Bug 1625957: Implement ResourceWatcher for CSS changes. r=ochameau,rcaliman

Differential Revision: https://phabricator.services.mozilla.com/D74599

devtools/shared/resources/legacy-listeners/css-changes.js

@@ -0,0 +1,26 @@
+/* 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 {
+  ResourceWatcher,
+} = require("devtools/shared/resources/resource-watcher");
+
+module.exports = async function({ targetFront, onAvailable }) {
+  const changesFront = await targetFront.getFront("changes");
+
+  // Get all changes collected up to this point by the ChangesActor on the server,
+  // then fire each change as "add-change".
+  const changes = await changesFront.allChanges();
+  await onAvailable(changes.map(change => toResource(change)));
+
+  changesFront.on("add-change", change => onAvailable([toResource(change)]));
+};
+
+function toResource(change) {
+  return Object.assign(change, {
+    resourceType: ResourceWatcher.TYPES.CSS_CHANGE,
+  });
+}

devtools/shared/resources/legacy-listeners/moz.build

@@ -4,6 +4,7 @@
 
 DevToolsModules(
     'console-messages.js',
+    'css-changes.js',
     'error-messages.js',
     'platform-messages.js',
     'root-node.js',

devtools/shared/resources/resource-watcher.js

@@ -421,6 +421,7 @@ class ResourceWatcher {
 
 ResourceWatcher.TYPES = ResourceWatcher.prototype.TYPES = {
   CONSOLE_MESSAGE: "console-message",
+  CSS_CHANGE: "css-change",
   ERROR_MESSAGE: "error-message",
   PLATFORM_MESSAGE: "platform-message",
   DOCUMENT_EVENT: "document-event",
@@ -434,6 +435,8 @@ module.exports = { ResourceWatcher };
 const LegacyListeners = {
   [ResourceWatcher.TYPES
     .CONSOLE_MESSAGE]: require("devtools/shared/resources/legacy-listeners/console-messages"),
+  [ResourceWatcher.TYPES
+    .CSS_CHANGE]: require("devtools/shared/resources/legacy-listeners/css-changes"),
   [ResourceWatcher.TYPES
     .ERROR_MESSAGE]: require("devtools/shared/resources/legacy-listeners/error-messages"),
   [ResourceWatcher.TYPES