Merging upstream version 125.0.1.

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

23 files changed, 393 insertions, 118 deletions

diff --git a/remote/shared/AppInfo.sys.mjs b/remote/shared/AppInfo.sys.mjs
index 9e354503ef..16db0191de 100644
--- a/remote/shared/AppInfo.sys.mjs
+++ b/remote/shared/AppInfo.sys.mjs
@@ -24,7 +24,7 @@ const ID_THUNDERBIRD = "{3550f703-e582-4d05-9a08-453d09bdfdc6}";
 export const AppInfo = new Proxy(
   {},
   {
-    get(target, prop, receiver) {
+    get(target, prop) {
       if (target.hasOwnProperty(prop)) {
         return target[prop];
       }
diff --git a/remote/shared/RecommendedPreferences.sys.mjs b/remote/shared/RecommendedPreferences.sys.mjs
index d0a7739e52..b52057ee2b 100644
--- a/remote/shared/RecommendedPreferences.sys.mjs
+++ b/remote/shared/RecommendedPreferences.sys.mjs
@@ -145,6 +145,9 @@ const COMMON_PREFERENCES = new Map([
   // Do not redirect user when a milstone upgrade of Firefox is detected
   ["browser.startup.homepage_override.mstone", "ignore"],
 
+  // Unload the previously selected tab immediately
+  ["browser.tabs.remote.unloadDelayMs", 0],
+
   // Don't unload tabs when available memory is running low
   ["browser.tabs.unloadOnLowMemory", false],
 
@@ -310,6 +313,9 @@ const COMMON_PREFERENCES = new Map([
   // Privacy and Tracking Protection
   ["privacy.trackingprotection.enabled", false],
 
+  // Used to check if recommended preferences are applied
+  ["remote.prefs.recommended.applied", true],
+
   // Don't do network connections for mitm priming
   ["security.certerrors.mitm.priming.enabled", false],
 
@@ -362,7 +368,7 @@ export const RecommendedPreferences = {
    * @param {Map<string, object>=} preferences
    *     Map of preference name to preference value.
    */
-  applyPreferences(preferences) {
+  applyPreferences(preferences = new Map()) {
     if (!lazy.useRecommendedPrefs) {
       // If remote.prefs.recommended is set to false, do not set any preference
       // here. Needed for our Firefox CI.
@@ -374,11 +380,7 @@ export const RecommendedPreferences = {
     if (!this.isInitialized) {
       // Merge common preferences and optionally provided preferences in a
       // single map. Hereby the extra preferences have higher priority.
-      if (preferences) {
-        preferences = new Map([...COMMON_PREFERENCES, ...preferences]);
-      } else {
-        preferences = COMMON_PREFERENCES;
-      }
+      preferences = new Map([...COMMON_PREFERENCES, ...preferences]);
 
       Services.obs.addObserver(this, "quit-application");
       this.isInitialized = true;
diff --git a/remote/shared/WebSocketConnection.sys.mjs b/remote/shared/WebSocketConnection.sys.mjs
index c9ef050dc5..57b533fffb 100644
--- a/remote/shared/WebSocketConnection.sys.mjs
+++ b/remote/shared/WebSocketConnection.sys.mjs
@@ -85,11 +85,8 @@ export class WebSocketConnection {
    * Register a new Session to forward the messages to.
    *
    * Needs to be implemented in the sub class.
-   *
-   * @param {Session} session
-   *     The session to register.
    */
-  registerSession(session) {
+  registerSession() {
     throw new Error("Not implemented");
   }
 
@@ -140,7 +137,7 @@ export class WebSocketConnection {
   /**
    * Called by the `transport` when the connection is closed.
    */
-  onConnectionClose(status) {
+  onConnectionClose() {
     lazy.logger.debug(`${this.constructor.name} ${this.id} closed`);
   }
 
diff --git a/remote/shared/js-window-actors/NavigationListenerChild.sys.mjs b/remote/shared/js-window-actors/NavigationListenerChild.sys.mjs
index a2cd8ccf10..728d9b6e8c 100644
--- a/remote/shared/js-window-actors/NavigationListenerChild.sys.mjs
+++ b/remote/shared/js-window-actors/NavigationListenerChild.sys.mjs
@@ -56,12 +56,12 @@ export class NavigationListenerChild extends JSWindowActorChild {
   /**
    * See note above
    */
-  handleEvent(event) {}
+  handleEvent() {}
 
   /**
    * See note above
    */
-  receiveMessage(message) {}
+  receiveMessage() {}
 
   /**
    * A browsing context might be replaced before reaching the parent process,
diff --git a/remote/shared/listeners/ContextualIdentityListener.sys.mjs b/remote/shared/listeners/ContextualIdentityListener.sys.mjs
index d93b44ed77..42954d223c 100644
--- a/remote/shared/listeners/ContextualIdentityListener.sys.mjs
+++ b/remote/shared/listeners/ContextualIdentityListener.sys.mjs
@@ -49,7 +49,7 @@ export class ContextualIdentityListener {
     this.stopListening();
   }
 
-  observe(subject, topic, data) {
+  observe(subject, topic) {
     switch (topic) {
       case OBSERVER_TOPIC_CREATED:
         this.emit("created", { identity: subject.wrappedJSObject });
diff --git a/remote/shared/listeners/NetworkEventRecord.sys.mjs b/remote/shared/listeners/NetworkEventRecord.sys.mjs
index a41f3edd7d..72b43e3de1 100644
--- a/remote/shared/listeners/NetworkEventRecord.sys.mjs
+++ b/remote/shared/listeners/NetworkEventRecord.sys.mjs
@@ -163,13 +163,8 @@ export class NetworkEventRecord {
    * Required API for a NetworkObserver event owner.
    *
    * Not used for RemoteAgent.
-   *
-   * @param {object} info
-   *     The object containing security information.
-   * @param {boolean} isRacing
-   *     True if the corresponding channel raced the cache and network requests.
    */
-  addSecurityInfo(info, isRacing) {}
+  addSecurityInfo() {}
 
   /**
    * Add network event timings.
@@ -177,15 +172,8 @@ export class NetworkEventRecord {
    * Required API for a NetworkObserver event owner.
    *
    * Not used for RemoteAgent.
-   *
-   * @param {number} total
-   *     The total time for the request.
-   * @param {object} timings
-   *     The har-like timings.
-   * @param {object} offsets
-   *     The har-like timings, but as offset from the request start.
    */
-  addEventTimings(total, timings, offsets) {}
+  addEventTimings() {}
 
   /**
    * Add response cache entry.
@@ -193,11 +181,8 @@ export class NetworkEventRecord {
    * Required API for a NetworkObserver event owner.
    *
    * Not used for RemoteAgent.
-   *
-   * @param {object} options
-   *     An object which contains a single responseCache property.
    */
-  addResponseCache(options) {}
+  addResponseCache() {}
 
   /**
    * Add response content.
@@ -233,11 +218,8 @@ export class NetworkEventRecord {
    * Required API for a NetworkObserver event owner.
    *
    * Not used for RemoteAgent.
-   *
-   * @param {Array} serverTimings
-   *     The server timings.
    */
-  addServerTimings(serverTimings) {}
+  addServerTimings() {}
 
   /**
    * Add service worker timings.
@@ -245,11 +227,8 @@ export class NetworkEventRecord {
    * Required API for a NetworkObserver event owner.
    *
    * Not used for RemoteAgent.
-   *
-   * @param {object} serviceWorkerTimings
-   *     The server timings.
    */
-  addServiceWorkerTimings(serviceWorkerTimings) {}
+  addServiceWorkerTimings() {}
 
   onAuthPrompt(authDetails, authCallbacks) {
     this.#emitAuthRequired(authCallbacks);
diff --git a/remote/shared/listeners/test/browser/browser_NetworkListener.js b/remote/shared/listeners/test/browser/browser_NetworkListener.js
index 78865f6b80..cc1b42f2fc 100644
--- a/remote/shared/listeners/test/browser/browser_NetworkListener.js
+++ b/remote/shared/listeners/test/browser/browser_NetworkListener.js
@@ -32,22 +32,22 @@ add_task(async function test_beforeRequestSent() {
   listener.startListening();
 
   await fetch(tab1.linkedBrowser, "https://example.com/?1");
-  ok(events.length == 1, "One event was received");
+  Assert.equal(events.length, 1, "One event was received");
   assertNetworkEvent(events[0], contextId1, "https://example.com/?1");
 
   info("Check that events are no longer emitted after calling stopListening");
   listener.stopListening();
   await fetch(tab1.linkedBrowser, "https://example.com/?2");
-  ok(events.length == 1, "No new event was received");
+  Assert.equal(events.length, 1, "No new event was received");
 
   listener.startListening();
   await fetch(tab1.linkedBrowser, "https://example.com/?3");
-  ok(events.length == 2, "A new event was received");
+  Assert.equal(events.length, 2, "A new event was received");
   assertNetworkEvent(events[1], contextId1, "https://example.com/?3");
 
   info("Check network event from the new tab");
   await fetch(tab2.linkedBrowser, "https://example.com/?4");
-  ok(events.length == 3, "A new event was received");
+  Assert.equal(events.length, 3, "A new event was received");
   assertNetworkEvent(events[2], contextId2, "https://example.com/?4");
 
   gBrowser.removeTab(tab1);
diff --git a/remote/shared/listeners/test/browser/browser_PromptListener.js b/remote/shared/listeners/test/browser/browser_PromptListener.js
index 0d3f23db3f..30503ef4fa 100644
--- a/remote/shared/listeners/test/browser/browser_PromptListener.js
+++ b/remote/shared/listeners/test/browser/browser_PromptListener.js
@@ -156,7 +156,7 @@ add_task(async function test_events_in_another_browser() {
   await createScriptNode(`setTimeout(() => window.confirm('test'))`);
   const dialogWin = await dialogPromise;
 
-  ok(events.length === 0, "No event was received");
+  Assert.strictEqual(events.length, 0, "No event was received");
 
   dialogWin.document.querySelector("dialog").acceptDialog();
 
@@ -166,7 +166,7 @@ add_task(async function test_events_in_another_browser() {
     setTimeout(resolve, 500);
   });
 
-  ok(events.length === 0, "No event was received");
+  Assert.strictEqual(events.length, 0, "No event was received");
 
   listener.destroy();
   await BrowserTestUtils.closeWindow(win);
diff --git a/remote/shared/messagehandler/MessageHandler.sys.mjs b/remote/shared/messagehandler/MessageHandler.sys.mjs
index 18ec6b820c..61c8b5c40e 100644
--- a/remote/shared/messagehandler/MessageHandler.sys.mjs
+++ b/remote/shared/messagehandler/MessageHandler.sys.mjs
@@ -215,7 +215,7 @@ export class MessageHandler extends EventEmitter {
 
   /**
    * Retrieve all module classes matching the moduleName and destination.
-   * See `getAllModuleClasses` (ModuleCache.jsm) for more details.
+   * See `getAllModuleClasses` (ModuleCache.sys.mjs) for more details.
    *
    * @param {string} moduleName
    *     The name of the module.
@@ -267,11 +267,8 @@ export class MessageHandler extends EventEmitter {
    * provided to this MessageHandler on startup. Implementation is specific to each MessageHandler class.
    *
    * By default the implementation is a no-op.
-   *
-   * @param {Array<SessionDataItem>} sessionDataItems
-   *     Initial session data items for this MessageHandler.
    */
-  async initialize(sessionDataItems) {}
+  async initialize() {}
 
   /**
    * Returns the module path corresponding to this MessageHandler class.
@@ -297,7 +294,7 @@ export class MessageHandler extends EventEmitter {
    *
    * Needs to be implemented in the sub class.
    */
-  static getIdFromContext(context) {
+  static getIdFromContext() {
     throw new Error("Not implemented");
   }
 
@@ -306,7 +303,7 @@ export class MessageHandler extends EventEmitter {
    *
    * Needs to be implemented in the sub class.
    */
-  forwardCommand(command) {
+  forwardCommand() {
     throw new Error("Not implemented");
   }
 
@@ -316,7 +313,7 @@ export class MessageHandler extends EventEmitter {
    *
    * Needs to be implemented in the sub class.
    */
-  matchesContext(contextDescriptor) {
+  matchesContext() {
     throw new Error("Not implemented");
   }
 
diff --git a/remote/shared/messagehandler/Module.sys.mjs b/remote/shared/messagehandler/Module.sys.mjs
index 30b26938e2..c526c7ce6c 100644
--- a/remote/shared/messagehandler/Module.sys.mjs
+++ b/remote/shared/messagehandler/Module.sys.mjs
@@ -61,12 +61,12 @@ export class Module {
    *
    * @param {string} name
    *     Name of the event.
-   * @param {object} payload
+   * @param {object} _payload
    *    The event's payload.
    * @returns {object}
    *     The modified event payload.
    */
-  interceptEvent(name, payload) {
+  interceptEvent(name, _payload) {
     throw new Error(
       `Could not intercept event ${name}, interceptEvent is not implemented in windowglobal-in-root module`
     );
diff --git a/remote/shared/messagehandler/RootMessageHandler.sys.mjs b/remote/shared/messagehandler/RootMessageHandler.sys.mjs
index 06a8cd6f18..ce571c3c12 100644
--- a/remote/shared/messagehandler/RootMessageHandler.sys.mjs
+++ b/remote/shared/messagehandler/RootMessageHandler.sys.mjs
@@ -51,7 +51,7 @@ export class RootMessageHandler extends MessageHandler {
    * The ROOT MessageHandler is unique for a given MessageHandler network
    * (ie for a given sessionId). Reuse the type as context id here.
    */
-  static getIdFromContext(context) {
+  static getIdFromContext() {
     return RootMessageHandler.type;
   }
 
diff --git a/remote/shared/messagehandler/sessiondata/SessionDataReader.sys.mjs b/remote/shared/messagehandler/sessiondata/SessionDataReader.sys.mjs
index 6d5ea08e59..f7c91e6bbf 100644
--- a/remote/shared/messagehandler/sessiondata/SessionDataReader.sys.mjs
+++ b/remote/shared/messagehandler/sessiondata/SessionDataReader.sys.mjs
@@ -18,7 +18,7 @@ ChromeUtils.defineLazyGetter(lazy, "sharedData", () => {
 
 /**
  * Returns a snapshot of the session data map, which is cloned from the
- * sessionDataMap singleton of SessionData.jsm.
+ * sessionDataMap singleton of SessionData.sys.mjs.
  *
  *  @returns {Map.<string, Array<SessionDataItem>>}
  *     Map of session id to arrays of SessionDataItems.
diff --git a/remote/shared/messagehandler/test/browser/resources/modules/windowglobal/retry.sys.mjs b/remote/shared/messagehandler/test/browser/resources/modules/windowglobal/retry.sys.mjs
index f7b2279018..3022744e7c 100644
--- a/remote/shared/messagehandler/test/browser/resources/modules/windowglobal/retry.sys.mjs
+++ b/remote/shared/messagehandler/test/browser/resources/modules/windowglobal/retry.sys.mjs
@@ -27,7 +27,7 @@ class RetryModule extends Module {
     // processes.
     const uri = this.messageHandler.window.document.baseURI;
     if (!uri.includes("example.net")) {
-      await new Promise(r => {});
+      await new Promise(() => {});
     }
 
     return { ...params };
@@ -37,7 +37,7 @@ class RetryModule extends Module {
   async blockedOneTime(params) {
     callsToBlockedOneTime++;
     if (callsToBlockedOneTime < 2) {
-      await new Promise(r => {});
+      await new Promise(() => {});
     }
 
     // Return:
@@ -51,7 +51,7 @@ class RetryModule extends Module {
   async blockedTenTimes(params) {
     callsToBlockedTenTimes++;
     if (callsToBlockedTenTimes < 11) {
-      await new Promise(r => {});
+      await new Promise(() => {});
     }
 
     // Return:
@@ -65,7 +65,7 @@ class RetryModule extends Module {
   async blockedElevenTimes(params) {
     callsToBlockedElevenTimes++;
     if (callsToBlockedElevenTimes < 12) {
-      await new Promise(r => {});
+      await new Promise(() => {});
     }
 
     // Return:
diff --git a/remote/shared/messagehandler/test/browser/resources/modules/windowglobal/windowglobaltoroot.sys.mjs b/remote/shared/messagehandler/test/browser/resources/modules/windowglobal/windowglobaltoroot.sys.mjs
index 815a836d9c..1d9238f1bc 100644
--- a/remote/shared/messagehandler/test/browser/resources/modules/windowglobal/windowglobaltoroot.sys.mjs
+++ b/remote/shared/messagehandler/test/browser/resources/modules/windowglobal/windowglobaltoroot.sys.mjs
@@ -17,7 +17,7 @@ class WindowGlobalToRootModule extends Module {
    * Commands
    */
 
-  testHandleCommandToRoot(params, destination) {
+  testHandleCommandToRoot() {
     return this.messageHandler.handleCommand({
       moduleName: "windowglobaltoroot",
       commandName: "getValueFromRoot",
@@ -27,7 +27,7 @@ class WindowGlobalToRootModule extends Module {
     });
   }
 
-  testSendRootCommand(params, destination) {
+  testSendRootCommand() {
     return this.messageHandler.sendRootCommand({
       moduleName: "windowglobaltoroot",
       commandName: "getValueFromRoot",
diff --git a/remote/shared/test/browser/browser_UserContextManager.js b/remote/shared/test/browser/browser_UserContextManager.js
index 2060c2bacd..cfae75dbe2 100644
--- a/remote/shared/test/browser/browser_UserContextManager.js
+++ b/remote/shared/test/browser/browser_UserContextManager.js
@@ -159,8 +159,9 @@ add_task(async function test_several_managers() {
     "manager2 has a valid id for the user context created by manager 1"
   );
 
-  ok(
-    contextId1 != contextId2,
+  Assert.notEqual(
+    contextId1,
+    contextId2,
     "manager1 and manager2 have different ids for the same internal context id"
   );
 
diff --git a/remote/shared/test/xpcshell/test_RecommendedPreferences.js b/remote/shared/test/xpcshell/test_RecommendedPreferences.js
index 20de07a528..88dc717be8 100644
--- a/remote/shared/test/xpcshell/test_RecommendedPreferences.js
+++ b/remote/shared/test/xpcshell/test_RecommendedPreferences.js
@@ -76,6 +76,11 @@ add_task(async function test_disabled() {
 
 add_task(async function test_noCustomPreferences() {
   info("Applying preferences without any custom preference should not throw");
+
+  // First call invokes setting of default preferences
+  RecommendedPreferences.applyPreferences();
+
+  // Second call does nothing
   RecommendedPreferences.applyPreferences();
 
   cleanup();
diff --git a/remote/shared/test/xpcshell/test_Sync.js b/remote/shared/test/xpcshell/test_Sync.js
index de4a4d30fe..a85c47adc2 100644
--- a/remote/shared/test/xpcshell/test_Sync.js
+++ b/remote/shared/test/xpcshell/test_Sync.js
@@ -50,14 +50,14 @@ class MockElement {
     }
   }
 
-  dispatchEvent(event) {
+  dispatchEvent() {
     if (this.wantUntrusted) {
       this.untrusted = true;
     }
     this.click();
   }
 
-  removeEventListener(name, func) {
+  removeEventListener() {
     this.capture = false;
     this.eventName = null;
     this.func = null;
@@ -213,12 +213,12 @@ add_task(async function test_EventPromise_checkFnCallback() {
     { checkFn: null, expected_count: 0 },
     { checkFn: undefined, expected_count: 0 },
     {
-      checkFn: event => {
+      checkFn: () => {
         throw new Error("foo");
       },
       expected_count: 0,
     },
-    { checkFn: event => count++ > 0, expected_count: 2 },
+    { checkFn: () => count++ > 0, expected_count: 2 },
   ];
 
   for (const { checkFn, expected_count } of data) {
@@ -417,7 +417,7 @@ add_task(async function test_PollPromise_resolve() {
   const timeout = 100;
 
   await new PollPromise(
-    (resolve, reject) => {
+    resolve => {
       resolve();
     },
     { timeout, errorMessage }
diff --git a/remote/shared/webdriver/Actions.sys.mjs b/remote/shared/webdriver/Actions.sys.mjs
index 4f5a41a421..2639c4dc9f 100644
--- a/remote/shared/webdriver/Actions.sys.mjs
+++ b/remote/shared/webdriver/Actions.sys.mjs
@@ -13,7 +13,7 @@ ChromeUtils.defineESModuleGetters(lazy, {
   clearTimeout: "resource://gre/modules/Timer.sys.mjs",
   dom: "chrome://remote/content/shared/DOM.sys.mjs",
   error: "chrome://remote/content/shared/webdriver/Errors.sys.mjs",
-  event: "chrome://remote/content/marionette/event.sys.mjs",
+  event: "chrome://remote/content/shared/webdriver/Event.sys.mjs",
   keyData: "chrome://remote/content/shared/webdriver/KeyData.sys.mjs",
   Log: "chrome://remote/content/shared/Log.sys.mjs",
   pprint: "chrome://remote/content/shared/Format.sys.mjs",
@@ -508,11 +508,8 @@ class Origin {
    * Viewport coordinates of the origin of this coordinate system.
    *
    * This is overridden in subclasses to provide a class-specific origin.
-   *
-   * @param {InputSource} inputSource - State of current input device.
-   * @param {WindowProxy} win - Current window global
    */
-  getOriginCoordinates(inputSource, win) {
+  getOriginCoordinates() {
     throw new Error(
       `originCoordinates not defined for ${this.constructor.name}`
     );
@@ -559,13 +556,13 @@ class Origin {
 }
 
 class ViewportOrigin extends Origin {
-  getOriginCoordinates(inputSource, win) {
+  getOriginCoordinates() {
     return { x: 0, y: 0 };
   }
 }
 
 class PointerOrigin extends Origin {
-  getOriginCoordinates(inputSource, win) {
+  getOriginCoordinates(inputSource) {
     return { x: inputSource.x, y: inputSource.y };
   }
 }
@@ -624,13 +621,9 @@ class Action {
    * This is overridden by subclasses to implement the type-specific
    * dispatch of the action.
    *
-   * @param {State} state - Actions state.
-   * @param {InputSource} inputSource - State of the current input device.
-   * @param {number} tickDuration - Length of the current tick, in ms.
-   * @param {WindowProxy} win - Current window global.
    * @returns {Promise} - Promise that is resolved once the action is complete.
    */
-  dispatch(state, inputSource, tickDuration, win) {
+  dispatch() {
     throw new Error(
       `Action subclass ${this.constructor.name} must override dispatch()`
     );
@@ -708,10 +701,9 @@ class PauseAction extends NullAction {
    * @param {State} state - Actions state.
    * @param {InputSource} inputSource - State of the current input device.
    * @param {number} tickDuration - Length of the current tick, in ms.
-   * @param {WindowProxy} win - Current window global.
    * @returns {Promise} - Promise that is resolved once the action is complete.
    */
-  dispatch(state, inputSource, tickDuration, win) {
+  dispatch(state, inputSource, tickDuration) {
     const ms = this.duration ?? tickDuration;
 
     lazy.logger.trace(
@@ -1416,15 +1408,9 @@ class TouchActionGroup {
    * This is overridden by subclasses to implement the type-specific
    * dispatch of the action.
    *
-   * @param {State} state - Actions state.
-   * @param {null} inputSource
-   *     This is always null; the argument only exists for compatibility
-   *     with {@link Action.dispatch}.
-   * @param {number} tickDuration - Length of the current tick, in ms.
-   * @param {WindowProxy} win - Current window global.
    * @returns {Promise} - Promise that is resolved once the action is complete.
    */
-  dispatch(state, inputSource, tickDuration, win) {
+  dispatch() {
     throw new Error(
       "TouchActionGroup subclass missing dispatch implementation"
     );
@@ -1622,7 +1608,7 @@ class PointerMoveTouchActionGroup extends TouchActionGroup {
       }
     );
     const reachedTarget = perPointerData.every(
-      ([inputSource, action, target]) =>
+      ([inputSource, , target]) =>
         target[0] === inputSource.x && target[1] === inputSource.y
     );
 
@@ -1778,38 +1764,22 @@ class Pointer {
 
   /**
    * Implementation of depressing the pointer.
-   *
-   * @param {State} state - Actions state.
-   * @param {InputSource} inputSource - State of the current input device.
-   * @param {Action} action - The Action object invoking the pointer
-   * @param {WindowProxy} win - Current window global.
    */
-  pointerDown(state, inputSource, action, win) {
+  pointerDown() {
     throw new Error(`Unimplemented pointerDown for pointerType ${this.type}`);
   }
 
   /**
    * Implementation of releasing the pointer.
-   *
-   * @param {State} state - Actions state.
-   * @param {InputSource} inputSource - State of the current input device.
-   * @param {Action} action - The Action object invoking the pointer
-   * @param {WindowProxy} win - Current window global.
    */
-  pointerUp(state, inputSource, action, win) {
+  pointerUp() {
     throw new Error(`Unimplemented pointerUp for pointerType ${this.type}`);
   }
 
   /**
    * Implementation of moving the pointer.
-   *
-   * @param {State} state - Actions state.
-   * @param {InputSource} inputSource - State of the current input device.
-   * @param {number} targetX - Target X coordinate of the pointer move
-   * @param {number} targetY - Target Y coordinate of the pointer move
-   * @param {WindowProxy} win - Current window global.
    */
-  pointerMove(state, inputSource, targetX, targetY, win) {
+  pointerMove() {
     throw new Error(`Unimplemented pointerMove for pointerType ${this.type}`);
   }
 
@@ -2138,11 +2108,8 @@ class InputEventData {
 
   /**
    * Update the input data based on global and input state
-   *
-   * @param {State} state - Actions state.
-   * @param {InputSource} inputSource - State of the current input device.
    */
-  update(state, inputSource) {}
+  update() {}
 
   toString() {
     return `${this.constructor.name} ${JSON.stringify(this)}`;
diff --git a/remote/shared/webdriver/Capabilities.sys.mjs b/remote/shared/webdriver/Capabilities.sys.mjs
index e3761315f2..3c30ea0789 100644
--- a/remote/shared/webdriver/Capabilities.sys.mjs
+++ b/remote/shared/webdriver/Capabilities.sys.mjs
@@ -445,6 +445,12 @@ export class Capabilities extends Map {
       ["timeouts", new Timeouts()],
       ["strictFileInteractability", false],
       ["unhandledPromptBehavior", UnhandledPromptBehavior.DismissAndNotify],
+      [
+        "userAgent",
+        Cc["@mozilla.org/network/protocol;1?name=http"].getService(
+          Ci.nsIHttpProtocolHandler
+        ).userAgent,
+      ],
       ["webSocketUrl", null],
 
       // proprietary
diff --git a/remote/shared/webdriver/Errors.sys.mjs b/remote/shared/webdriver/Errors.sys.mjs
index 53b9d4426b..7060131075 100644
--- a/remote/shared/webdriver/Errors.sys.mjs
+++ b/remote/shared/webdriver/Errors.sys.mjs
@@ -41,6 +41,7 @@ const ERRORS = new Set([
   "TimeoutError",
   "UnableToCaptureScreen",
   "UnableToSetCookieError",
+  "UnableToSetFileInputError",
   "UnexpectedAlertOpenError",
   "UnknownCommandError",
   "UnknownError",
@@ -757,6 +758,21 @@ class UnableToSetCookieError extends WebDriverError {
 }
 
 /**
+ * A command to set a file could not be satisfied.
+ *
+ * @param {string=} message
+ *     Optional string describing error situation.
+ * @param {object=} data
+ *     Additional error data helpful in diagnosing the error.
+ */
+class UnableToSetFileInputError extends WebDriverError {
+  constructor(message, data = {}) {
+    super(message, data);
+    this.status = "unable to set file input";
+  }
+}
+
+/**
  * A command to capture a screenshot could not be satisfied.
  *
  * @param {string=} message
@@ -865,6 +881,7 @@ const STATUSES = new Map([
   ["timeout", TimeoutError],
   ["unable to capture screen", UnableToCaptureScreen],
   ["unable to set cookie", UnableToSetCookieError],
+  ["unable to set file input", UnableToSetFileInputError],
   ["unexpected alert open", UnexpectedAlertOpenError],
   ["unknown command", UnknownCommandError],
   ["unknown error", UnknownError],
diff --git a/remote/shared/webdriver/Event.sys.mjs b/remote/shared/webdriver/Event.sys.mjs
new file mode 100644
index 0000000000..2240f1f2b2
--- /dev/null
+++ b/remote/shared/webdriver/Event.sys.mjs
@@ -0,0 +1,295 @@
+/* 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/. */
+
+/* eslint-disable no-restricted-globals */
+
+const lazy = {};
+
+ChromeUtils.defineESModuleGetters(lazy, {
+  keyData: "chrome://remote/content/shared/webdriver/KeyData.sys.mjs",
+});
+
+/** Provides functionality for creating and sending DOM events. */
+export const event = {};
+
+const _eventUtils = new WeakMap();
+
+function _getEventUtils(win) {
+  if (!_eventUtils.has(win)) {
+    const eventUtilsObject = {
+      window: win,
+      parent: win,
+      _EU_Ci: Ci,
+      _EU_Cc: Cc,
+    };
+    Services.scriptloader.loadSubScript(
+      "chrome://remote/content/external/EventUtils.js",
+      eventUtilsObject
+    );
+    _eventUtils.set(win, eventUtilsObject);
+  }
+  return _eventUtils.get(win);
+}
+
+event.MouseEvents = {
+  click: 0,
+  dblclick: 1,
+  mousedown: 2,
+  mouseup: 3,
+  mouseover: 4,
+  mouseout: 5,
+};
+
+event.Modifiers = {
+  shiftKey: 0,
+  ctrlKey: 1,
+  altKey: 2,
+  metaKey: 3,
+};
+
+event.MouseButton = {
+  isPrimary(button) {
+    return button === 0;
+  },
+  isAuxiliary(button) {
+    return button === 1;
+  },
+  isSecondary(button) {
+    return button === 2;
+  },
+};
+
+/**
+ * Synthesise a mouse event at a point.
+ *
+ * If the type is specified in opts, an mouse event of that type is
+ * fired. Otherwise, a mousedown followed by a mouseup is performed.
+ *
+ * @param {number} left
+ *     Offset from viewport left, in CSS pixels
+ * @param {number} top
+ *     Offset from viewport top, in CSS pixels
+ * @param {object} opts
+ *     Object which may contain the properties "shiftKey", "ctrlKey",
+ *     "altKey", "metaKey", "accessKey", "clickCount", "button", and
+ *     "type".
+ * @param {Window} win
+ *     Window object.
+ *
+ * @returns {boolean} defaultPrevented
+ */
+event.synthesizeMouseAtPoint = function (left, top, opts, win) {
+  return _getEventUtils(win).synthesizeMouseAtPoint(left, top, opts, win);
+};
+
+/**
+ * Synthesise a touch event at a point.
+ *
+ * If the type is specified in opts, a touch event of that type is
+ * fired. Otherwise, a touchstart followed by a touchend is performed.
+ *
+ * @param {number} left
+ *     Offset from viewport left, in CSS pixels
+ * @param {number} top
+ *     Offset from viewport top, in CSS pixels
+ * @param {object} opts
+ *     Object which may contain the properties "id", "rx", "ry", "angle",
+ *     "force", "shiftKey", "ctrlKey", "altKey", "metaKey", "accessKey",
+ *     "type".
+ * @param {Window} win
+ *     Window object.
+ *
+ * @returns {boolean} defaultPrevented
+ */
+event.synthesizeTouchAtPoint = function (left, top, opts, win) {
+  return _getEventUtils(win).synthesizeTouchAtPoint(left, top, opts, win);
+};
+
+/**
+ * Synthesise a wheel scroll event at a point.
+ *
+ * @param {number} left
+ *     Offset from viewport left, in CSS pixels
+ * @param {number} top
+ *     Offset from viewport top, in CSS pixels
+ * @param {object} opts
+ *     Object which may contain the properties "shiftKey", "ctrlKey",
+ *     "altKey", "metaKey", "accessKey", "deltaX", "deltaY", "deltaZ",
+ *     "deltaMode", "lineOrPageDeltaX", "lineOrPageDeltaY", "isMomentum",
+ *     "isNoLineOrPageDelta", "isCustomizedByPrefs", "expectedOverflowDeltaX",
+ *     "expectedOverflowDeltaY"
+ * @param {Window} win
+ *     Window object.
+ */
+event.synthesizeWheelAtPoint = function (left, top, opts, win) {
+  const dpr = win.devicePixelRatio;
+
+  // All delta properties expect the value in device pixels while the
+  // WebDriver specification uses CSS pixels.
+  if (typeof opts.deltaX !== "undefined") {
+    opts.deltaX *= dpr;
+  }
+  if (typeof opts.deltaY !== "undefined") {
+    opts.deltaY *= dpr;
+  }
+  if (typeof opts.deltaZ !== "undefined") {
+    opts.deltaZ *= dpr;
+  }
+
+  return _getEventUtils(win).synthesizeWheelAtPoint(left, top, opts, win);
+};
+
+event.synthesizeMultiTouch = function (opts, win) {
+  const modifiers = _getEventUtils(win)._parseModifiers(opts);
+  win.windowUtils.sendTouchEvent(
+    opts.type,
+    opts.id,
+    opts.x,
+    opts.y,
+    opts.rx,
+    opts.ry,
+    opts.angle,
+    opts.force,
+    opts.tiltx,
+    opts.tilty,
+    opts.twist,
+    modifiers
+  );
+};
+
+/**
+ * Synthesize a keydown event for a single key.
+ *
+ * @param {object} key
+ *     Key data as returned by keyData.getData
+ * @param {Window} win
+ *     Window object.
+ */
+event.sendKeyDown = function (key, win) {
+  event.sendSingleKey(key, win, "keydown");
+};
+
+/**
+ * Synthesize a keyup event for a single key.
+ *
+ * @param {object} key
+ *     Key data as returned by keyData.getData
+ * @param {Window} win
+ *     Window object.
+ */
+event.sendKeyUp = function (key, win) {
+  event.sendSingleKey(key, win, "keyup");
+};
+
+/**
+ * Synthesize a key event for a single key.
+ *
+ * @param {object} key
+ *     Key data as returned by keyData.getData
+ * @param {Window} win
+ *     Window object.
+ * @param {string=} type
+ *     Event to emit. By default the full keydown/keypressed/keyup event
+ *     sequence is emitted.
+ */
+event.sendSingleKey = function (key, win, type = null) {
+  let keyValue = key.key;
+  if (!key.printable) {
+    keyValue = `KEY_${keyValue}`;
+  }
+  const event = {
+    code: key.code,
+    location: key.location,
+    altKey: key.altKey ?? false,
+    shiftKey: key.shiftKey ?? false,
+    ctrlKey: key.ctrlKey ?? false,
+    metaKey: key.metaKey ?? false,
+    repeat: key.repeat ?? false,
+  };
+  if (type) {
+    event.type = type;
+  }
+  _getEventUtils(win).synthesizeKey(keyValue, event, win);
+};
+
+/**
+ * Send a string as a series of keypresses.
+ *
+ * @param {string} keyString
+ *     Sequence of characters to send as key presses
+ * @param {Window} win
+ *     Window object
+ */
+event.sendKeys = function (keyString, win) {
+  const modifiers = {};
+  for (let modifier in event.Modifiers) {
+    modifiers[modifier] = false;
+  }
+
+  for (let keyValue of keyString) {
+    // keyValue will contain enough to represent the UTF-16 encoding of a single abstract character
+    // i.e. either a single scalar value, or a surrogate pair
+    if (modifiers.shiftKey) {
+      keyValue = lazy.keyData.getShiftedKey(keyValue);
+    }
+    const data = lazy.keyData.getData(keyValue);
+    const key = { ...data, ...modifiers };
+    if (data.modifier) {
+      // Negating the state of the modifier here is not spec compliant but
+      // makes us compatible to Chrome's behavior for now. That's fine unless
+      // we know the correct behavior.
+      //
+      // @see: https://github.com/w3c/webdriver/issues/1734
+      modifiers[data.modifier] = !modifiers[data.modifier];
+    }
+    event.sendSingleKey(key, win);
+  }
+};
+
+event.sendEvent = function (eventType, el, modifiers = {}, opts = {}) {
+  opts.canBubble = opts.canBubble || true;
+
+  let doc = el.ownerDocument || el.document;
+  let ev = doc.createEvent("Event");
+
+  ev.shiftKey = modifiers.shift;
+  ev.metaKey = modifiers.meta;
+  ev.altKey = modifiers.alt;
+  ev.ctrlKey = modifiers.ctrl;
+
+  ev.initEvent(eventType, opts.canBubble, true);
+  el.dispatchEvent(ev);
+};
+
+event.mouseover = function (el, modifiers = {}, opts = {}) {
+  return event.sendEvent("mouseover", el, modifiers, opts);
+};
+
+event.mousemove = function (el, modifiers = {}, opts = {}) {
+  return event.sendEvent("mousemove", el, modifiers, opts);
+};
+
+event.mousedown = function (el, modifiers = {}, opts = {}) {
+  return event.sendEvent("mousedown", el, modifiers, opts);
+};
+
+event.mouseup = function (el, modifiers = {}, opts = {}) {
+  return event.sendEvent("mouseup", el, modifiers, opts);
+};
+
+event.cancel = function (el, modifiers = {}, opts = {}) {
+  return event.sendEvent("cancel", el, modifiers, opts);
+};
+
+event.click = function (el, modifiers = {}, opts = {}) {
+  return event.sendEvent("click", el, modifiers, opts);
+};
+
+event.change = function (el, modifiers = {}, opts = {}) {
+  return event.sendEvent("change", el, modifiers, opts);
+};
+
+event.input = function (el, modifiers = {}, opts = {}) {
+  return event.sendEvent("input", el, modifiers, opts);
+};
diff --git a/remote/shared/webdriver/process-actors/WebDriverProcessDataChild.sys.mjs b/remote/shared/webdriver/process-actors/WebDriverProcessDataChild.sys.mjs
index 39db9d939e..8101240abe 100644
--- a/remote/shared/webdriver/process-actors/WebDriverProcessDataChild.sys.mjs
+++ b/remote/shared/webdriver/process-actors/WebDriverProcessDataChild.sys.mjs
@@ -17,7 +17,7 @@ class BrowsingContextObserver {
     this.actor = actor;
   }
 
-  async observe(subject, topic, data) {
+  async observe(subject, topic) {
     if (topic === "browsing-context-discarded") {
       this.actor.cleanUp({ browsingContext: subject });
     }
diff --git a/remote/shared/webdriver/test/xpcshell/test_Errors.js b/remote/shared/webdriver/test/xpcshell/test_Errors.js
index 22e3526039..d4803dee87 100644
--- a/remote/shared/webdriver/test/xpcshell/test_Errors.js
+++ b/remote/shared/webdriver/test/xpcshell/test_Errors.js
@@ -36,6 +36,7 @@ const errors = [
   error.StaleElementReferenceError,
   error.TimeoutError,
   error.UnableToSetCookieError,
+  error.UnableToSetFileInputError,
   error.UnexpectedAlertOpenError,
   error.UnknownCommandError,
   error.UnknownError,
@@ -510,6 +511,14 @@ add_task(function test_UnableToSetCookieError() {
   ok(err instanceof error.WebDriverError);
 });
 
+add_task(function test_UnableToSetFileInputError() {
+  let err = new error.UnableToSetFileInputError("foo");
+  equal("UnableToSetFileInputError", err.name);
+  equal("foo", err.message);
+  equal("unable to set file input", err.status);
+  ok(err instanceof error.WebDriverError);
+});
+
 add_task(function test_UnexpectedAlertOpenError() {
   let err = new error.UnexpectedAlertOpenError("foo");
   equal("UnexpectedAlertOpenError", err.name);