1 files changed, 31 insertions, 0 deletions
diff --git a/browser/components/shell/ScreenshotChild.sys.mjs b/browser/components/shell/ScreenshotChild.sys.mjs
new file mode 100644
index 0000000000..994cb1a27e
--- /dev/null
+++ b/browser/components/shell/ScreenshotChild.sys.mjs
@@ -0,0 +1,31 @@
+/* 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 ScreenshotChild extends JSWindowActorChild {
+  receiveMessage(message) {
+    if (message.name == "GetDimensions") {
+      return this.getDimensions();
+    }
+    return null;
+  }
+
+  async getDimensions() {
+    if (this.document.readyState != "complete") {
+      await new Promise(resolve =>
+        this.contentWindow.addEventListener("load", resolve, { once: true })
+      );
+    }
+
+    let { contentWindow } = this;
+
+    return {
+      innerWidth: contentWindow.innerWidth,
+      innerHeight: contentWindow.innerHeight,
+      scrollMinX: contentWindow.scrollMinX,
+      scrollMaxX: contentWindow.scrollMaxX,
+      scrollMinY: contentWindow.scrollMinY,
+      scrollMaxY: contentWindow.scrollMaxY,
+    };
+  }
+}