1 files changed, 68 insertions, 0 deletions
diff --git a/dom/manifest/ManifestFinder.jsm b/dom/manifest/ManifestFinder.jsm
new file mode 100644
index 000000000..1e9a9fb15
--- /dev/null
+++ b/dom/manifest/ManifestFinder.jsm
@@ -0,0 +1,68 @@
+/* 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 https://mozilla.org/MPL/2.0/. */
+/* globals Components, Task, PromiseMessage */
+"use strict";
+const {
+  utils: Cu
+} = Components;
+Cu.import("resource://gre/modules/PromiseMessage.jsm");
+Cu.import("resource://gre/modules/Task.jsm");
+
+this.ManifestFinder = {// jshint ignore:line
+  /**
+  * Check from content process if DOM Window has a conforming
+  * manifest link relationship.
+  * @param aContent DOM Window to check.
+  * @return {Promise<Boolean>}
+  */
+  contentHasManifestLink(aContent) {
+    if (!aContent || isXULBrowser(aContent)) {
+      throw new TypeError("Invalid input.");
+    }
+    return checkForManifest(aContent);
+  },
+
+  /**
+  * Check from a XUL browser (parent process) if it's content document has a
+  * manifest link relationship.
+  * @param aBrowser The XUL browser to check.
+  * @return {Promise}
+  */
+  browserHasManifestLink: Task.async(
+    function* (aBrowser) {
+      if (!isXULBrowser(aBrowser)) {
+        throw new TypeError("Invalid input.");
+      }
+      const msgKey = "DOM:WebManifest:hasManifestLink";
+      const mm = aBrowser.messageManager;
+      const reply = yield PromiseMessage.send(mm, msgKey);
+      return reply.data.result;
+    }
+  )
+};
+
+function isXULBrowser(aBrowser) {
+  if (!aBrowser || !aBrowser.namespaceURI || !aBrowser.localName) {
+    return false;
+  }
+  const XUL = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";
+  return (aBrowser.namespaceURI === XUL && aBrowser.localName === "browser");
+}
+
+function checkForManifest(aWindow) {
+  // Only top-level browsing contexts are valid.
+  if (!aWindow || aWindow.top !== aWindow) {
+    return false;
+  }
+  const elem = aWindow.document.querySelector("link[rel~='manifest']");
+  // Only if we have an element and a non-empty href attribute.
+  if (!elem || !elem.getAttribute("href")) {
+    return false;
+  }
+  return true;
+}
+
+this.EXPORTED_SYMBOLS = [// jshint ignore:line
+  "ManifestFinder"
+];