diff --git a/content/base/public/nsIFrameLoader.idl b/content/base/public/nsIFrameLoader.idl
index 9f3c21c27784..4e91d82e3511 100644
--- a/content/base/public/nsIFrameLoader.idl
+++ b/content/base/public/nsIFrameLoader.idl
@@ -288,6 +288,7 @@ interface nsIFrameLoader : nsISupports
 
   /**
    * Find out whether the owner content really is a browser or app frame
+   * Especially, a widget frame is regarded as an app frame.
    */
   readonly attribute boolean ownerIsBrowserOrAppFrame;
 };
diff --git a/content/base/src/nsGkAtomList.h b/content/base/src/nsGkAtomList.h
index 561a628e36f1..c3c9d9a0ab8b 100644
--- a/content/base/src/nsGkAtomList.h
+++ b/content/base/src/nsGkAtomList.h
@@ -91,6 +91,7 @@ GK_ATOM(_and, "and")
 GK_ATOM(anonid, "anonid")
 GK_ATOM(any, "any")
 GK_ATOM(mozapp, "mozapp")
+GK_ATOM(mozwidget, "mozwidget")
 GK_ATOM(applet, "applet")
 GK_ATOM(applyImports, "apply-imports")
 GK_ATOM(applyTemplates, "apply-templates")
diff --git a/content/html/content/src/nsGenericHTMLFrameElement.cpp b/content/html/content/src/nsGenericHTMLFrameElement.cpp
index e700f01c0e0b..a015675c7264 100644
--- a/content/html/content/src/nsGenericHTMLFrameElement.cpp
+++ b/content/html/content/src/nsGenericHTMLFrameElement.cpp
@@ -332,6 +332,63 @@ nsGenericHTMLFrameElement::GetIsExpectingSystemMessage(bool *aOut)
   return NS_OK;
 }
 
+/** Get manifest url of app or widget
+ * @param AppType: nsGkAtoms::mozapp or nsGkAtoms::mozwidget
+ */
+void nsGenericHTMLFrameElement::GetManifestURLByType(nsIAtom *aAppType,
+                                                     nsAString& aManifestURL)
+{
+  aManifestURL.Truncate();
+
+  if (aAppType != nsGkAtoms::mozapp && aAppType != nsGkAtoms::mozwidget) {
+    return;
+  }
+
+  nsAutoString manifestURL;
+  GetAttr(kNameSpaceID_None, aAppType, manifestURL);
+  if (manifestURL.IsEmpty()) {
+    return;
+  }
+
+  // Check permission.
+  nsCOMPtr<nsIPermissionManager> permMgr = services::GetPermissionManager();
+  NS_ENSURE_TRUE_VOID(permMgr);
+  nsIPrincipal *principal = NodePrincipal();
+  const char* aPermissionType = (aAppType == nsGkAtoms::mozapp) ? "embed-apps"
+                                                                : "embed-widgets";
+  uint32_t permission = nsIPermissionManager::DENY_ACTION;
+  nsresult rv = permMgr->TestPermissionFromPrincipal(principal,
+                                                     aPermissionType,
+                                                     &permission);
+  NS_ENSURE_SUCCESS_VOID(rv);
+  if (permission != nsIPermissionManager::ALLOW_ACTION) {
+    return;
+  }
+
+  nsCOMPtr<nsIAppsService> appsService = do_GetService(APPS_SERVICE_CONTRACTID);
+  NS_ENSURE_TRUE_VOID(appsService);
+
+  nsCOMPtr<mozIApplication> app;
+  appsService->GetAppByManifestURL(manifestURL, getter_AddRefs(app));
+
+  if (!app) {
+    return;
+  }
+
+  bool hasWidgetPage = false;
+  nsAutoString src;
+  if (aAppType == nsGkAtoms::mozwidget) {
+    GetAttr(kNameSpaceID_None, nsGkAtoms::src, src);
+    nsresult rv = app->HasWidgetPage(src, &hasWidgetPage);
+
+    if (!NS_SUCCEEDED(rv) || !hasWidgetPage) {
+      return;
+    }
+  }
+
+  aManifestURL.Assign(manifestURL);
+}
+
 NS_IMETHODIMP
 nsGenericHTMLFrameElement::GetAppManifestURL(nsAString& aOut)
 {
@@ -342,35 +399,36 @@ nsGenericHTMLFrameElement::GetAppManifestURL(nsAString& aOut)
     return NS_OK;
   }
 
-  // Check permission.
-  nsIPrincipal *principal = NodePrincipal();
-  nsCOMPtr<nsIPermissionManager> permMgr =
-    services::GetPermissionManager();
-  NS_ENSURE_TRUE(permMgr, NS_OK);
+  nsAutoString appManifestURL;
+  nsAutoString widgetManifestURL;
 
-  uint32_t permission = nsIPermissionManager::DENY_ACTION;
-  nsresult rv = permMgr->TestPermissionFromPrincipal(principal,
-                                                     "embed-apps",
-                                                     &permission);
-  NS_ENSURE_SUCCESS(rv, NS_OK);
-  if (permission != nsIPermissionManager::ALLOW_ACTION) {
+  GetManifestURLByType(nsGkAtoms::mozapp, appManifestURL);
+
+  if (Preferences::GetBool("dom.enable_widgets")) {
+    GetManifestURLByType(nsGkAtoms::mozwidget, widgetManifestURL);
+  }
+
+  bool isApp = !appManifestURL.IsEmpty();
+  bool isWidget = !widgetManifestURL.IsEmpty();
+
+  if (!isApp && !isWidget) {
+    // No valid case to get manifest
+    return NS_OK;
+  }
+
+  if (isApp && isWidget) {
+    NS_WARNING("Can not simultaneously be mozapp and mozwidget");
     return NS_OK;
   }
 
   nsAutoString manifestURL;
-  GetAttr(kNameSpaceID_None, nsGkAtoms::mozapp, manifestURL);
-  if (manifestURL.IsEmpty()) {
-    return NS_OK;
+  if (isApp) {
+    manifestURL.Assign(appManifestURL);
+  } else if (isWidget) {
+    manifestURL.Assign(widgetManifestURL);
   }
 
-  nsCOMPtr<nsIAppsService> appsService = do_GetService(APPS_SERVICE_CONTRACTID);
-  NS_ENSURE_TRUE(appsService, NS_OK);
-
-  nsCOMPtr<mozIApplication> app;
-  appsService->GetAppByManifestURL(manifestURL, getter_AddRefs(app));
-  if (app) {
-    aOut.Assign(manifestURL);
-  }
+  aOut.Assign(manifestURL);
 
   return NS_OK;
 }
diff --git a/content/html/content/src/nsGenericHTMLFrameElement.h b/content/html/content/src/nsGenericHTMLFrameElement.h
index 8f7386e916df..de3fe18a3936 100644
--- a/content/html/content/src/nsGenericHTMLFrameElement.h
+++ b/content/html/content/src/nsGenericHTMLFrameElement.h
@@ -88,6 +88,9 @@ protected:
   {
     return this;
   }
+
+private:
+  void GetManifestURLByType(nsIAtom *aAppType, nsAString& aOut);
 };
 
 #endif // nsGenericHTMLFrameElement_h
diff --git a/dom/apps/src/AppsUtils.jsm b/dom/apps/src/AppsUtils.jsm
index 097a00b1b501..c903387b7340 100644
--- a/dom/apps/src/AppsUtils.jsm
+++ b/dom/apps/src/AppsUtils.jsm
@@ -57,6 +57,10 @@ mozIApplication.prototype = {
     return (perm === Ci.nsIPermissionManager.ALLOW_ACTION);
   },
 
+  hasWidgetPage: function(aPageURL) {
+    return this.widgetPages.indexOf(aPageURL) != -1;
+  },
+
   QueryInterface: function(aIID) {
     if (aIID.equals(Ci.mozIApplication) ||
         aIID.equals(Ci.nsISupports))
@@ -100,6 +104,7 @@ function _setAppProperties(aObj, aApp) {
   aObj.storeVersion = aApp.storeVersion || 0;
   aObj.role = aApp.role || "";
   aObj.redirects = aApp.redirects;
+  aObj.widgetPages = aApp.widgetPages || [];
   aObj.kind = aApp.kind;
 }
 
@@ -678,6 +683,10 @@ ManifestHelper.prototype = {
     return this._localeProp("package_path");
   },
 
+  get widgetPages() {
+    return this._localeProp("widgetPages");
+  },
+
   get size() {
     return this._manifest["size"] || 0;
   },
diff --git a/dom/apps/src/PermissionsTable.jsm b/dom/apps/src/PermissionsTable.jsm
index dfed59b8efd8..2b09c8277f63 100644
--- a/dom/apps/src/PermissionsTable.jsm
+++ b/dom/apps/src/PermissionsTable.jsm
@@ -232,6 +232,11 @@ this.PermissionsTable =  { geolocation: {
                              privileged: DENY_ACTION,
                              certified: ALLOW_ACTION
                            },
+                           "embed-widgets": {
+                             app: DENY_ACTION,
+                             privileged: ALLOW_ACTION,
+                             certified: ALLOW_ACTION
+                           },
                            "storage": {
                              app: ALLOW_ACTION,
                              privileged: ALLOW_ACTION,
diff --git a/dom/apps/src/Webapps.jsm b/dom/apps/src/Webapps.jsm
index d92f14fbc0d5..f9a35e6c4888 100755
--- a/dom/apps/src/Webapps.jsm
+++ b/dom/apps/src/Webapps.jsm
@@ -262,6 +262,10 @@ this.DOMApplicationRegistry = {
           app.role = "";
         }
 
+        if (app.widgetPages === undefined) {
+          app.widgetPages = [];
+        }
+
         // At startup we can't be downloading, and the $TMP directory
         // will be empty so we can't just apply a staged update.
         app.downloading = false;
@@ -321,6 +325,15 @@ this.DOMApplicationRegistry = {
     return res.length > 0 ? res : null;
   },
 
+  _saveWidgetsFullPath: function(aManifest, aDestApp) {
+    if (aManifest.widgetPages) {
+      aDestApp.widgetPages = aManifest.widgetPages.map(aManifest.resolveURL,
+                                                       aManifest/* thisArg */);
+    } else {
+      aDestApp.widgetPages = [];
+    }
+  },
+
   // Registers all the activities and system messages.
   registerAppsHandlers: Task.async(function*(aRunUpdate) {
     this.notifyAppsRegistryStart();
@@ -345,6 +358,10 @@ this.DOMApplicationRegistry = {
         let app = this.webapps[aResult.id];
         app.csp = aResult.manifest.csp || "";
         app.role = aResult.manifest.role || "";
+
+        let localeManifest = new ManifestHelper(aResult.manifest, app.origin, app.manifestURL);
+        this._saveWidgetsFullPath(localeManifest, app);
+
         if (app.appStatus >= Ci.nsIPrincipal.APP_STATUS_PRIVILEGED) {
           app.redirects = this.sanitizeRedirects(aResult.redirects);
         }
@@ -984,6 +1001,8 @@ this.DOMApplicationRegistry = {
         app.name = manifest.name;
         app.csp = manifest.csp || "";
         app.role = localeManifest.role;
+        this._saveWidgetsFullPath(localeManifest, app);
+
         if (app.appStatus >= Ci.nsIPrincipal.APP_STATUS_PRIVILEGED) {
           app.redirects = this.sanitizeRedirects(manifest.redirects);
         }
@@ -2014,6 +2033,8 @@ this.DOMApplicationRegistry = {
     aApp.downloadAvailable = true;
     aApp.downloadSize = manifest.size;
     aApp.updateManifest = aNewManifest;
+    this._saveWidgetsFullPath(manifest, aApp);
+
     yield this._saveApps();
 
     this.broadcastMessage("Webapps:UpdateState", {
@@ -2072,6 +2093,7 @@ this.DOMApplicationRegistry = {
       aApp.name = aNewManifest.name;
       aApp.csp = manifest.csp || "";
       aApp.role = manifest.role || "";
+      this._saveWidgetsFullPath(manifest, aApp);
       aApp.updateTime = Date.now();
     } else {
       manifest =
@@ -2471,6 +2493,7 @@ this.DOMApplicationRegistry = {
     appObject.name = aManifest.name;
     appObject.csp = aLocaleManifest.csp || "";
     appObject.role = aLocaleManifest.role;
+    this._saveWidgetsFullPath(aLocaleManifest, appObject);
     appObject.installerAppId = aData.appId;
     appObject.installerIsBrowser = aData.isBrowser;
 
@@ -2506,6 +2529,9 @@ this.DOMApplicationRegistry = {
 
     app.csp = aManifest.csp || "";
 
+    let aLocaleManifest = new ManifestHelper(aManifest, app.origin, app.manifestURL);
+    this._saveWidgetsFullPath(aLocaleManifest, app);
+
     app.appStatus = AppsUtils.getAppManifestStatus(aManifest);
 
     app.removable = true;
diff --git a/dom/apps/tests/file_app.sjs b/dom/apps/tests/file_app.sjs
index fe6164724d09..cef10bd3ae3e 100644
--- a/dom/apps/tests/file_app.sjs
+++ b/dom/apps/tests/file_app.sjs
@@ -1,6 +1,7 @@
 var gBasePath = "tests/dom/apps/tests/";
 var gAppTemplatePath = "tests/dom/apps/tests/file_app.template.html";
 var gAppcacheTemplatePath = "tests/dom/apps/tests/file_cached_app.template.appcache";
+var gWidgetTemplatePath = "tests/dom/apps/tests/file_widget_app.template.html";
 var gDefaultIcon = "default_icon";
 
 function makeResource(templatePath, version, apptype) {
@@ -14,7 +15,6 @@ function makeResource(templatePath, version, apptype) {
   if (templatePath == gAppTemplatePath && apptype == 'cached') {
     res = res.replace('<html>', '<html manifest="file_app.sjs?apptype=cached&getappcache=true">');
   }
-
   return res;
 }
 
@@ -46,7 +46,7 @@ function handleRequest(request, response) {
 
   // Get the app type.
   var apptype = query.apptype;
-  if (apptype != 'hosted' && apptype != 'cached')
+  if (apptype != 'hosted' && apptype != 'cached' && apptype != 'widget')
     throw "Invalid app type: " + apptype;
 
   // Get the version from server state and handle the etag.
@@ -83,7 +83,12 @@ function handleRequest(request, response) {
     response.write(makeResource(gAppcacheTemplatePath, version, apptype));
     return;
   }
-
+  else if (apptype == 'widget')
+  {
+    response.setHeader("Content-Type", "text/html", false);
+    response.write(makeResource(gWidgetTemplatePath, version, apptype));
+    return;
+  }
   // Generate the app.
   response.setHeader("Content-Type", "text/html", false);
   response.write(makeResource(gAppTemplatePath, version, apptype));
diff --git a/dom/apps/tests/file_widget_app.template.html b/dom/apps/tests/file_widget_app.template.html
new file mode 100644
index 000000000000..661e2c5d8a0c
--- /dev/null
+++ b/dom/apps/tests/file_widget_app.template.html
@@ -0,0 +1,68 @@
+<html>
+<head>
+<script>
+
+function sendMessage(msg) {
+  alert(msg);
+}
+
+function ok(p, msg) {
+  if (p)
+    sendMessage("OK: " + msg);
+  else
+    sendMessage("KO: " + msg);
+}
+
+function is(a, b, msg) {
+  if (a == b)
+    sendMessage("OK: " + a + " == " + b + " - " + msg);
+  else
+    sendMessage("KO: " + a + " != " + b + " - " + msg);
+}
+
+function installed(p) {
+  if (p)
+    sendMessage("IS_INSTALLED");
+  else
+    sendMessage("NOT_INSTALLED");
+}
+
+function finish() {
+  sendMessage("VERSION: MyWebApp vVERSIONTOKEN");
+  sendMessage("DONE");
+}
+
+function cbError() {
+  ok(false, "Error callback invoked");
+  finish();
+}
+
+function go() {
+  ok(true, "Launched app");
+  var request = window.navigator.mozApps.getSelf();
+  request.onsuccess = function() {
+    var widget = request.result;
+    ok(widget,"Should be a widget");
+    checkWidget(widget);
+  }
+  request.onerror = cbError;
+}
+
+function checkWidget(widget) {
+  // If the widget is installed, |widget| will be non-null. If it is, verify its state.
+  installed(!!widget);
+  if (widget) {
+    var widgetName = "Really Rapid Release (APPTYPETOKEN)";
+    var manifest = SpecialPowers.wrap(widget.manifest);
+    is(manifest.name, widgetName, "Manifest name should be correct");
+    is(widget.origin, "http://test", "Widget origin should be correct");
+    is(widget.installOrigin, "http://mochi.test:8888", "Install origin should be correct");
+  }
+  finish();
+}
+
+</script>
+</head>
+<body onload="go();">
+App Body. Version: VERSIONTOKEN
+</body></html>
diff --git a/dom/apps/tests/file_widget_app.template.webapp b/dom/apps/tests/file_widget_app.template.webapp
new file mode 100644
index 000000000000..7990043392fa
--- /dev/null
+++ b/dom/apps/tests/file_widget_app.template.webapp
@@ -0,0 +1,11 @@
+{
+  "name": "Really Rapid Release (widget)",
+  "description": "Updated even faster than <a href='http://mozilla.org'>Firefox</a>, just to annoy slashdotters.",
+  "launch_path": "/tests/dom/apps/tests/file_app.sjs?apptype=widget",
+  "icons": {
+    "128": "ICONTOKEN"
+  },
+  "widgetPages": [
+    "/tests/dom/apps/tests/file_app.sjs?apptype=widget"
+  ]
+}
diff --git a/dom/apps/tests/mochitest.ini b/dom/apps/tests/mochitest.ini
index 8b67d343d118..e5f55fd78c2d 100644
--- a/dom/apps/tests/mochitest.ini
+++ b/dom/apps/tests/mochitest.ini
@@ -10,6 +10,8 @@ support-files =
   file_packaged_app.sjs
   file_packaged_app.template.html
   file_packaged_app.template.webapp
+  file_widget_app.template.webapp
+  file_widget_app.template.html
   signed_app.sjs
   signed_app_template.webapp
   signed/*
@@ -28,3 +30,4 @@ skip-if = buildapp == "b2g" || toolkit == "android" # see bug 989806
 [test_receipt_operations.html]
 [test_signed_pkg_install.html]
 [test_uninstall_errors.html]
+[test_widget.html]
diff --git a/dom/apps/tests/test_widget.html b/dom/apps/tests/test_widget.html
new file mode 100644
index 000000000000..a4292c0a58df
--- /dev/null
+++ b/dom/apps/tests/test_widget.html
@@ -0,0 +1,127 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>Test for DataStore - basic operation on a readonly db</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<div id="container"></div>
+  <script type="application/javascript;version=1.7">
+
+  var gWidgetManifestURL = 'http://test/tests/dom/apps/tests/file_app.sjs?apptype=widget&getmanifest=true';
+  var gApp;
+
+  function cbError() {
+    ok(false, "Error callback invoked");
+    finish();
+  }
+
+  function installApp() {
+    var request = navigator.mozApps.install(gWidgetManifestURL);
+    request.onerror = cbError;
+    request.onsuccess = function() {
+      gApp = request.result;
+
+      runTest();
+    }
+  }
+
+  function uninstallApp() {
+    // Uninstall the app.
+    var request = navigator.mozApps.mgmt.uninstall(gApp);
+    request.onerror = cbError;
+    request.onsuccess = function() {
+      // All done.
+      info("All done");
+      runTest();
+    }
+  }
+
+  function testApp() {
+    var ifr = document.createElement('iframe');
+    ifr.setAttribute('mozbrowser', 'true');
+    ifr.setAttribute('mozwidget', gApp.manifestURL);
+    ifr.setAttribute('src', gApp.origin+gApp.manifest.launch_path);
+
+    var domParent = document.getElementById('container');
+
+    // Set us up to listen for messages from the app.
+    var listener = function(e) {
+      var message = e.detail.message;
+      if (/^OK/.exec(message)) {
+        ok(true, "Message from widget: " + message);
+      } else if (/KO/.exec(message)) {
+        ok(false, "Message from widget: " + message);
+      } else if (/DONE/.exec(message)) {
+        ok(true, "Message from widget complete");
+        ifr.removeEventListener('mozbrowsershowmodalprompt', listener);
+        domParent.removeChild(ifr);
+        runTest();
+      }
+    }
+
+    // This event is triggered when the app calls "alert".
+    ifr.addEventListener('mozbrowsershowmodalprompt', listener, false);
+    domParent.appendChild(ifr);
+  }
+
+  var tests = [
+    // Permissions
+    function() {
+      SpecialPowers.pushPermissions(
+        [{ "type": "browser", "allow": 1, "context": document },
+         { "type": "embed-widgets", "allow": 1, "context": document },
+         { "type": "webapps-manage", "allow": 1, "context": document }], runTest);
+    },
+
+    // Preferences
+    function() {
+      SpecialPowers.pushPrefEnv({"set": [["dom.mozBrowserFramesEnabled", true],
+                                         ["dom.enable_widgets", true]]}, runTest);
+    },
+
+    function() {
+      SpecialPowers.setAllAppsLaunchable(true);
+      runTest();
+    },
+
+    // No confirmation needed when an app is installed
+    function() {
+      SpecialPowers.autoConfirmAppInstall(runTest);
+    },
+
+    // Installing the app
+    installApp,
+
+    // Run tests in app
+    testApp,
+
+    // Uninstall the app
+    uninstallApp
+  ];
+
+  function runTest() {
+    if (!tests.length) {
+      finish();
+      return;
+    }
+
+    var test = tests.shift();
+    test();
+  }
+
+  function finish() {
+    SimpleTest.finish();
+  }
+
+  if (SpecialPowers.isMainProcess()) {
+    SpecialPowers.Cu.import("resource://gre/modules/DataStoreChangeNotifier.jsm");
+  }
+
+  SimpleTest.waitForExplicitFinish();
+  runTest();
+  </script>
+</body>
+</html>
diff --git a/dom/interfaces/apps/mozIApplication.idl b/dom/interfaces/apps/mozIApplication.idl
index ddc7c99797a1..4dfc6e68e07d 100644
--- a/dom/interfaces/apps/mozIApplication.idl
+++ b/dom/interfaces/apps/mozIApplication.idl
@@ -11,12 +11,18 @@
  * We expose Gecko-internal helpers related to "web apps" through this
  * sub-interface.
  */
-[scriptable, uuid(7bd62430-c374-49eb-be1b-ce821a180360)]
+[scriptable, uuid(1d856b11-ac29-47d3-bd52-a86e3d45fcf4)]
 interface mozIApplication: nsISupports
 {
   /* Return true if this app has |permission|. */
   boolean hasPermission(in string permission);
 
+  /**
+   *  Return true if this app can be a widget and
+   *  its |widgetPages| contains |page|
+   */
+  boolean hasWidgetPage(in DOMString pageURL);
+
   /* Application status as defined in nsIPrincipal. */
   readonly attribute unsigned short appStatus;
 
diff --git a/dom/interfaces/html/nsIMozBrowserFrame.idl b/dom/interfaces/html/nsIMozBrowserFrame.idl
index fedbec09333c..19783e1fa52b 100644
--- a/dom/interfaces/html/nsIMozBrowserFrame.idl
+++ b/dom/interfaces/html/nsIMozBrowserFrame.idl
@@ -25,8 +25,11 @@ interface nsIMozBrowserFrame : nsIDOMMozBrowserFrame
    * Gets whether this frame really is an app frame.
    *
    * In order to really be an app frame, this frame must really be a browser
-   * frame (this requirement will go away eventually), and the frame's mozapp
-   * attribute must point to the manifest of a valid app.
+   * frame (this requirement will go away eventually), and must satisfy one
+   * and only one of the following conditions:
+   * 1. the frame's mozapp attribute must point to the manifest of a valid app
+   * 2. the frame's mozwidget attribute must point to the manifest of a valid
+   * app, and the src should be in the |widgetPages| specified by the manifest.
    */
   [infallible] readonly attribute boolean reallyIsApp;
 
@@ -41,7 +44,8 @@ interface nsIMozBrowserFrame : nsIDOMMozBrowserFrame
   [infallible] readonly attribute boolean isExpectingSystemMessage;
 
   /**
-   * Gets this frame's app manifest URL, if the frame really is an app frame.
+   * Gets this frame's app manifest URL or widget manifest URL, if the frame
+   * really is an app frame.
    * Otherwise, returns the empty string.
    *
    * This method is guaranteed not to fail.