1 files changed, 72 insertions, 0 deletions
diff --git a/browser/actors/PageStyleParent.sys.mjs b/browser/actors/PageStyleParent.sys.mjs
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+++ b/browser/actors/PageStyleParent.sys.mjs
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+/* 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/. */
+
+export class PageStyleParent extends JSWindowActorParent {
+  // This has the most recent information about the content stylesheets for
+  // that actor. It's populated via the PageStyle:Add and PageStyle:Clear
+  // messages from the content process. It has the following structure:
+  //
+  // filteredStyleSheets (Array):
+  //   An Array of objects with a filtered list representing all stylesheets
+  //   that the current page offers. Each object has the following members:
+  //
+  //   title (String):
+  //     The title of the stylesheet
+  //
+  //   disabled (bool):
+  //     Whether or not the stylesheet is currently applied
+  //
+  //   href (String):
+  //     The URL of the stylesheet. Stylesheets loaded via a data URL will
+  //     have this property set to null.
+  //
+  // preferredStyleSheetSet (bool):
+  //   Whether or not the user currently has the "Default" style selected
+  //   for the current page.
+  #styleSheetInfo = null;
+
+  receiveMessage(msg) {
+    // Check if things are alive:
+    let browser = this.browsingContext.top.embedderElement;
+    if (!browser || browser.ownerGlobal.closed) {
+      return;
+    }
+
+    // We always store information at the top of the frame tree.
+    let actor =
+      this.browsingContext.top.currentWindowGlobal.getActor("PageStyle");
+    switch (msg.name) {
+      case "PageStyle:Add":
+        actor.addSheetInfo(msg.data);
+        break;
+      case "PageStyle:Clear":
+        if (actor == this) {
+          this.#styleSheetInfo = null;
+        }
+        break;
+    }
+  }
+
+  /**
+   * Add/append styleSheets to the _pageStyleSheets weakmap.
+   * @param newSheetData
+   *        The stylesheet data, including new stylesheets to add,
+   *        and the preferred stylesheet set for this document.
+   */
+  addSheetInfo(newSheetData) {
+    let info = this.getSheetInfo();
+    info.filteredStyleSheets.push(...newSheetData.filteredStyleSheets);
+    info.preferredStyleSheetSet ||= newSheetData.preferredStyleSheetSet;
+  }
+
+  getSheetInfo() {
+    if (!this.#styleSheetInfo) {
+      this.#styleSheetInfo = {
+        filteredStyleSheets: [],
+        preferredStyleSheetSet: true,
+      };
+    }
+    return this.#styleSheetInfo;
+  }
+}