diff --git a/dom/apps/src/AppsUtils.jsm b/dom/apps/src/AppsUtils.jsm
index 4ab81234fed0..4882cb8d5d24 100644
--- a/dom/apps/src/AppsUtils.jsm
+++ b/dom/apps/src/AppsUtils.jsm
@@ -93,6 +93,7 @@ this.AppsUtils = {
       installerIsBrowser: !!aApp.installerIsBrowser,
       storeId: aApp.storeId || "",
       storeVersion: aApp.storeVersion || 0,
+      role: aApp.role || "",
       redirects: aApp.redirects
     };
   },
@@ -320,6 +321,10 @@ this.AppsUtils = {
       }
     }
 
+    // The 'role' field must be a string.
+    if (aManifest.role && (typeof aManifest.role !== "string")) {
+      return false;
+    }
     return true;
   },
 
@@ -639,5 +644,9 @@ ManifestHelper.prototype = {
   fullPackagePath: function() {
     let packagePath = this._localeProp("package_path");
     return this._origin.resolve(packagePath ? packagePath : "");
+  },
+
+  get role() {
+    return this._manifest.role || "";
   }
 }
diff --git a/dom/apps/src/Webapps.jsm b/dom/apps/src/Webapps.jsm
index 0f5a8382f5aa..cec1ea66c205 100644
--- a/dom/apps/src/Webapps.jsm
+++ b/dom/apps/src/Webapps.jsm
@@ -190,6 +190,11 @@ this.DOMApplicationRegistry = {
               this.webapps[id].storeVersion = 0;
             }
 
+            // Default role to "".
+            if (this.webapps[id].role === undefined) {
+              this.webapps[id].role = "";
+            }
+
             // 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;
@@ -242,13 +247,14 @@ this.DOMApplicationRegistry = {
     if (supportSystemMessages()) {
       this._processManifestForIds(ids, aRunUpdate);
     } else {
-      // Read the CSPs. If MOZ_SYS_MSG is defined this is done on
+      // Read the CSPs and roles. If MOZ_SYS_MSG is defined this is done on
       // _processManifestForIds so as to not reading the manifests
       // twice
       this._readManifests(ids, (function readCSPs(aResults) {
         aResults.forEach(function registerManifest(aResult) {
           let app = this.webapps[aResult.id];
           app.csp = aResult.manifest.csp || "";
+          app.role = aResult.manifest.role || "";
           if (app.appStatus >= Ci.nsIPrincipal.APP_STATUS_PRIVILEGED) {
             app.redirects = this.sanitizeRedirects(aResult.redirects);
           }
@@ -734,6 +740,7 @@ this.DOMApplicationRegistry = {
         let manifest = aResult.manifest;
         app.name = manifest.name;
         app.csp = manifest.csp || "";
+        app.role = manifest.role || "";
         if (app.appStatus >= Ci.nsIPrincipal.APP_STATUS_PRIVILEGED) {
           app.redirects = this.sanitizeRedirects(manifest.redirects);
         }
@@ -1477,6 +1484,7 @@ this.DOMApplicationRegistry = {
 
         app.name = manifest.name;
         app.csp = manifest.csp || "";
+        app.role = manifest.role || "";
         app.updateTime = Date.now();
       } else {
         manifest = new ManifestHelper(aOldManifest, app.origin);
@@ -2057,6 +2065,7 @@ this.DOMApplicationRegistry = {
 
     appObject.name = manifest.name;
     appObject.csp = manifest.csp || "";
+    appObject.role = manifest.role || "";
 
     appObject.installerAppId = aData.appId;
     appObject.installerIsBrowser = aData.isBrowser;
diff --git a/dom/interfaces/apps/mozIApplication.idl b/dom/interfaces/apps/mozIApplication.idl
index 458f59713300..8438e769b1aa 100644
--- a/dom/interfaces/apps/mozIApplication.idl
+++ b/dom/interfaces/apps/mozIApplication.idl
@@ -11,7 +11,7 @@
  * We expose Gecko-internal helpers related to "web apps" through this
  * sub-interface.
  */
-[scriptable, uuid(05c57885-27cf-47fc-8da7-eeec9eb853a7)]
+[scriptable, uuid(11322d0c-e98e-442d-97a6-8b197d5b888e)]
 interface mozIApplication: mozIDOMApplication
 {
   /* Return true if this app has |permission|. */
@@ -40,4 +40,7 @@ interface mozIApplication: mozIDOMApplication
 
   /* Store version if the app is installed from a store */
   readonly attribute unsigned long storeVersion;
+
+  /* role copied from the manifest */
+  readonly attribute DOMString role;
 };