--- a/dom/apps/tests/file_packaged_app.sjs
+++ b/dom/apps/tests/file_packaged_app.sjs
@@ -15,33 +15,45 @@ var gMiniManifestTemplate = "file_packag
 var gAppTemplate = "file_packaged_app.template.html";
 var gAppName = "appname";
 var gDevName = "devname";
 var gDevUrl = "http://dev.url";
 
 function handleRequest(request, response) {
   var query = getQuery(request);
 
-  response.setHeader("Access-Control-Allow-Origin", "*", false);
-
   var packageSize = ("packageSize" in query) ? query.packageSize : 0;
   var appName = ("appName" in query) ? query.appName : gAppName;
   var devName = ("devName" in query) ? query.devName : gDevName;
   var devUrl = ("devUrl" in query) ? query.devUrl : gDevUrl;
+  // allowCancel just means deliver the file slowly so we have time to cancel it
+  var allowCancel = "allowCancel" in query;
+  var getPackage = "getPackage" in query;
+  var alreadyDeferred = Number(getState("alreadyDeferred"));
+
+  if (allowCancel && getPackage && !alreadyDeferred) {
+    // Only do this for the actual package delivery.
+    response.processAsync();
+    // And to avoid timer problems, only do this once.
+    setState("alreadyDeferred", "1");
+  }
+
+  response.setHeader("Access-Control-Allow-Origin", "*", false);
 
   // If this is a version update, update state, prepare the manifest,
   // the application package and return.
   if ("setVersion" in query) {
     var version = query.setVersion;
     setState("version", version);
     var packageVersion = ("dontUpdatePackage" in query) ? version - 1 : version;
     var packageName = "test_packaged_app_" + packageVersion + ".zip";
 
     setState("packageName", packageName);
-    var packagePath = "/" + gBasePath + "file_packaged_app.sjs?getPackage=" +
+    var packagePath = "/" + gBasePath + "file_packaged_app.sjs?" +
+                      (allowCancel?"allowCancel&": "") + "getPackage=" +
                       packageName;
     setState("packagePath", packagePath);
 
     if (version == packageVersion) {
       // Create the application package.
       var zipWriter = Cc["@mozilla.org/zipwriter;1"]
                         .createInstance(Ci.nsIZipWriter);
       var zipFile = FileUtils.getFile("TmpD", [packageName]);
@@ -79,21 +91,29 @@ function handleRequest(request, response
     dump("Etags Match. Sending 304\n");
     response.setStatusLine(request.httpVersion, "304", "Not modified");
     return;
   }
 
   response.setHeader("Etag", etag, false);
 
   // Serve the application package corresponding to the requested app version.
-  if ("getPackage" in query) {
+  if (getPackage) {
     var resource = readFile(packageName, true);
     response.setHeader("Content-Type",
                        "Content-Type: application/java-archive", false);
-    response.write(resource);
+    if (allowCancel && !alreadyDeferred) {
+      var timer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
+      timer.initWithCallback(function (aTimer) {
+          response.write(resource);
+          response.finish();
+      }, 3000, Ci.nsITimer.TYPE_ONE_SHOT);
+    } else {
+      response.write(resource);
+    }
     return;
   }
 
   // Serve the mini-manifest corresponding to the requested app version.
   if ("getManifest" in query) {
     var template = gBasePath + gMiniManifestTemplate;
     if (!("noManifestContentType" in query)) {
       response.setHeader("Content-Type",

--- a/dom/apps/tests/test_packaged_app_common.js
+++ b/dom/apps/tests/test_packaged_app_common.js
@@ -52,23 +52,27 @@ var PackagedTestHelper = (function Packa
     finish();
   }
 
   function xhrAbort(url) {
     ok(false, "XHR abort loading " + url);
     finish();
   }
 
-  function setAppVersion(aVersion, aCb, aDontUpdatePackage) {
+  function setAppVersion(aVersion, aCb, aDontUpdatePackage, aAllowCancel) {
     var xhr = new XMLHttpRequest();
     var dontUpdate = "";
+    var allowCancel = "";
     if (aDontUpdatePackage) {
       dontUpdate = "&dontUpdatePackage=1";
     }
-    var url = gSJS + "?setVersion=" + aVersion + dontUpdate;
+    if (aAllowCancel) {
+      allowCancel= "&allowCancel=1";
+    }
+    var url = gSJS + "?setVersion=" + aVersion + dontUpdate + allowCancel;
     xhr.addEventListener("load", function() {
                            is(xhr.responseText, "OK", "setAppVersion OK");
                            aCb();
                          });
     xhr.addEventListener("error", event => xhrError(event, url));
     xhr.addEventListener("abort", event => xhrAbort(url));
     xhr.open("GET", url, true);
     xhr.send();

--- a/dom/apps/tests/test_packaged_app_install.html
+++ b/dom/apps/tests/test_packaged_app_install.html
@@ -29,29 +29,29 @@ function checkAppInstallError(aMiniManif
   var req = navigator.mozApps.installPackage(aMiniManifestURL);
   req.onsuccess = function() {
     ok(false, "We are supposed to throw " + aExpectedError);
     PackagedTestHelper.finish();
   };
   req.onerror = function(evt) {
     var error = evt.target.error.name;
     if (error == aExpectedError) {
-      ok(true, "Got expected " + aExpectedError);
+      info("Got expected " + aExpectedError);
       PackagedTestHelper.next();
     } else {
       ok(false, "Got unexpected " + error);
       PackagedTestHelper.finish();
     }
   };
 }
 
 function checkUninstallApp(aApp) {
   var req = navigator.mozApps.mgmt.uninstall(aApp);
   req.onsuccess = function() {
-    ok(true, "App uninstalled");
+    info("App uninstalled");
     aApp.ondownloadsuccess = null;
     aApp.ondownloaderror = null;
     aApp.onprogress = null;
     PackagedTestHelper.next();
   };
   req.onerror = function(evt) {
     ok(false, "Got unexpected " + evt.target.error.name);
     PackagedTestHelper.finish();
@@ -78,84 +78,84 @@ function checkInstalledApp(aMiniManifest
 
 SimpleTest.waitForExplicitFinish();
 
 var steps = [
   function() {
     // Set up
     SpecialPowers.setAllAppsLaunchable(true);
     SpecialPowers.addPermission("webapps-manage", true, document);
-    ok(true, "Set up");
+    info("Set up");
     PackagedTestHelper.next();
   },
   function() {
-    ok(true, "autoConfirmAppInstall");
+    info("autoConfirmAppInstall");
     SpecialPowers.autoConfirmAppInstall(PackagedTestHelper.next);
   },
   function() {
     PackagedTestHelper.setAppVersion(0, PackagedTestHelper.next);
   },
   function() {
     // Bug 927699 - navigator.mozApps.install(url) lets NS_ERROR_FAILURE onto
     //              the web.
-    ok(true, "== TEST == INVALID_URL");
+    info("== TEST == INVALID_URL");
     checkAppInstallError("", "INVALID_URL");
   },
   function() {
     // Test network error.
-    ok(true, "== TEST == Network error");
+    info("== TEST == Network error");
     checkAppInstallError("http://notvalidurl", "NETWORK_ERROR");
   },
   function() {
     // Test wrong mini-manifest content type.
-    ok(true, "== TEST == Not valid mini-manifest content type");
+    info("== TEST == Not valid mini-manifest content type");
     var miniManifestURL = PackagedTestHelper.gSJS +
                           "?getManifest=true" +
                           "&noManifestContentType=true";
     checkAppInstallError(miniManifestURL, "INVALID_MANIFEST_CONTENT_TYPE");
   },
   function() {
     // Test mini-manifest 'size' value is not number. Bug 839435.
-    ok(true, "== TEST == Size value is not a number");
+    info("== TEST == Size value is not a number");
     var miniManifestURL = PackagedTestHelper.gSJS +
                           "?getManifest=true" +
                           "&packageSize=\"NotANumber\"";
     checkAppInstallError(miniManifestURL, "INVALID_MANIFEST");
   },
   function() {
     // Test mini-manifest  negative 'size' value. Bug 839435.
-    ok(true, "== TEST == Negative size value");
+    info("== TEST == Negative size value");
     var miniManifestURL = PackagedTestHelper.gSJS +
                           "?getManifest=true" +
                           "&packageSize=-1";
     checkAppInstallError(miniManifestURL, "INVALID_MANIFEST");
   },
   function() {
     // Test wrong package path
-    ok(true, "== TEST == Installing app with wrong package path");
+    info("== TEST == Installing app with wrong package path");
     var miniManifestURL = PackagedTestHelper.gSJS +
                           "?getManifest=true" +
                           "&wrongPackagePath=true";
     checkAppInstallError(miniManifestURL, "INVALID_MANIFEST");
   },
   function() {
     // Test no manifest in zip file.
-    ok(true, "== TEST == No manifest in the zip file");
+    info("== TEST == No manifest in the zip file");
     var miniManifestURL = PackagedTestHelper.gSJS + "?getManifest=true";
     PackagedTestHelper.checkAppDownloadError(miniManifestURL,
                                             "MISSING_MANIFEST", 0, true, true,
                                              PackagedTestHelper.gAppName);
   },
   function() {
       PackagedTestHelper.setAppVersion(1, PackagedTestHelper.next);
   },
   function() {
     // Test mini-manifest app name is different from the webapp manifest name.
     // Bug 844243.
-    ok(true, "== TEST == Mini-manifest app name is different from webapp " +
+    info("== TEST == Mini-manifest app name is different from webapp " +
              "manifest name");
     var miniManifestURL = PackagedTestHelper.gSJS +
                           "?getManifest=true" +
                           "&appName=arandomname";
     PackagedTestHelper.checkAppDownloadError(miniManifestURL,
                                              "MANIFEST_MISMATCH", 1, true, true,
                                              "arandomname");
   },
@@ -182,29 +182,29 @@ var steps = [
     PackagedTestHelper.checkAppDownloadError(miniManifestURL,
                                              "MANIFEST_MISMATCH", 1, true, true,
                                              PackagedTestHelper.gAppName);
   },
   function() {
     PackagedTestHelper.setAppVersion(2, PackagedTestHelper.next);
   },
   function() {
-    ok(true, "== TEST == Install packaged app");
+    info("== TEST == Install packaged app");
     var miniManifestURL = PackagedTestHelper.gSJS +
                           "?getManifest=true";
     navigator.mozApps.mgmt.oninstall = function(evt) {
-      ok(true, "Got oninstall event");
+      info("Got oninstall event");
       PackagedTestHelper.gApp = evt.application;
       PackagedTestHelper.gApp.ondownloaderror = function() {
         ok(false, "Download error " +
                   PackagedTestHelper.gApp.downloadError.name);
         PackagedTestHelper.finish();
       };
       PackagedTestHelper.gApp.ondownloadsuccess = function() {
-        ok(true, "App downloaded");
+        info("App downloaded");
         var expected = {
           name: PackagedTestHelper.gAppName,
           manifestURL: miniManifestURL,
           installOrigin: PackagedTestHelper.gInstallOrigin,
           progress: 0,
           installState: "installed",
           downloadAvailable: false,
           downloading: false,
@@ -215,21 +215,95 @@ var steps = [
         PackagedTestHelper.checkAppState(PackagedTestHelper.gApp, 2, expected,
                                          true, false, PackagedTestHelper.next);
       };
     };
 
     var request = navigator.mozApps.installPackage(miniManifestURL);
     request.onerror = PackagedTestHelper.mozAppsError;
     request.onsuccess = function() {
-      ok(true, "Application installed");
+      info("Application installed");
     };
   },
   function() {
-    ok(true, "all done!\n");
+    PackagedTestHelper.setAppVersion(3, PackagedTestHelper.next, false, true);
+  },
+  function() {
+    info("== TEST == Install packaged app with a cancel/resume");
+    var miniManifestURL = PackagedTestHelper.gSJS +
+                          "?getManifest=true&allowCancel";
+    navigator.mozApps.mgmt.oninstall = function(evt) {
+      info("Got oninstall event");
+      PackagedTestHelper.gApp = evt.application;
+
+      PackagedTestHelper.gApp.onprogress = function() {
+        // Let's try cancelling and resuming the download later on.
+        PackagedTestHelper.gApp.cancelDownload();
+        // And only do this once.
+        PackagedTestHelper.gApp.onprogress = null;
+      };
+
+      var alreadyCancelled = false;
+      PackagedTestHelper.gApp.ondownloaderror = function() {
+        ok(!alreadyCancelled, "The download should be cancelled only once!");
+        is(PackagedTestHelper.gApp.downloadError.name, "DOWNLOAD_CANCELED",
+           "Download error " + PackagedTestHelper.gApp.downloadError.name);
+        if (!alreadyCancelled) {
+          PackagedTestHelper.gApp.download();
+          alreadyCancelled = true;
+        }
+      };
+
+      PackagedTestHelper.gApp.ondownloadsuccess = function() {
+        info("App downloaded");
+        // We could try also applying the download we just made.
+        var expected = {
+          name: PackagedTestHelper.gAppName,
+          manifestURL: miniManifestURL,
+          installOrigin: PackagedTestHelper.gInstallOrigin,
+          progress: 0,
+          installState: "pending",
+          downloadAvailable: false,
+          downloading: false,
+          downloadSize: 0,
+          size: 0,
+          readyToApplyDownload: true
+        };
+        PackagedTestHelper.checkAppState(PackagedTestHelper.gApp, 3, expected,
+                                         true, false, function() {});
+      };
+
+      PackagedTestHelper.gApp.ondownloadapplied = function() {
+        info("App download applied.");
+        var expected = {
+          name: PackagedTestHelper.gAppName,
+          manifestURL: miniManifestURL,
+          installOrigin: PackagedTestHelper.gInstallOrigin,
+          progress: 0,
+          installState: "installed",
+          downloadAvailable: false,
+          downloading: false,
+          downloadSize: 0,
+          size: 0,
+          readyToApplyDownload: false
+        };
+        PackagedTestHelper.checkAppState(PackagedTestHelper.gApp, 3, expected,
+                                         true, false, PackagedTestHelper.next);
+      }
+
+    };
+
+    var request = navigator.mozApps.installPackage(miniManifestURL);
+    request.onerror = PackagedTestHelper.mozAppsError;
+    request.onsuccess = function() {
+      info("Application installed");
+    };
+  },
+  function() {
+    info("all done!\n");
     PackagedTestHelper.finish();
   }
 ];
 
 PackagedTestHelper.setSteps(steps);
 
 addLoadEvent(PackagedTestHelper.start);