being cloned visually.");
+    });
+  } else {
+    videoReady = SpecialPowers.spawn(browser, [videoID], async videoID => {
+      let video = content.document.getElementById(videoID);
+      let event = new content.CustomEvent("MozTogglePictureInPicture", {
+        bubbles: true,
+      });
+      video.dispatchEvent(event);
+      await ContentTaskUtils.waitForCondition(() => {
+        return video.isCloningElementVisually;
+      }, "Video is being cloned visually.");
+    });
+  }
+  let win = await domWindowOpened;
+  await Promise.all([
+    SimpleTest.promiseFocus(win),
+    win.promiseDocumentFlushed(() => {}),
+    videoReady,
+  ]);
+  return win;
+}
+
+/**
+ * Given a browser and the ID for a <video> element, checks that the
+ * video is showing the "This video is playing in Picture-in-Picture mode."
+ * status message overlay.
+ *
+ * @param {Element,BrowsingContext} browser The <xul:browser> or
+ * BrowsingContext hosting the <video>
+ *
+ * @param {String} videoID The ID of the video to trigger
+ * Picture-in-Picture on.
+ *
+ * @param {bool} expected True if we expect the message to be showing.
+ *
+ * @return Promise
+ * @resolves When the checks have completed.
+ */
+async function assertShowingMessage(browser, videoID, expected) {
+  let showing = await SpecialPowers.spawn(browser, [videoID], async videoID => {
+    let video = content.document.getElementById(videoID);
+    let shadowRoot = video.openOrClosedShadowRoot;
+    let pipOverlay = shadowRoot.querySelector(".pictureInPictureOverlay");
+    Assert.ok(pipOverlay, "Should be able to find Picture-in-Picture overlay.");
+
+    let rect = pipOverlay.getBoundingClientRect();
+    return rect.height > 0 && rect.width > 0;
+  });
+  Assert.equal(
+    showing,
+    expected,
+    "Video should be showing the expected state."
+  );
+}
+
+/**
+ * Tests if a video is currently being cloned for a given content browser. Provides a
+ * good indicator for answering if this video is currently open in PiP.
+ *
+ * @param {Browser} browser
+ *   The content browser or browsing contect that the video lives in
+ * @param {string} videoId
+ *   The id associated with the video
+ *
+ * @returns {bool}
+ *   Whether the video is currently being cloned (And is most likely open in PiP)
+ */
+function assertVideoIsBeingCloned(browser, selector) {
+  return SpecialPowers.spawn(browser, [selector], async slctr => {
+    let video = content.document.querySelector(slctr);
+    await ContentTaskUtils.waitForCondition(() => {
+      return video.isCloningElementVisually;
+    }, "Video is being cloned visually.");
+  });
+}
+
+/**
+ * Ensures that each of the videos loaded inside of a document in a
+ * <browser> have reached the HAVE_ENOUGH_DATA readyState.
+ *
+ * @param {Element} browser The <xul:browser> hosting the <video>(s) or the browsing context
+ *
+ * @return Promise
+ * @resolves When each <video> is in the HAVE_ENOUGH_DATA readyState.
+ */
+async function ensureVideosReady(browser) {
+  // PictureInPictureToggleChild waits for videos to fire their "canplay"
+  // event before considering them for the toggle, so we start by making
+  // sure each <video> has done this.
+  info(`Waiting for videos to be ready`);
+  await SpecialPowers.spawn(browser, [], async () => {
+    let videos = this.content.document.querySelectorAll("video");
+    for (let video of videos) {
+      video.currentTime = 0;
+      if (video.readyState < content.HTMLMediaElement.HAVE_ENOUGH_DATA) {
+        info(`Waiting for 'canplaythrough' for '${video.id}'`);
+        await ContentTaskUtils.waitForEvent(video, "canplaythrough");
+      }
+    }
+  });
+}
+
+/**
+ * Tests that the toggle opacity reaches or exceeds a certain threshold within
+ * a reasonable time.
+ *
+ * @param {Element} browser The <xul:browser> that has the <video> in it.
+ * @param {String} videoID The ID of the video element that we expect the toggle
+ * to appear on.
+ * @param {String} stage The stage for which the opacity is going to change. This
+ * should be one of "hoverVideo" or "hoverToggle".
+ * @param {Object} toggleStyles Optional argument. See the documentation for the
+ * DEFAULT_TOGGLE_STYLES object for a sense of what styleRules is expected to be.
+ *
+ * @return Promise
+ * @resolves When the check has completed.
+ */
+async function toggleOpacityReachesThreshold(
+  browser,
+  videoID,
+  stage,
+  toggleStyles = DEFAULT_TOGGLE_STYLES
+) {
+  let togglePosition = Services.prefs.getStringPref(
+    TOGGLE_POSITION_PREF,
+    "right"
+  );
+  let hasUsed = Services.prefs.getBoolPref(HAS_USED_PREF, false);
+  let toggleStylesForStage = toggleStyles.stages[stage];
+  info(
+    `Testing toggle for stage ${stage} ` +
+      `in position ${togglePosition}, has used: ${hasUsed}`
+  );
+
+  let args = { videoID, toggleStylesForStage, togglePosition, hasUsed };
+  await SpecialPowers.spawn(browser, [args], async args => {
+    let { videoID, toggleStylesForStage } = args;
+
+    let video = content.document.getElementById(videoID);
+    let shadowRoot = video.openOrClosedShadowRoot;
+
+    for (let hiddenElement of toggleStylesForStage.hidden) {
+      let el = shadowRoot.querySelector(hiddenElement);
+      ok(
+        ContentTaskUtils.is_hidden(el),
+        `Expected ${hiddenElement} to be hidden.`
+      );
+    }
+
+    for (let opacityElement in toggleStylesForStage.opacities) {
+      let opacityThreshold = toggleStylesForStage.opacities[opacityElement];
+      let el = shadowRoot.querySelector(opacityElement);
+
+      await ContentTaskUtils.waitForCondition(
+        () => {
+          let opacity = parseFloat(this.content.getComputedStyle(el).opacity);
+          return opacity >= opacityThreshold;
+        },
+        `Toggle element ${opacityElement} should have eventually reached ` +
+          `target opacity ${opacityThreshold}`,
+        100,
+        100
+      );
+    }
+
+    ok(true, "Toggle reached target opacity.");
+  });
+}
+
+/**
+ * Tests that the toggle has the correct policy attribute set. This should be called
+ * either when the toggle is visible, or events have been queued such that the toggle
+ * will soon be visible.
+ *
+ * @param {Element} browser The <xul:browser> that has the <video> in it.
+ * @param {String} videoID The ID of the video element that we expect the toggle
+ * to appear on.
+ * @param {Number} policy Optional argument. If policy is defined, then it should
+ * be one of the values in the TOGGLE_POLICIES from PictureInPictureControls.sys.mjs.
+ * If undefined, this function will ensure no policy attribute is set.
+ *
+ * @return Promise
+ * @resolves When the check has completed.
+ */
+async function assertTogglePolicy(
+  browser,
+  videoID,
+  policy,
+  toggleStyles = DEFAULT_TOGGLE_STYLES
+) {
+  let toggleID = toggleStyles.rootID;
+  let args = { videoID, toggleID, policy };
+  await SpecialPowers.spawn(browser, [args], async args => {
+    let { videoID, toggleID, policy } = args;
+
+    let video = content.document.getElementById(videoID);
+    let shadowRoot = video.openOrClosedShadowRoot;
+    let controlsOverlay = shadowRoot.querySelector(".controlsOverlay");
+    let toggle = shadowRoot.getElementById(toggleID);
+
+    await ContentTaskUtils.waitForCondition(() => {
+      return controlsOverlay.classList.contains("hovering");
+    }, "Waiting for the hovering state to be set on the video.");
+
+    if (policy) {
+      const { TOGGLE_POLICY_STRINGS } = ChromeUtils.importESModule(
+        "resource://gre/modules/PictureInPictureControls.sys.mjs"
+      );
+      let policyAttr = toggle.getAttribute("policy");
+      Assert.equal(
+        policyAttr,
+        TOGGLE_POLICY_STRINGS[policy],
+        "The correct toggle policy is set."
+      );
+    } else {
+      Assert.ok(
+        !toggle.hasAttribute("policy"),
+        "No toggle policy should be set."
+      );
+    }
+  });
+}
+
+/**
+ * Tests that either all or none of the expected mousebutton events
+ * fire in web content when clicking on the page.
+ *
+ * Note: This function will only work on pages that load the
+ * click-event-helper.js script.
+ *
+ * @param {Element} browser The <xul:browser> that will receive the mouse
+ * events.
+ * @param {bool} isExpectingEvents True if we expect all of the normal
+ * mouse button events to fire. False if we expect none of them to fire.
+ * @param {bool} isExpectingClick True if the mouse events should include the
+ * "click" event, which is only included when the primary mouse button is pressed.
+ * @return Promise
+ * @resolves When the check has completed.
+ */
+async function assertSawMouseEvents(
+  browser,
+  isExpectingEvents,
+  isExpectingClick = true
+) {
+  const MOUSE_BUTTON_EVENTS = [
+    "pointerdown",
+    "mousedown",
+    "pointerup",
+    "mouseup",
+  ];
+
+  if (isExpectingClick) {
+    MOUSE_BUTTON_EVENTS.push("click");
+  }
+
+  let mouseEvents = await SpecialPowers.spawn(browser, [], async () => {
+    return this.content.wrappedJSObject.getRecordedEvents();
+  });
+
+  let expectedEvents = isExpectingEvents ? MOUSE_BUTTON_EVENTS : [];
+  Assert.deepEqual(
+    mouseEvents,
+    expectedEvents,
+    "Expected to get the right mouse events."
+  );
+}
+
+/**
+ * Ensures that a <video> inside of a <browser> is scrolled into view,
+ * and then returns the coordinates of its Picture-in-Picture toggle as well
+ * as whether or not the <video> element is showing the built-in controls.
+ *
+ * @param {Element} browser The <xul:browser> that has the <video> loaded in it.
+ * @param {String} videoID The ID of the video that has the toggle.
+ *
+ * @return Promise
+ * @resolves With the following Object structure:
+ *   {
+ *     controls: <Boolean>,
+ *   }
+ *
+ * Where controls represents whether or not the video has the default control set
+ * displayed.
+ */
+async function prepareForToggleClick(browser, videoID) {
+  // Synthesize a mouse move just outside of the video to ensure that
+  // the video is in a non-hovering state. We'll go 5 pixels to the
+  // left and above the top-left corner.
+  await BrowserTestUtils.synthesizeMouse(
+    `#${videoID}`,
+    -5,
+    -5,
+    {
+      type: "mousemove",
+    },
+    browser,
+    false
+  );
+
+  // For each video, make sure it's scrolled into view, and get the rect for
+  // the toggle while we're at it.
+  let args = { videoID };
+  return SpecialPowers.spawn(browser, [args], async args => {
+    let { videoID } = args;
+
+    let video = content.document.getElementById(videoID);
+    video.scrollIntoView({ behaviour: "instant" });
+
+    if (!video.controls) {
+      // For no-controls <video> elements, an IntersectionObserver is used
+      // to know when we the PictureInPictureChild should begin tracking
+      // mousemove events. We don't exactly know when that IntersectionObserver
+      // will fire, so we poll a special testing function that will tell us when
+      // the video that we care about is being tracked.
+      let { PictureInPictureToggleChild } = ChromeUtils.importESModule(
+        "resource://gre/actors/PictureInPictureChild.sys.mjs"
+      );
+      await ContentTaskUtils.waitForCondition(
+        () => {
+          return PictureInPictureToggleChild.isTracking(video);
+        },
+        "Waiting for PictureInPictureToggleChild to be tracking the video.",
+        100,
+        100
+      );
+    }
+
+    let shadowRoot = video.openOrClosedShadowRoot;
+    let controlsOverlay = shadowRoot.querySelector(".controlsOverlay");
+    await ContentTaskUtils.waitForCondition(
+      () => {
+        return !controlsOverlay.classList.contains("hovering");
+      },
+      "Waiting for the video to not be hovered.",
+      100,
+      100
+    );
+
+    return {
+      controls: video.controls,
+    };
+  });
+}
+
+/**
+ * Returns client rect info for the toggle if it's supposed to be visible
+ * on hover. Otherwise, returns client rect info for the video with the
+ * associated ID.
+ *
+ * @param {Element} browser The <xul:browser> that has the <video> loaded in it.
+ * @param {String} videoID The ID of the video that has the toggle.
+ *
+ * @return Promise
+ * @resolves With the following Object structure:
+ *   {
+ *     top: <Number>,
+ *     left: <Number>,
+ *     width: <Number>,
+ *     height: <Number>,
+ *   }
+ */
+async function getToggleClientRect(
+  browser,
+  videoID,
+  toggleStyles = DEFAULT_TOGGLE_STYLES
+) {
+  let args = { videoID, toggleID: toggleStyles.rootID };
+  return ContentTask.spawn(browser, args, async args => {
+    const { Rect } = ChromeUtils.importESModule(
+      "resource://gre/modules/Geometry.sys.mjs"
+    );
+
+    let { videoID, toggleID } = args;
+    let video = content.document.getElementById(videoID);
+    let shadowRoot = video.openOrClosedShadowRoot;
+    let toggle = shadowRoot.getElementById(toggleID);
+    let rect = Rect.fromRect(toggle.getBoundingClientRect());
+
+    let clickableChildren = toggle.querySelectorAll(".clickable");
+    for (let child of clickableChildren) {
+      let childRect = Rect.fromRect(child.getBoundingClientRect());
+      rect.expandToContain(childRect);
+    }
+
+    if (!rect.width && !rect.height) {
+      rect = video.getBoundingClientRect();
+    }
+
+    return {
+      top: rect.top,
+      left: rect.left,
+      width: rect.width,
+      height: rect.height,
+    };
+  });
+}
+
+/**
+ * This function will hover over the middle of the video and then
+ * hover over the toggle.
+ * @param browser The current browser
+ * @param videoID The video element id
+ */
+async function hoverToggle(browser, videoID) {
+  await prepareForToggleClick(browser, videoID);
+
+  // Hover the mouse over the video to reveal the toggle.
+  await BrowserTestUtils.synthesizeMouseAtCenter(
+    `#${videoID}`,
+    {
+      type: "mousemove",
+    },
+    browser
+  );
+  await BrowserTestUtils.synthesizeMouseAtCenter(
+    `#${videoID}`,
+    {
+      type: "mouseover",
+    },
+    browser
+  );
+
+  info("Checking toggle policy");
+  await assertTogglePolicy(browser, videoID, null);
+
+  let toggleClientRect = await getToggleClientRect(browser, videoID);
+
+  info("Hovering the toggle rect now.");
+  let toggleCenterX = toggleClientRect.left + toggleClientRect.width / 2;
+  let toggleCenterY = toggleClientRect.top + toggleClientRect.height / 2;
+
+  await BrowserTestUtils.synthesizeMouseAtPoint(
+    toggleCenterX,
+    toggleCenterY,
+    {
+      type: "mousemove",
+    },
+    browser
+  );
+  await BrowserTestUtils.synthesizeMouseAtPoint(
+    toggleCenterX,
+    toggleCenterY,
+    {
+      type: "mouseover",
+    },
+    browser
+  );
+}
+
+/**
+ * Test helper for the Picture-in-Picture toggle. Loads a page, and then
+ * tests the provided video elements for the toggle both appearing and
+ * opening the Picture-in-Picture window in the expected cases.
+ *
+ * @param {String} testURL The URL of the page with the <video> elements.
+ * @param {Object} expectations An object with the following schema:
+ *   <video-element-id>: {
+ *     canToggle: {Boolean}
+ *     policy: {Number} (optional)
+ *     styleRules: {Object} (optional)
+ *   }
+ * If canToggle is true, then it's expected that moving the mouse over the
+ * video and then clicking in the toggle region should open a
+ * Picture-in-Picture window. If canToggle is false, we expect that a click
+ * in this region will not result in the window opening.
+ *
+ * If policy is defined, then it should be one of the values in the
+ * TOGGLE_POLICIES from PictureInPictureControls.sys.mjs.
+ *
+ * See the documentation for the DEFAULT_TOGGLE_STYLES object for a sense
+ * of what styleRules is expected to be. If left undefined, styleRules will
+ * default to DEFAULT_TOGGLE_STYLES.
+ *
+ * @param {async Function} prepFn An optional asynchronous function to run
+ * before running the toggle test. The function is passed the opened
+ * <xul:browser> as its only argument once the testURL has finished loading.
+ *
+ * @return Promise
+ * @resolves When the test is complete and the tab with the loaded page is
+ * removed.
+ */
+async function testToggle(testURL, expectations, prepFn = async () => {}) {
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: testURL,
+    },
+    async browser => {
+      await prepFn(browser);
+      await ensureVideosReady(browser);
+
+      for (let [videoID, { canToggle, policy, toggleStyles }] of Object.entries(
+        expectations
+      )) {
+        await SimpleTest.promiseFocus(browser);
+        info(`Testing video with id: ${videoID}`);
+
+        await testToggleHelper(
+          browser,
+          videoID,
+          canToggle,
+          policy,
+          toggleStyles
+        );
+      }
+    }
+  );
+}
+
+/**
+ * Test helper for the Picture-in-Picture toggle. Given a loaded page with some
+ * videos on it, tests that the toggle behaves as expected when interacted
+ * with by the mouse.
+ *
+ * @param {Element} browser The <xul:browser> that has the <video> loaded in it.
+ * @param {String} videoID The ID of the video that has the toggle.
+ * @param {Boolean} canToggle True if we expect the toggle to be visible and
+ * clickable by the mouse for the associated video.
+ * @param {Number} policy Optional argument. If policy is defined, then it should
+ * be one of the values in the TOGGLE_POLICIES from PictureInPictureControls.sys.mjs.
+ * @param {Object} toggleStyles Optional argument. See the documentation for the
+ * DEFAULT_TOGGLE_STYLES object for a sense of what styleRules is expected to be.
+ *
+ * @return Promise
+ * @resolves When the check for the toggle is complete.
+ */
+async function testToggleHelper(
+  browser,
+  videoID,
+  canToggle,
+  policy,
+  toggleStyles
+) {
+  let { controls } = await prepareForToggleClick(browser, videoID);
+
+  // Hover the mouse over the video to reveal the toggle.
+  await BrowserTestUtils.synthesizeMouseAtCenter(
+    `#${videoID}`,
+    {
+      type: "mousemove",
+    },
+    browser
+  );
+  await BrowserTestUtils.synthesizeMouseAtCenter(
+    `#${videoID}`,
+    {
+      type: "mouseover",
+    },
+    browser
+  );
+
+  info("Checking toggle policy");
+  await assertTogglePolicy(browser, videoID, policy, toggleStyles);
+
+  if (canToggle) {
+    info("Waiting for toggle to become visible");
+    await toggleOpacityReachesThreshold(
+      browser,
+      videoID,
+      "hoverVideo",
+      toggleStyles
+    );
+  }
+
+  let toggleClientRect = await getToggleClientRect(
+    browser,
+    videoID,
+    toggleStyles
+  );
+
+  info("Hovering the toggle rect now.");
+  let toggleCenterX = toggleClientRect.left + toggleClientRect.width / 2;
+  let toggleCenterY = toggleClientRect.top + toggleClientRect.height / 2;
+
+  await BrowserTestUtils.synthesizeMouseAtPoint(
+    toggleCenterX,
+    toggleCenterY,
+    {
+      type: "mousemove",
+    },
+    browser
+  );
+  await BrowserTestUtils.synthesizeMouseAtPoint(
+    toggleCenterX,
+    toggleCenterY,
+    {
+      type: "mouseover",
+    },
+    browser
+  );
+
+  if (canToggle) {
+    info("Waiting for toggle to reach full opacity");
+    await toggleOpacityReachesThreshold(
+      browser,
+      videoID,
+      "hoverToggle",
+      toggleStyles
+    );
+  }
+
+  // First, ensure that a non-primary mouse click is ignored.
+  info("Right-clicking on toggle.");
+
+  await BrowserTestUtils.synthesizeMouseAtPoint(
+    toggleCenterX,
+    toggleCenterY,
+    { button: 2 },
+    browser
+  );
+
+  // For videos without the built-in controls, we expect that all mouse events
+  // should have fired - otherwise, the events are all suppressed. For videos
+  // with controls, none of the events should be fired, as the controls overlay
+  // absorbs them all.
+  //
+  // Note that the right-click does not result in a "click" event firing.
+  await assertSawMouseEvents(browser, !controls, false);
+
+  // The message to open the Picture-in-Picture window would normally be sent
+  // immediately before this Promise resolved, so the window should have opened
+  // by now if it was going to happen.
+  for (let win of Services.wm.getEnumerator(WINDOW_TYPE)) {
+    if (!win.closed) {
+      ok(false, "Found a Picture-in-Picture window unexpectedly.");
+      return;
+    }
+  }
+
+  ok(true, "No Picture-in-Picture window found.");
+
+  // Okay, now test with the primary mouse button.
+
+  if (canToggle) {
+    info(
+      "Clicking on toggle, and expecting a Picture-in-Picture window to open"
+    );
+    let domWindowOpened = BrowserTestUtils.domWindowOpenedAndLoaded(null);
+    await BrowserTestUtils.synthesizeMouseAtPoint(
+      toggleCenterX,
+      toggleCenterY,
+      {},
+      browser
+    );
+    let win = await domWindowOpened;
+    ok(win, "A Picture-in-Picture window opened.");
+
+    await assertVideoIsBeingCloned(browser, "#" + videoID);
+
+    await BrowserTestUtils.closeWindow(win);
+
+    // Make sure that clicking on the toggle resulted in no mouse button events
+    // being fired in content.
+    await assertSawMouseEvents(browser, false);
+  } else {
+    info(
+      "Clicking on toggle, and expecting no Picture-in-Picture window opens"
+    );
+    await BrowserTestUtils.synthesizeMouseAtPoint(
+      toggleCenterX,
+      toggleCenterY,
+      {},
+      browser
+    );
+
+    // If we aren't showing the toggle, we expect all mouse events to be seen.
+    await assertSawMouseEvents(browser, !controls);
+
+    // The message to open the Picture-in-Picture window would normally be sent
+    // immediately before this Promise resolved, so the window should have opened
+    // by now if it was going to happen.
+    for (let win of Services.wm.getEnumerator(WINDOW_TYPE)) {
+      if (!win.closed) {
+        ok(false, "Found a Picture-in-Picture window unexpectedly.");
+        return;
+      }
+    }
+
+    ok(true, "No Picture-in-Picture window found.");
+  }
+
+  // Click on the very top-left pixel of the document and ensure that we
+  // see all of the mouse events for it.
+  await BrowserTestUtils.synthesizeMouseAtPoint(1, 1, {}, browser);
+  await assertSawMouseEvents(browser, true);
+}
+
+/**
+ * Helper function that ensures that a provided async function
+ * causes a window to fully enter fullscreen mode.
+ *
+ * @param window (DOM Window)
+ *   The window that is expected to enter fullscreen mode.
+ * @param asyncFn (Async Function)
+ *   The async function to run to trigger the fullscreen switch.
+ * @return Promise
+ * @resolves When the fullscreen entering transition completes.
+ */
+async function promiseFullscreenEntered(window, asyncFn) {
+  let entered = BrowserTestUtils.waitForEvent(
+    window,
+    "MozDOMFullscreen:Entered"
+  );
+
+  await asyncFn();
+
+  await entered;
+
+  await BrowserTestUtils.waitForCondition(() => {
+    return !TelemetryStopwatch.running("FULLSCREEN_CHANGE_MS");
+  });
+}
+
+/**
+ * Helper function that ensures that a provided async function
+ * causes a window to fully exit fullscreen mode.
+ *
+ * @param window (DOM Window)
+ *   The window that is expected to exit fullscreen mode.
+ * @param asyncFn (Async Function)
+ *   The async function to run to trigger the fullscreen switch.
+ * @return Promise
+ * @resolves When the fullscreen exiting transition completes.
+ */
+async function promiseFullscreenExited(window, asyncFn) {
+  let exited = BrowserTestUtils.waitForEvent(window, "MozDOMFullscreen:Exited");
+
+  await asyncFn();
+
+  await exited;
+
+  await BrowserTestUtils.waitForCondition(() => {
+    return !TelemetryStopwatch.running("FULLSCREEN_CHANGE_MS");
+  });
+
+  if (AppConstants.platform == "macosx") {
+    // On macOS, the fullscreen transition takes some extra time
+    // to complete, and we don't receive events for it. We need to
+    // wait for it to complete or else input events in the next test
+    // might get eaten up. This is the best we can currently do.
+    //
+    // eslint-disable-next-line mozilla/no-arbitrary-setTimeout
+    await new Promise(resolve => setTimeout(resolve, 2000));
+  }
+}
+
+/**
+ * Helper function that ensures that the "This video is
+ * playing in Picture-in-Picture mode" message works,
+ * then closes the player window
+ *
+ * @param {Element} browser The <xul:browser> that has the <video> loaded in it.
+ * @param {String} videoID The ID of the video that has the toggle.
+ * @param {Element} pipWin The Picture-in-Picture window that was opened
+ * @param {Boolean} iframe True if the test is on an Iframe, which modifies
+ * the test behavior
+ */
+async function ensureMessageAndClosePiP(browser, videoID, pipWin, isIframe) {
+  try {
+    await assertShowingMessage(browser, videoID, true);
+  } finally {
+    let uaWidgetUpdate = null;
+    if (isIframe) {
+      uaWidgetUpdate = SpecialPowers.spawn(browser, [], async () => {
+        await ContentTaskUtils.waitForEvent(
+          content.windowRoot,
+          "UAWidgetSetupOrChange",
+          true /* capture */
+        );
+      });
+    } else {
+      uaWidgetUpdate = BrowserTestUtils.waitForContentEvent(
+        browser,
+        "UAWidgetSetupOrChange",
+        true /* capture */
+      );
+    }
+    await BrowserTestUtils.closeWindow(pipWin);
+    await uaWidgetUpdate;
+  }
+}
+
+/**
+ * Helper function that returns True if the specified video is paused
+ * and False if the specified video is not paused.
+ *
+ * @param {Element} browser The <xul:browser> that has the <video> loaded in it.
+ * @param {String} videoID The ID of the video to check.
+ */
+async function isVideoPaused(browser, videoID) {
+  return SpecialPowers.spawn(browser, [videoID], async videoID => {
+    return content.document.getElementById(videoID).paused;
+  });
+}
+
+/**
+ * Helper function that returns True if the specified video is muted
+ * and False if the specified video is not muted.
+ *
+ * @param {Element} browser The <xul:browser> that has the <video> loaded in it.
+ * @param {String} videoID The ID of the video to check.
+ */
+async function isVideoMuted(browser, videoID) {
+  return SpecialPowers.spawn(browser, [videoID], async videoID => {
+    return content.document.getElementById(videoID).muted;
+  });
+}
+
+/**
+ * Initializes videos and text tracks for the current test case.
+ * First track is the default track to be loaded onto the video.
+ * Once initialization is done, play then pause the requested video.
+ * so that text tracks are loaded.
+ * @param {Element} browser The <xul:browser> hosting the <video>
+ * @param {String} videoID The ID of the video being checked
+ * @param {Integer} defaultTrackIndex The index of the track to be loaded, or none if -1
+ * @param {String} trackMode the mode that the video's textTracks should be set to
+ */
+async function prepareVideosAndWebVTTTracks(
+  browser,
+  videoID,
+  defaultTrackIndex = 0,
+  trackMode = "showing"
+) {
+  info("Preparing video and initial text tracks");
+  await ensureVideosReady(browser);
+  await SpecialPowers.spawn(
+    browser,
+    [{ videoID, defaultTrackIndex, trackMode }],
+    async args => {
+      let video = content.document.getElementById(args.videoID);
+      let tracks = video.textTracks;
+
+      is(tracks.length, 5, "Number of tracks loaded should be 5");
+
+      // Enable track for originating video
+      if (args.defaultTrackIndex >= 0) {
+        info(`Loading track ${args.defaultTrackIndex + 1}`);
+        let track = tracks[args.defaultTrackIndex];
+        tracks.mode = args.trackMode;
+        track.mode = args.trackMode;
+      }
+
+      // Briefly play the video to load text tracks onto the pip window.
+      info("Playing video to load text tracks");
+      video.play();
+      info("Pausing video");
+      video.pause();
+      ok(video.paused, "Video should be paused before proceeding with test");
+    }
+  );
+}
+
+/**
+ * Plays originating video until the next cue is loaded.
+ * Once the next cue is loaded, pause the video.
+ * @param {Element} browser The <xul:browser> hosting the <video>
+ * @param {String} videoID The ID of the video being checked
+ * @param {Integer} textTrackIndex The index of the track to be loaded, or none if -1
+ */
+async function waitForNextCue(browser, videoID, textTrackIndex = 0) {
+  if (textTrackIndex < 0) {
+    ok(false, "Cannot wait for next cue with invalid track index");
+  }
+
+  await SpecialPowers.spawn(
+    browser,
+    [{ videoID, textTrackIndex }],
+    async args => {
+      let video = content.document.getElementById(args.videoID);
+      info("Playing video to activate next cue");
+      video.play();
+      ok(!video.paused, "Video is playing");
+
+      info("Waiting until cuechange is called");
+      await ContentTaskUtils.waitForEvent(
+        video.textTracks[args.textTrackIndex],
+        "cuechange"
+      );
+
+      info("Pausing video to read text track");
+      video.pause();
+      ok(video.paused, "Video is paused");
+    }
+  );
+}
+
+/**
+ * The PiP window saves the positon when closed and sometimes we don't want
+ * this information to persist to other tests. This function will clear the
+ * position so the PiP window will open in the default position.
+ */
+function clearSavedPosition() {
+  let xulStore = Services.xulStore;
+  xulStore.setValue(PLAYER_URI, "picture-in-picture", "left", NaN);
+  xulStore.setValue(PLAYER_URI, "picture-in-picture", "top", NaN);
+  xulStore.setValue(PLAYER_URI, "picture-in-picture", "width", NaN);
+  xulStore.setValue(PLAYER_URI, "picture-in-picture", "height", NaN);
+}
+
+function overrideSavedPosition(left, top, width, height) {
+  let xulStore = Services.xulStore;
+  xulStore.setValue(PLAYER_URI, "picture-in-picture", "left", left);
+  xulStore.setValue(PLAYER_URI, "picture-in-picture", "top", top);
+  xulStore.setValue(PLAYER_URI, "picture-in-picture", "width", width);
+  xulStore.setValue(PLAYER_URI, "picture-in-picture", "height", height);
+}
+
+/**
+ * Function used to filter events when waiting for the correct number
+ * telemetry events.
+ * @param {String} expected The expected string or undefined
+ * @param {String} actual The actual string
+ * @returns true if the expected is undefined or if expected matches actual
+ */
+function matches(expected, actual) {
+  if (expected === undefined) {
+    return true;
+  }
+  return expected === actual;
+}
+
+/**
+ * Function that waits for the expected number of events aftering filtering.
+ * @param {Object} filter An object containing optional filters
+ *  {
+ *    category: (optional) The category of the event. Ex. "pictureinpicture"
+ *    method: (optional) The method of the event. Ex. "create"
+ *    object: (optional) The object of the event. Ex. "player"
+ *  }
+ * @param {Number} length The number of events to wait for
+ * @param {String} process Should be "content" or "parent" depending on the event
+ */
+async function waitForTelemeryEvents(filter, length, process) {
+  let {
+    category: filterCategory,
+    method: filterMethod,
+    object: filterObject,
+  } = filter;
+
+  let events = [];
+  await TestUtils.waitForCondition(
+    () => {
+      events = Services.telemetry.snapshotEvents(
+        Ci.nsITelemetry.DATASET_PRERELEASE_CHANNELS,
+        false
+      )[process];
+      if (!events) {
+        return false;
+      }
+
+      let filtered = events
+        .map(([, /* timestamp */ category, method, object, value, extra]) => {
+          // We don't care about the `timestamp` value.
+          // Tests that examine that value should use `snapshotEvents` directly.
+          return [category, method, object, value, extra];
+        })
+        .filter(([category, method, object]) => {
+          return (
+            matches(filterCategory, category) &&
+            matches(filterMethod, method) &&
+            matches(filterObject, object)
+          );
+        });
+      info(JSON.stringify(filtered, null, 2));
+      return filtered && filtered.length >= length;
+    },
+    `Waiting for ${length} pictureinpicture telemetry event(s) with filter ${JSON.stringify(
+      filter,
+      null,
+      2
+    )}`,
+    200,
+    100
+  );
+}
diff --git a/toolkit/components/pictureinpicture/tests/no-audio-track.webm b/toolkit/components/pictureinpicture/tests/no-audio-track.webm
new file mode 100644
index 0000000000..72b0297233
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/no-audio-track.webm
diff --git a/toolkit/components/pictureinpicture/tests/short.mp4 b/toolkit/components/pictureinpicture/tests/short.mp4
new file mode 100644
index 0000000000..abe37b9f9d
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/short.mp4
diff --git a/toolkit/components/pictureinpicture/tests/test-button-overlay.html b/toolkit/components/pictureinpicture/tests/test-button-overlay.html
new file mode 100644
index 0000000000..9917fba973
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/test-button-overlay.html
@@ -0,0 +1,81 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>Picture-in-Picture test - transparent overlays - 1</title>
+  <script type="text/javascript" src="click-event-helper.js"></script>
+</head>
+<style>
+  video {
+    display: block;
+  }
+
+  .container {
+    position: relative;
+    display: inline-block;
+  }
+
+  .overlay {
+    position: absolute;
+    left: 0;
+    top: 0;
+    width: 100%;
+    height: 100%;
+    color: white;
+  }
+
+  .toggle-overlay {
+    position: absolute;
+    min-width: 50px;
+    right: 0px;
+    height: 100%;
+    top: calc(50% - 25px);
+  }
+
+  button {
+    height: 100px;
+  }
+
+  .transparent-background {
+    background-color: transparent;
+  }
+
+  .partial-opacity {
+    opacity: 0.5;
+  }
+
+  .full-opacity {
+    opacity: 1.0;
+    background-color: green;
+  }
+
+  .no-pointer-events {
+    pointer-events: none;
+  }
+
+  .pointer-events {
+    pointer-events: auto;
+  }
+</style>
+<body>
+  <div class="container">
+    <div class="overlay transparent-background no-pointer-events">
+      This is a fully transparent overlay using a transparent background.
+      <div class="toggle-overlay partial-opacity pointer-events">
+        <button>I'm a button overlapping the toggle</button>
+      </div>
+    </div>
+    <video id="video-partial-transparent-button" src="test-video.mp4" loop="true"></video>
+  </div>
+
+  <div class="container">
+    <div class="overlay transparent-background no-pointer-events">
+      This is a fully transparent overlay using a transparent background.
+      <div class="toggle-overlay full-opacity pointer-events">
+        <button>I'm a button overlapping the toggle</button>
+      </div>
+    </div>
+    <video id="video-opaque-button" src="test-video.mp4" loop="true"></video>
+  </div>
+</body>
+</html>
diff --git a/toolkit/components/pictureinpicture/tests/test-media-stream.html b/toolkit/components/pictureinpicture/tests/test-media-stream.html
new file mode 100644
index 0000000000..ad5f91dd25
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/test-media-stream.html
@@ -0,0 +1,25 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>Picture-in-Picture tests</title>
+  <script type="text/javascript" src="click-event-helper.js"></script>
+</head>
+<style>
+  video {
+    display: block;
+    border: 1px solid black;
+  }
+</style>
+<body>
+  <script>
+    function fireEvents() {
+      for (let videoID of ["with-controls", "no-controls"]) {
+        let video = document.getElementById(videoID);
+        let event = new CustomEvent("MozTogglePictureInPicture", { bubbles: true });
+        video.dispatchEvent(event);
+      }
+    }
+  </script>
+</body>
+</html>
diff --git a/toolkit/components/pictureinpicture/tests/test-opaque-overlay.html b/toolkit/components/pictureinpicture/tests/test-opaque-overlay.html
new file mode 100644
index 0000000000..425c0e74c2
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/test-opaque-overlay.html
@@ -0,0 +1,51 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>Picture-in-Picture test - transparent overlays - 1</title>
+  <script type="text/javascript" src="click-event-helper.js"></script>
+</head>
+<style>
+  video {
+    display: block;
+  }
+
+  .container {
+    position: relative;
+    display: inline-block;
+  }
+
+  .overlay {
+    position: absolute;
+    left: 0;
+    top: 0;
+    width: 100%;
+    height: 100%;
+    color: white;
+  }
+
+  .toggle-overlay {
+    position: absolute;
+    min-width: 50px;
+    right: 0px;
+    height: 100%;
+    top: calc(50% - 25px);
+  }
+
+  .full-opacity {
+    opacity: 1.0;
+    background-color: green;
+  }
+</style>
+<body>
+  <div class="container">
+    <div class="overlay full-opacity">This is a fully opaque overlay using opacity: 1.0</div>
+    <video id="video-full-opacity" src="test-video.mp4" loop="true"></video>
+  </div>
+
+  <div class="container">
+    <div class="toggle-overlay full-opacity">This is a fully opaque overlay over a region covering the toggle at opacity: 1.0</div>
+    <video id="video-full-opacity-over-toggle" src="test-video.mp4" loop="true"></video>
+  </div>
+</body>
+</html>
diff --git a/toolkit/components/pictureinpicture/tests/test-page-multiple-contexts.html b/toolkit/components/pictureinpicture/tests/test-page-multiple-contexts.html
new file mode 100644
index 0000000000..420370aff2
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/test-page-multiple-contexts.html
@@ -0,0 +1,19 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>Picture-in-Picture tests</title>
+</head>
+<style>
+  video {
+    display: block;
+    border: 1px solid black;
+  }
+</style>
+<body>
+  <h1>Video in page</h1>
+  <video id="with-controls" src="test-video.mp4" controls loop="true" width="400" height="225"></video>
+  <h1>Video in frame</h1>
+  <iframe id="iframe" width="400" height="225" src="test-video.mp4"></iframe>
+</body>
+</html>
diff --git a/toolkit/components/pictureinpicture/tests/test-page-pipDisabled.html b/toolkit/components/pictureinpicture/tests/test-page-pipDisabled.html
new file mode 100644
index 0000000000..142d2d74d2
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/test-page-pipDisabled.html
@@ -0,0 +1,18 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>Picture-in-Picture tests</title>
+  <script type="text/javascript" src="click-event-helper.js"></script>
+</head>
+<style>
+  video {
+    display: block;
+    border: 1px solid black;
+  }
+</style>
+<body>
+  <h1>Video with PiPDisabled</h1>
+  <video id="with-controls" src="test-video.mp4" controls loop="true" width="400" height="225" disablePictureInPicture="true"></video>
+</body>
+</html>
diff --git a/toolkit/components/pictureinpicture/tests/test-page-with-iframe.html b/toolkit/components/pictureinpicture/tests/test-page-with-iframe.html
new file mode 100644
index 0000000000..02205a028b
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/test-page-with-iframe.html
@@ -0,0 +1,27 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>Picture-in-Picture tests</title>
+  <script type="text/javascript" src="click-event-helper.js"></script>
+</head>
+<style>
+  html, body {
+    height: 100vh;
+    width: 100vw;
+    margin: 0;
+    padding: 0;
+    overflow: hidden;
+  }
+  #iframe {
+    height: 100vh;
+    width: 100vw;
+    padding: 0;
+    margin: 0;
+    border: 0;
+  }
+</style>
+<body>
+  <iframe id="iframe"></iframe>
+</body>
+</html>
diff --git a/toolkit/components/pictureinpicture/tests/test-page-with-nan-video-duration.html b/toolkit/components/pictureinpicture/tests/test-page-with-nan-video-duration.html
new file mode 100644
index 0000000000..b16c3682a0
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/test-page-with-nan-video-duration.html
@@ -0,0 +1,14 @@
+<!DOCTYPE html>
+<html>
+  <head>
+    <meta charset="utf-8">
+    <title>Bug 1679174</title>
+    <script type="text/javascript" src="click-event-helper.js"></script>
+  </head>
+  <body>
+    <video id="nan-duration"></video>
+    <video controls id="test-video">
+      <source src="test-video.mp4" type="video/mp4">
+    </video>
+  </body>
+</html>
diff --git a/toolkit/components/pictureinpicture/tests/test-page-with-sound.html b/toolkit/components/pictureinpicture/tests/test-page-with-sound.html
new file mode 100644
index 0000000000..6b6a860bc2
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/test-page-with-sound.html
@@ -0,0 +1,20 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>Picture-in-Picture tests (longer video with sound)</title>
+  <script type="text/javascript" src="click-event-helper.js"></script>
+</head>
+<style>
+  video {
+    display: block;
+    border: 1px solid black;
+  }
+</style>
+<body>
+  <h1>Video with controls</h1>
+  <video id="with-controls" src="gizmo.mp4" controls loop="true"></video>
+  <h1>Video without controls</h1>
+  <video id="no-controls" src="gizmo.mp4" loop="true"></video>
+</body>
+</html>
diff --git a/toolkit/components/pictureinpicture/tests/test-page-with-webvtt.html b/toolkit/components/pictureinpicture/tests/test-page-with-webvtt.html
new file mode 100644
index 0000000000..e05ad8dd2c
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/test-page-with-webvtt.html
@@ -0,0 +1,66 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>Picture-in-Picture tests</title>
+  <script type="text/javascript" src="click-event-helper.js"></script>
+</head>
+<style>
+  video {
+    display: block;
+    border: 1px solid black;
+  }
+</style>
+<body>
+  <h1>Video with controls</h1>
+  <video id="with-controls" src="test-video-long.mp4" controls width="400" height="225">
+    <track
+      id="track1"
+      kind="captions"
+      label="[test] en"
+      srclang="en"
+      src="test-webvtt-1.vtt"
+    />
+    <track
+    id="track2"
+    kind="subtitles"
+    label="[test] fr"
+    srclang="fr"
+    src="test-webvtt-2.vtt"
+    />
+    <track
+    id="track3"
+    kind="subtitles"
+    label="[test] eo"
+    srclang="eo"
+    src="test-webvtt-3.vtt"
+    />
+    <track
+    id="track4"
+    kind="subtitles"
+    label="[test] zh"
+    srclang="zh"
+    src="test-webvtt-4.vtt"
+    />
+    <track
+    id="track5"
+    kind="subtitles"
+    label="[test] es"
+    srclang="es"
+    src="test-webvtt-5.vtt"
+    />
+  </video>
+
+  <video id="with-controls-no-tracks" src="test-video-long.mp4" controls width="400" height="225"></video>
+
+  <script>
+    function fireEvents() {
+      for (let videoID of ["with-controls"]) {
+        let video = document.getElementById(videoID);
+        let event = new CustomEvent("MozTogglePictureInPicture", { bubbles: true });
+        video.dispatchEvent(event);
+      }
+    }
+  </script>
+</body>
+</html>
diff --git a/toolkit/components/pictureinpicture/tests/test-page-without-audio.html b/toolkit/components/pictureinpicture/tests/test-page-without-audio.html
new file mode 100644
index 0000000000..862042cd59
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/test-page-without-audio.html
@@ -0,0 +1,18 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>Picture-in-Picture tests</title>
+  <script type="text/javascript" src="click-event-helper.js"></script>
+</head>
+<style>
+  video {
+    display: block;
+    border: 1px solid black;
+  }
+</style>
+<body>
+  <h1>Video without audio track</h1>
+  <video id="without-audio" src="no-audio-track.webm" controls width="400" height="225"></video>
+</body>
+</html>
diff --git a/toolkit/components/pictureinpicture/tests/test-page.html b/toolkit/components/pictureinpicture/tests/test-page.html
new file mode 100644
index 0000000000..a62ff1ac4a
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/test-page.html
@@ -0,0 +1,30 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>Picture-in-Picture tests</title>
+  <script type="text/javascript" src="click-event-helper.js"></script>
+</head>
+<style>
+  video {
+    display: block;
+    border: 1px solid black;
+  }
+</style>
+<body>
+  <h1>Video with controls</h1>
+  <video id="with-controls" src="test-video.mp4" controls loop="true" width="400" height="225"></video>
+  <h1>Video without controls</h1>
+  <video id="no-controls" src="test-video.mp4" loop="true" width="400" height="225"></video>
+
+  <script>
+    function fireEvents() {
+      for (let videoID of ["with-controls", "no-controls"]) {
+        let video = document.getElementById(videoID);
+        let event = new CustomEvent("MozTogglePictureInPicture", { bubbles: true });
+        video.dispatchEvent(event);
+      }
+    }
+  </script>
+</body>
+</html>
diff --git a/toolkit/components/pictureinpicture/tests/test-pointer-events-none.html b/toolkit/components/pictureinpicture/tests/test-pointer-events-none.html
new file mode 100644
index 0000000000..63254b329c
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/test-pointer-events-none.html
@@ -0,0 +1,21 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>Picture-in-Picture test - pointer-events: none</title>
+  <script type="text/javascript" src="click-event-helper.js"></script>
+</head>
+<style>
+  video {
+    display: block;
+    pointer-events: none;
+  }
+
+</style>
+<body>
+  <h1>Video with controls</h1>
+  <video id="with-controls" src="test-video.mp4" controls loop="true"></video>
+  <h1>Video without controls</h1>
+  <video id="no-controls" src="test-video.mp4" loop="true"></video>
+</body>
+</html>
diff --git a/toolkit/components/pictureinpicture/tests/test-reversed.html b/toolkit/components/pictureinpicture/tests/test-reversed.html
new file mode 100644
index 0000000000..4f6d516698
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/test-reversed.html
@@ -0,0 +1,19 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>Picture-in-Picture tests</title>
+  <script type="text/javascript" src="click-event-helper.js"></script>
+</head>
+<style>
+  #reversed {
+      transform: scaleX(-1);
+  }
+</style>
+<body>
+    <h1>Reversed video</h1>
+    <video id="reversed" src="test-video.mp4" controls loop="true" width="400" height="225"></video>
+    <h1>Not Reversed Video</h1>
+    <video id="not-reversed" src="test-video.mp4" loop="true" width="400" height="225"></video>
+</body>
+</html>
diff --git a/toolkit/components/pictureinpicture/tests/test-transparent-nested-iframes.html b/toolkit/components/pictureinpicture/tests/test-transparent-nested-iframes.html
new file mode 100644
index 0000000000..d7efcc1e92
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/test-transparent-nested-iframes.html
@@ -0,0 +1,51 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>Picture-in-Picture test - transparent iframe</title>
+</head>
+
+<style>
+  video {
+    display: block;
+  }
+
+  .root {
+    position: relative;
+    display: inline-block;
+  }
+
+  .controls {
+    position: absolute;
+    left: 0;
+    top: 0;
+    width: 100%;
+    height: 100%;
+    color: white;
+  }
+
+  .container,
+  iframe {
+    width: 100%;
+    height: 100%;
+  }
+
+  iframe {
+    border: 0;
+  }
+</style>
+
+<body>
+  <div class="root">
+    <div class="controls">
+      <div class="container">
+        <iframe src="about:blank"></iframe>
+      </div>
+    </div>
+
+    <div class="video-container">
+      <video id="video-transparent-background" src="test-video.mp4" loop="true"></video>
+    </div>
+  </div>
+</body>
+</html>
diff --git a/toolkit/components/pictureinpicture/tests/test-transparent-overlay-1.html b/toolkit/components/pictureinpicture/tests/test-transparent-overlay-1.html
new file mode 100644
index 0000000000..8f0f76311b
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/test-transparent-overlay-1.html
@@ -0,0 +1,46 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>Picture-in-Picture test - transparent overlays - 1</title>
+  <script type="text/javascript" src="click-event-helper.js"></script>
+</head>
+<style>
+  video {
+    display: block;
+  }
+
+  .container {
+    position: relative;
+    display: inline-block;
+  }
+
+  .overlay {
+    position: absolute;
+    left: 0;
+    top: 0;
+    width: 100%;
+    height: 100%;
+    color: white;
+  }
+
+  .transparent-background {
+    background-color: transparent;
+  }
+
+  .alpha-background {
+    background-color: rgba(255, 0, 0, 0.5);
+  }
+</style>
+<body>
+  <div class="container">
+    <div class="overlay transparent-background">This is a fully transparent overlay</div>
+    <video id="video-transparent-background" src="test-video.mp4" loop="true"></video>
+  </div>
+
+  <div class="container">
+    <div class="overlay alpha-background">This is a partially transparent overlay using alpha</div>
+    <video id="video-alpha-background" src="test-video.mp4" loop="true"></video>
+  </div>
+</body>
+</html>
diff --git a/toolkit/components/pictureinpicture/tests/test-transparent-overlay-2.html b/toolkit/components/pictureinpicture/tests/test-transparent-overlay-2.html
new file mode 100644
index 0000000000..86dab15690
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/test-transparent-overlay-2.html
@@ -0,0 +1,46 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>Picture-in-Picture test - transparent overlays - 1</title>
+  <script type="text/javascript" src="click-event-helper.js"></script>
+</head>
+<style>
+  video {
+    display: block;
+  }
+
+  .container {
+    position: relative;
+    display: inline-block;
+  }
+
+  .overlay {
+    position: absolute;
+    left: 0;
+    top: 0;
+    width: 100%;
+    height: 100%;
+    color: white;
+  }
+
+  .zero-opacity {
+    opacity: 0;
+  }
+
+  .partial-opacity {
+    opacity: 0.5;
+  }
+</style>
+<body>
+  <div class="container">
+    <div class="overlay zero-opacity">This is a transparent overlay using opacity: 0</div>
+    <video id="video-zero-opacity" src="test-video.mp4" loop="true"></video>
+  </div>
+
+  <div class="container">
+    <div class="overlay partial-opacity">This is a partially transparent overlay using opacity: 0.5</div>
+    <video id="video-partial-opacity" src="test-video.mp4" loop="true"></video>
+  </div>
+</body>
+</html>
diff --git a/toolkit/components/pictureinpicture/tests/test-video-cropped.mp4 b/toolkit/components/pictureinpicture/tests/test-video-cropped.mp4
new file mode 100644
index 0000000000..6ea66eb1fc
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/test-video-cropped.mp4
diff --git a/toolkit/components/pictureinpicture/tests/test-video-long.mp4 b/toolkit/components/pictureinpicture/tests/test-video-long.mp4
new file mode 100644
index 0000000000..714c17ca12
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/test-video-long.mp4
diff --git a/toolkit/components/pictureinpicture/tests/test-video-selection.html b/toolkit/components/pictureinpicture/tests/test-video-selection.html
new file mode 100644
index 0000000000..4ce65d6309
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/test-video-selection.html
@@ -0,0 +1,22 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>Picture-in-Picture tests</title>
+  <script type="text/javascript"></script>
+</head>
+<style>
+  video {
+    display: block;
+    border: 1px solid black;
+  }
+</style>
+<body>
+  <h1>Shortest Video</h1>
+  <video id="shortest" src="test-video.mp4" controls loop="true"></video>
+  <h1>Shorter Video</h1>
+  <video id="short" src="short.mp4" controls loop="true"></video>
+  <h1>Longer Video</h1>
+  <video id="long" src="test-video-long.mp4" controls loop="true"></video>
+</body>
+</html>
diff --git a/toolkit/components/pictureinpicture/tests/test-video-vertical.mp4 b/toolkit/components/pictureinpicture/tests/test-video-vertical.mp4
new file mode 100644
index 0000000000..404eec6fd0
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/test-video-vertical.mp4
diff --git a/toolkit/components/pictureinpicture/tests/test-video.mp4 b/toolkit/components/pictureinpicture/tests/test-video.mp4
new file mode 100644
index 0000000000..90bbe6bc26
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/test-video.mp4
diff --git a/toolkit/components/pictureinpicture/tests/test-webvtt-1.vtt b/toolkit/components/pictureinpicture/tests/test-webvtt-1.vtt
new file mode 100644
index 0000000000..fd16ef6d32
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/test-webvtt-1.vtt
@@ -0,0 +1,10 @@
+WEBVTT
+
+1
+00:00:00.000 --> 00:00:01.000
+track 1 - cue 1
+
+2
+00:00:02.000 --> 00:00:05.000
+- <b>track 1 - cue 2 bold</b>
+- <i>track 1 - cue 2 italicized<i>
diff --git a/toolkit/components/pictureinpicture/tests/test-webvtt-2.vtt b/toolkit/components/pictureinpicture/tests/test-webvtt-2.vtt
new file mode 100644
index 0000000000..21fda2b75c
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/test-webvtt-2.vtt
@@ -0,0 +1,10 @@
+WEBVTT
+
+1
+00:00:00.000 --> 00:00:01.000
+track 2 - cue 1
+
+2
+00:00:02.000 --> 00:00:05.000
+- <b>track 2 - cue 2 bold</b>
+- <i>track 2 - cue 2 italicized<i>
diff --git a/toolkit/components/pictureinpicture/tests/test-webvtt-3.vtt b/toolkit/components/pictureinpicture/tests/test-webvtt-3.vtt
new file mode 100644
index 0000000000..0207d9e65f
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/test-webvtt-3.vtt
@@ -0,0 +1,11 @@
+WEBVTT
+
+Test file with multiple active cues and VTTCue.line as "auto"
+
+1
+00:00:00.000 --> 00:00:01.000
+track 3 - cue 1
+
+2
+00:00:00.000 --> 00:00:01.000
+track 3 - cue 2
diff --git a/toolkit/components/pictureinpicture/tests/test-webvtt-4.vtt b/toolkit/components/pictureinpicture/tests/test-webvtt-4.vtt
new file mode 100644
index 0000000000..9e4a540f7f
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/test-webvtt-4.vtt
@@ -0,0 +1,15 @@
+WEBVTT
+
+Test file with multiple active cues and VTTCue.line as an integer
+
+1
+00:00:00.000 --> 00:00:01.000 line:2
+track 4 - cue 1 - integer line
+
+2
+00:00:00.000 --> 00:00:01.000 line:3
+track 4 - cue 2 - integer line
+
+3
+00:00:00.000 --> 00:00:01.000 line:1
+track 4 - cue 3 - integer line
diff --git a/toolkit/components/pictureinpicture/tests/test-webvtt-5.vtt b/toolkit/components/pictureinpicture/tests/test-webvtt-5.vtt
new file mode 100644
index 0000000000..3a25d83529
--- /dev/null
+++ b/toolkit/components/pictureinpicture/tests/test-webvtt-5.vtt
@@ -0,0 +1,12 @@
+WEBVTT
+
+Test file with multiple active cues and VTTCue.line as a percentage value
+
+00:00:00.000 --> 00:00:01.000 line:90%
+track 5 - cue 1 - percent line
+
+00:00:00.000 --> 00:00:01.000 line:10%
+track 5 - cue 2 - percent line
+
+00:00:00.000 --> 00:00:01.000 line:50%
+track 5 - cue 3 - percent line