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diff --git a/dom/manifest/ManifestObtainer.jsm b/dom/manifest/ManifestObtainer.jsm
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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/.
+ */
+ /*
+ * ManifestObtainer is an implementation of:
+ * http://w3c.github.io/manifest/#obtaining
+ *
+ * Exposes 2 public method:
+ *
+ *  .contentObtainManifest(aContent) - used in content process
+ *  .browserObtainManifest(aBrowser) - used in browser/parent process
+ *
+ * both return a promise. If successful, you get back a manifest object.
+ *
+ * Import it with URL:
+ *   'chrome://global/content/manifestMessages.js'
+ *
+ * e10s IPC message from this components are handled by:
+ *   dom/ipc/manifestMessages.js
+ *
+ * Which is injected into every browser instance via browser.js.
+ *
+ * exported ManifestObtainer
+ */
+/*globals Components, Task, PromiseMessage, XPCOMUtils, ManifestProcessor, BrowserUtils*/
+"use strict";
+const {
+  utils: Cu,
+  classes: Cc,
+  interfaces: Ci
+} = Components;
+Cu.import("resource://gre/modules/Task.jsm");
+Cu.import("resource://gre/modules/PromiseMessage.jsm");
+Cu.import("resource://gre/modules/XPCOMUtils.jsm");
+Cu.import("resource://gre/modules/ManifestProcessor.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "BrowserUtils",  // jshint ignore:line
+  "resource://gre/modules/BrowserUtils.jsm");
+
+this.ManifestObtainer = { // jshint ignore:line
+  /**
+  * Public interface for obtaining a web manifest from a XUL browser, to use
+  * on the parent process.
+  * @param  {XULBrowser} The browser to check for the manifest.
+  * @return {Promise<Object>} The processed manifest.
+  */
+  browserObtainManifest: Task.async(function* (aBrowser) {
+    const msgKey = "DOM:ManifestObtainer:Obtain";
+    if (!isXULBrowser(aBrowser)) {
+      throw new TypeError("Invalid input. Expected XUL browser.");
+    }
+    const mm = aBrowser.messageManager;
+    const {data: {success, result}} = yield PromiseMessage.send(mm, msgKey);
+    if (!success) {
+      const error = toError(result);
+      throw error;
+    }
+    return result;
+  }),
+  /**
+   * Public interface for obtaining a web manifest from a XUL browser.
+   * @param  {Window} The content Window from which to extract the manifest.
+   * @return {Promise<Object>} The processed manifest.
+   */
+  contentObtainManifest: Task.async(function* (aContent) {
+    if (!aContent || isXULBrowser(aContent)) {
+      throw new TypeError("Invalid input. Expected a DOM Window.");
+    }
+    let manifest;
+    try {
+      manifest = yield fetchManifest(aContent);
+    } catch (err) {
+      throw err;
+    }
+    return manifest;
+  }
+)};
+
+function toError(aErrorClone) {
+  let error;
+  switch (aErrorClone.name) {
+  case "TypeError":
+    error = new TypeError();
+    break;
+  default:
+    error = new Error();
+  }
+  Object.getOwnPropertyNames(aErrorClone)
+    .forEach(name => error[name] = aErrorClone[name]);
+  return error;
+}
+
+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");
+}
+
+/**
+ * Asynchronously processes the result of response after having fetched
+ * a manifest.
+ * @param {Response} aResp Response from fetch().
+ * @param {Window} aContentWindow The content window.
+ * @return {Promise<Object>} The processed manifest.
+ */
+const processResponse = Task.async(function* (aResp, aContentWindow) {
+  const badStatus = aResp.status < 200 || aResp.status >= 300;
+  if (aResp.type === "error" || badStatus) {
+    const msg =
+      `Fetch error: ${aResp.status} - ${aResp.statusText} at ${aResp.url}`;
+    throw new Error(msg);
+  }
+  const text = yield aResp.text();
+  const args = {
+    jsonText: text,
+    manifestURL: aResp.url,
+    docURL: aContentWindow.location.href
+  };
+  const manifest = ManifestProcessor.process(args);
+  return manifest;
+});
+
+/**
+ * Asynchronously fetches a web manifest.
+ * @param {Window} a The content Window from where to extract the manifest.
+ * @return {Promise<Object>}
+ */
+const fetchManifest = Task.async(function* (aWindow) {
+  if (!aWindow || aWindow.top !== aWindow) {
+    let msg = "Window must be a top-level browsing context.";
+    throw new Error(msg);
+  }
+  const elem = aWindow.document.querySelector("link[rel~='manifest']");
+  if (!elem || !elem.getAttribute("href")) {
+    let msg = `No manifest to fetch at ${aWindow.location}`;
+    throw new Error(msg);
+  }
+  // Throws on malformed URLs
+  const manifestURL = new aWindow.URL(elem.href, elem.baseURI);
+  const reqInit = {
+    mode: "cors"
+  };
+  if (elem.crossOrigin === "use-credentials") {
+    reqInit.credentials = "include";
+  }
+  const request = new aWindow.Request(manifestURL, reqInit);
+  request.overrideContentPolicyType(Ci.nsIContentPolicy.TYPE_WEB_MANIFEST);
+  let response;
+  try {
+    response = yield aWindow.fetch(request);
+  } catch (err) {
+    throw err;
+  }
+  const manifest = yield processResponse(response, aWindow);
+  return manifest;
+});
+
+this.EXPORTED_SYMBOLS = ["ManifestObtainer"]; // jshint ignore:line