1 files changed, 102 insertions, 0 deletions
diff --git a/toolkit/actors/BackgroundThumbnailsChild.sys.mjs b/toolkit/actors/BackgroundThumbnailsChild.sys.mjs
new file mode 100644
index 0000000000..3af51b3b80
--- /dev/null
+++ b/toolkit/actors/BackgroundThumbnailsChild.sys.mjs
@@ -0,0 +1,102 @@
+/* vim: set ts=2 sw=2 sts=2 et tw=80: */
+/* 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/. */
+
+const lazy = {};
+
+ChromeUtils.defineESModuleGetters(lazy, {
+  PageThumbUtils: "resource://gre/modules/PageThumbUtils.sys.mjs",
+});
+
+// NOTE: Copied from nsSandboxFlags.h
+/**
+ * This flag prevents content from creating new auxiliary browsing contexts,
+ * e.g. using the target attribute, or the window.open() method.
+ */
+const SANDBOXED_AUXILIARY_NAVIGATION = 0x2;
+
+export class BackgroundThumbnailsChild extends JSWindowActorChild {
+  receiveMessage(message) {
+    switch (message.name) {
+      case "Browser:Thumbnail:ContentInfo": {
+        if (
+          message.data.isImage ||
+          this.contentWindow.ImageDocument.isInstance(this.document)
+        ) {
+          // To avoid sending additional messages between processes, we return
+          // the image data directly with the size info.
+          return lazy.PageThumbUtils.createImageThumbnailCanvas(
+            this.contentWindow,
+            this.document.location,
+            message.data.targetWidth,
+            message.data.backgroundColor
+          );
+        }
+
+        let [width, height] = lazy.PageThumbUtils.getContentSize(
+          this.contentWindow
+        );
+        return { width, height };
+      }
+
+      case "Browser:Thumbnail:LoadURL": {
+        let docShell = this.docShell.QueryInterface(Ci.nsIWebNavigation);
+
+        // We want a low network priority for this service - lower than b/g tabs
+        // etc - so set it to the lowest priority available.
+        docShell
+          .QueryInterface(Ci.nsIDocumentLoader)
+          .loadGroup.QueryInterface(Ci.nsISupportsPriority).priority =
+          Ci.nsISupportsPriority.PRIORITY_LOWEST;
+
+        docShell.allowMedia = false;
+        docShell.allowPlugins = false;
+        docShell.allowContentRetargeting = false;
+        let defaultFlags =
+          Ci.nsIRequest.LOAD_ANONYMOUS |
+          Ci.nsIRequest.LOAD_BYPASS_CACHE |
+          Ci.nsIRequest.INHIBIT_CACHING |
+          Ci.nsIWebNavigation.LOAD_FLAGS_BYPASS_HISTORY;
+        docShell.defaultLoadFlags = defaultFlags;
+        this.browsingContext.sandboxFlags |= SANDBOXED_AUXILIARY_NAVIGATION;
+        docShell.useTrackingProtection = true;
+
+        // Get the document to force a content viewer to be created, otherwise
+        // the first load can fail.
+        if (!this.document) {
+          return false;
+        }
+
+        let loadURIOptions = {
+          // Bug 1498603 verify usages of systemPrincipal here
+          triggeringPrincipal:
+            Services.scriptSecurityManager.getSystemPrincipal(),
+          loadFlags: Ci.nsIWebNavigation.LOAD_FLAGS_STOP_CONTENT,
+        };
+        try {
+          docShell.loadURI(
+            Services.io.newURI(message.data.url),
+            loadURIOptions
+          );
+        } catch (ex) {
+          return false;
+        }
+
+        return true;
+      }
+    }
+
+    return undefined;
+  }
+
+  handleEvent(event) {
+    if (event.type == "DOMDocElementInserted") {
+      // Arrange to prevent (most) popup dialogs for this window - popups done
+      // in the parent (eg, auth) aren't prevented, but alert() etc are.
+      // disableDialogs only works on the current inner window, so it has
+      // to be called every page load, but before scripts run.
+      this.contentWindow.windowUtils.disableDialogs();
+    }
+  }
+}