Bug 1770492 - [messagehandler] Support emitting protocol errors from MessageHandler modules r=webdriver-reviewers,whimboo

Differential Revision: https://phabricator.services.mozilla.com/D151034

remote/jar.mn

@@ -19,6 +19,7 @@ remote.jar:
   content/shared/Navigate.jsm (shared/Navigate.jsm)
   content/shared/PDF.jsm (shared/PDF.jsm)
   content/shared/RecommendedPreferences.jsm (shared/RecommendedPreferences.jsm)
+  content/shared/RemoteError.jsm (shared/RemoteError.jsm)
   content/shared/Stack.jsm (shared/Stack.jsm)
   content/shared/Sync.jsm (shared/Sync.jsm)
   content/shared/TabManager.jsm (shared/TabManager.jsm)

remote/shared/RemoteError.jsm

@@ -0,0 +1,23 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const EXPORTED_SYMBOLS = ["RemoteError"];
+
+/**
+ * Base class for all remote protocol errors.
+ */
+class RemoteError extends Error {
+  get isRemoteError() {
+    return true;
+  }
+
+  /**
+   * Convert to a serializable object. Should be implemented by subclasses.
+   */
+  toJSON() {
+    throw new Error("Not implemented");
+  }
+}

remote/shared/messagehandler/Errors.jsm

@@ -6,7 +6,11 @@
 
 const EXPORTED_SYMBOLS = ["error"];
 
-class MessageHandlerError extends Error {
+const { RemoteError } = ChromeUtils.import(
+  "chrome://remote/content/shared/RemoteError.jsm"
+);
+
+class MessageHandlerError extends RemoteError {
   /**
    * @param {(string|Error)=} x
    *     Optional string describing error situation or Error instance
@@ -23,6 +27,10 @@ class MessageHandlerError extends Error {
     }
   }
 
+  get isMessageHandlerError() {
+    return true;
+  }
+
   /**
    * @return {Object.<string, string>}
    *     JSON serialisation of error prototype.

remote/shared/messagehandler/transports/js-window-actors/MessageHandlerFrameChild.jsm

@@ -13,7 +13,6 @@ const { XPCOMUtils } = ChromeUtils.importESModule(
 const lazy = {};
 
 XPCOMUtils.defineLazyModuleGetters(lazy, {
-  error: "chrome://remote/content/shared/messagehandler/Errors.jsm",
   isBrowsingContextCompatible:
     "chrome://remote/content/shared/messagehandler/transports/FrameContextUtils.jsm",
   MessageHandlerRegistry:
@@ -59,9 +58,10 @@ class MessageHandlerFrameChild extends JSWindowActorChild {
       try {
         return await messageHandler.handleCommand(command);
       } catch (e) {
-        if (e instanceof lazy.error.MessageHandlerError) {
+        if (e?.isRemoteError) {
           return {
             error: e.toJSON(),
+            isMessageHandlerError: e.isMessageHandlerError,
           };
         }
         throw e;

remote/shared/messagehandler/transports/js-window-actors/MessageHandlerFrameParent.jsm

@@ -20,6 +20,12 @@ XPCOMUtils.defineLazyModuleGetters(lazy, {
     "chrome://remote/content/shared/messagehandler/WindowGlobalMessageHandler.jsm",
 });
 
+XPCOMUtils.defineLazyGetter(lazy, "WebDriverError", () => {
+  return ChromeUtils.import(
+    "chrome://remote/content/shared/webdriver/Errors.jsm"
+  ).error.WebDriverError;
+});
+
 /**
  * Parent actor for the MessageHandlerFrame JSWindowActor. The
  * MessageHandlerFrame actor is used by FrameTransport to communicate between
@@ -86,7 +92,12 @@ class MessageHandlerFrameParent extends JSWindowActorParent {
     );
 
     if (result?.error) {
-      throw lazy.error.MessageHandlerError.fromJSON(result.error);
+      if (result.isMessageHandlerError) {
+        throw lazy.error.MessageHandlerError.fromJSON(result.error);
+      }
+
+      // TODO: Do not assume WebDriver is the session protocol, see Bug 1779026.
+      throw lazy.WebDriverError.fromJSON(result.error);
     }
 
     return result;

remote/shared/webdriver/Errors.jsm

@@ -10,6 +10,10 @@ const { XPCOMUtils } = ChromeUtils.importESModule(
   "resource://gre/modules/XPCOMUtils.sys.mjs"
 );
 
+const { RemoteError } = ChromeUtils.import(
+  "chrome://remote/content/shared/RemoteError.jsm"
+);
+
 const lazy = {};
 
 XPCOMUtils.defineLazyModuleGetters(lazy, {
@@ -178,7 +182,7 @@ const error = {
  * It should not be used directly, as it does not correspond to a real
  * error in the specification.
  */
-class WebDriverError extends Error {
+class WebDriverError extends RemoteError {
   /**
    * @param {(string|Error)=} x
    *     Optional string describing error situation or Error instance