--- a/browser/locales/en-US/chrome/browser/browser.properties
+++ b/browser/locales/en-US/chrome/browser/browser.properties
@@ -439,16 +439,22 @@ dataReportingNotification.button.accessK
 
 # Webapps notification popup
 webapps.install = Install
 webapps.install.accesskey = I
 #LOCALIZATION NOTE (webapps.requestInstall) %1$S is the web app name, %2$S is the site from which the web app is installed
 webapps.requestInstall = Do you want to install "%1$S" from this site (%2$S)?
 webapps.install.success = Application Installed
 webapps.install.inprogress = Installation in progress
+webapps.uninstall = Uninstall
+webapps.uninstall.accesskey = U
+webapps.doNotUninstall = Don't Uninstall
+webapps.doNotUninstall.accesskey = D
+#LOCALIZATION NOTE (webapps.requestUninstall) %1$S is the web app name
+webapps.requestUninstall = Do you want to uninstall "%1$S"?
 
 # LOCALIZATION NOTE (fullscreen.entered): displayed when we enter HTML5 fullscreen mode, %S is the domain name of the focused website (e.g. mozilla.com).
 fullscreen.entered=%S is now fullscreen.
 # LOCALIZATION NOTE (fullscreen.rememberDecision): displayed when we enter HTML5 fullscreen mode, %S is the domain name of the focused website (e.g. mozilla.com).
 fullscreen.rememberDecision=Remember decision for %S
 
 # LOCALIZATION NOTE (fullscreenButton.tooltip): %S is the keyboard shortcut for full screen
 fullscreenButton.tooltip=Display the window in full screen (%S)

--- a/browser/modules/WebappManager.jsm
+++ b/browser/modules/WebappManager.jsm
@@ -26,25 +26,27 @@ XPCOMUtils.defineLazyServiceGetter(this,
                                    "nsIMessageSender");
 
 this.WebappManager = {
   // List of promises for in-progress installations
   installations: {},
 
   init: function() {
     Services.obs.addObserver(this, "webapps-ask-install", false);
+    Services.obs.addObserver(this, "webapps-ask-uninstall", false);
     Services.obs.addObserver(this, "webapps-launch", false);
     Services.obs.addObserver(this, "webapps-uninstall", false);
     cpmm.addMessageListener("Webapps:Install:Return:OK", this);
     cpmm.addMessageListener("Webapps:Install:Return:KO", this);
     cpmm.addMessageListener("Webapps:UpdateState", this);
   },
 
   uninit: function() {
     Services.obs.removeObserver(this, "webapps-ask-install");
+    Services.obs.removeObserver(this, "webapps-ask-uninstall");
     Services.obs.removeObserver(this, "webapps-launch");
     Services.obs.removeObserver(this, "webapps-uninstall");
     cpmm.removeMessageListener("Webapps:Install:Return:OK", this);
     cpmm.removeMessageListener("Webapps:Install:Return:KO", this);
     cpmm.removeMessageListener("Webapps:UpdateState", this);
   },
 
   receiveMessage: function(aMessage) {
@@ -76,23 +78,30 @@ this.WebappManager = {
       this.installations[manifestURL].reject(data.error);
     }
   },
 
   observe: function(aSubject, aTopic, aData) {
     let data = JSON.parse(aData);
     data.mm = aSubject;
 
+    let win;
     switch(aTopic) {
       case "webapps-ask-install":
-        let win = this._getWindowForId(data.oid);
+        win = this._getWindowForId(data.oid);
         if (win && win.location.href == data.from) {
           this.doInstall(data, win);
         }
         break;
+      case "webapps-ask-uninstall":
+        win = this._getWindowForId(data.windowId);
+        if (win && win.location.href == data.from) {
+          this.doUninstall(data, win);
+        }
+        break;
       case "webapps-launch":
         WebappOSUtils.launch(data);
         break;
       case "webapps-uninstall":
         WebappOSUtils.uninstall(data);
         break;
     }
   },
@@ -188,16 +197,59 @@ this.WebappManager = {
                                             [manifest.name, host], 2);
 
     notification = chromeWin.PopupNotifications.show(browser,
                                                      "webapps-install",
                                                      message,
                                                      "webapps-notification-icon",
                                                      mainAction);
 
+  },
+
+  doUninstall: function(aData, aWindow) {
+    let browser = aWindow.QueryInterface(Ci.nsIInterfaceRequestor)
+                         .getInterface(Ci.nsIWebNavigation)
+                         .QueryInterface(Ci.nsIDocShell)
+                         .chromeEventHandler;
+    let chromeDoc = browser.ownerDocument;
+    let chromeWin = chromeDoc.defaultView;
+
+    let bundle = chromeWin.gNavigatorBundle;
+    let jsonManifest = aData.app.manifest;
+
+    let notification;
+
+    let mainAction = {
+      label: bundle.getString("webapps.uninstall"),
+      accessKey: bundle.getString("webapps.uninstall.accesskey"),
+      callback: () => {
+        notification.remove();
+        DOMApplicationRegistry.confirmUninstall(aData);
+      }
+    };
+
+    let secondaryAction = {
+      label: bundle.getString("webapps.doNotUninstall"),
+      accessKey: bundle.getString("webapps.doNotUninstall.accesskey"),
+      callback: () => {
+        notification.remove();
+        DOMApplicationRegistry.denyUninstall(aData, "USER_DECLINED");
+      }
+    };
+
+    let manifest = new ManifestHelper(jsonManifest, aData.app.origin,
+                                      aData.app.manifestURL);
+
+    let message = bundle.getFormattedString("webapps.requestUninstall",
+                                            [manifest.name]);
+
+    notification = chromeWin.PopupNotifications.show(
+                     browser, "webapps-uninstall", message,
+                     "webapps-notification-icon",
+                     mainAction, [secondaryAction]);
   }
 }
 
 function notifyInstallSuccess(aApp, aNativeApp, aBundle) {
   let launcher = {
     observe: function(aSubject, aTopic) {
       if (aTopic == "alertclickcallback") {
         WebappOSUtils.launch(aApp);

--- a/dom/apps/src/Webapps.js
+++ b/dom/apps/src/Webapps.js
@@ -210,16 +210,17 @@ WebappsRegistry.prototype = {
     if (!this.hasMgmtPrivilege) {
       return null;
     }
 
     if (!this._mgmt) {
       let mgmt = Cc["@mozilla.org/webapps/manager;1"]
                    .createInstance(Ci.nsISupports);
       mgmt.wrappedJSObject.init(this._window);
+      mgmt.wrappedJSObject._windowId = this._id;
       this._mgmt = mgmt.__DOM_IMPL__
         ? mgmt.__DOM_IMPL__
         : this._window.DOMApplicationsManager._create(this._window, mgmt.wrappedJSObject);
     }
     return this._mgmt;
   },
 
   uninit: function() {
@@ -716,20 +717,25 @@ WebappsApplicationMgmt.prototype = {
     }
 
     cpmm.sendAsyncMessage("Webapps:ApplyDownload",
                           { manifestURL: aApp.manifestURL });
   },
 
   uninstall: function(aApp) {
     let request = this.createRequest();
-    cpmm.sendAsyncMessage("Webapps:Uninstall", { origin: aApp.origin,
-                                                 manifestURL: aApp.manifestURL,
-                                                 oid: this._id,
-                                                 requestID: this.getRequestId(request) });
+
+    cpmm.sendAsyncMessage("Webapps:Uninstall", {
+      origin: aApp.origin,
+      manifestURL: aApp.manifestURL,
+      oid: this._id,
+      from: this._window.location.href,
+      windowId: this._windowId,
+      requestID: this.getRequestId(request)
+    });
     return request;
   },
 
   getAll: function() {
     let request = this.createRequest();
     let window = this._window;
     DOMApplicationRegistry.getAll((aApps) => {
       Services.DOMRequest.fireSuccessAsync(request,

--- a/dom/apps/src/Webapps.jsm
+++ b/dom/apps/src/Webapps.jsm
@@ -157,16 +157,17 @@ this.DOMApplicationRegistry = {
   get kHostedAppcache() "hosted-appcache",
 
   // Path to the webapps.json file where we store the registry data.
   appsFile: null,
   webapps: { },
   children: [ ],
   allAppsLaunchable: false,
   _updateHandlers: [ ],
+  _pendingUninstalls: {},
 
   init: function() {
     this.messages = ["Webapps:Install", "Webapps:Uninstall",
                      "Webapps:GetSelf", "Webapps:CheckInstalled",
                      "Webapps:GetInstalled", "Webapps:GetNotInstalled",
                      "Webapps:Launch",
                      "Webapps:InstallPackage",
                      "Webapps:GetList", "Webapps:RegisterForMessages",
@@ -542,17 +543,17 @@ this.DOMApplicationRegistry = {
       "https://" + app.manifestURL.substring("http://".length);
 
     // This will uninstall the http apps and remove any data hold by this
     // app. Bug 948105 tracks data migration from http to https apps.
     for (let id in this.webapps) {
        if (this.webapps[id].manifestURL === httpsManifestURL) {
          debug("Found a http/https match: " + app.manifestURL + " / " +
                this.webapps[id].manifestURL);
-         this.uninstall(app.manifestURL, function() {}, function() {});
+         this.uninstall(app.manifestURL);
          return;
        }
     }
 #endif
   },
 
   // Implements the core of bug 787439
   // if at first run, go through these steps:
@@ -2633,17 +2634,17 @@ this.DOMApplicationRegistry = {
       if (supportUseCurrentProfile()) {
         PermissionsInstaller.installPermissions(
           {
             origin: appObject.origin,
             manifestURL: appObject.manifestURL,
             manifest: jsonManifest
           },
           isReinstall,
-          this.uninstall.bind(this, aData, aData.mm)
+          this.doUninstall.bind(this, aData, aData.mm)
         );
       }
 
       this.updateDataStore(this.webapps[id].localId,  this.webapps[id].origin,
                            this.webapps[id].manifestURL, jsonManifest);
     }
 
     for each (let prop in ["installState", "downloadAvailable", "downloading",
@@ -3670,89 +3671,124 @@ this.DOMApplicationRegistry = {
       this.broadcastMessage("Webapps:FireEvent", {
         eventType: "downloaderror",
         manifestURL:  aNewApp.manifestURL
       });
     });
     AppDownloadManager.remove(aNewApp.manifestURL);
   },
 
-  doUninstall: function(aData, aMm) {
-    this.uninstall(aData.manifestURL,
-      function onsuccess() {
-        aMm.sendAsyncMessage("Webapps:Uninstall:Return:OK", aData);
-      },
-      function onfailure() {
-        // Fall-through, fails to uninstall the desired app because:
-        //   - we cannot find the app to be uninstalled.
-        //   - the app to be uninstalled is not removable.
-        aMm.sendAsyncMessage("Webapps:Uninstall:Return:KO", aData);
+  doUninstall: Task.async(function*(aData, aMm) {
+    // The yields here could get stuck forever, so we only hold
+    // a weak reference to the message manager while yielding, to avoid
+    // leaking the whole page associationed with the message manager.
+    aMm = Cu.getWeakReference(aMm);
+
+    let response = "Webapps:Uninstall:Return:OK";
+
+    try {
+      aData.app = yield this._getAppWithManifest(aData.manifestURL);
+
+      let prefName = "dom.mozApps.auto_confirm_uninstall";
+      if (Services.prefs.prefHasUserValue(prefName) &&
+          Services.prefs.getBoolPref(prefName)) {
+        yield this._uninstallApp(aData.app);
+      } else {
+        yield this._promptForUninstall(aData);
       }
-    );
+    } catch (error) {
+      aData.error = error;
+      response = "Webapps:Uninstall:Return:KO";
+    }
+
+    if (aMm = aMm.get()) {
+      aMm.sendAsyncMessage(response, aData);
+    }
+  }),
+
+  uninstall: function(aManifestURL) {
+    return this._getAppWithManifest(aManifestURL)
+      .then(this._uninstallApp.bind(this));
   },
 
-  uninstall: function(aManifestURL, aOnSuccess, aOnFailure) {
-    debug("uninstall " + aManifestURL);
-
-    let app = this.getAppByManifestURL(aManifestURL);
-    if (!app) {
-      aOnFailure("NO_SUCH_APP");
-      return;
+  _uninstallApp: Task.async(function*(aApp) {
+    if (!aApp.removable) {
+      debug("Error: cannot uninstall a non-removable app.");
+      throw new Error("NON_REMOVABLE_APP");
     }
-    let id = app.id;
-
-    if (!app.removable) {
-      debug("Error: cannot uninstall a non-removable app.");
-      aOnFailure("NON_REMOVABLE_APP");
-      return;
-    }
+
+    let id = aApp.id;
 
     // Check if we are downloading something for this app, and cancel the
     // download if needed.
-    this.cancelDownload(app.manifestURL);
+    this.cancelDownload(aApp.manifestURL);
 
     // Clean up the deprecated manifest cache if needed.
     if (id in this._manifestCache) {
       delete this._manifestCache[id];
     }
 
     // Clear private data first.
-    this._clearPrivateData(app.localId, false);
+    this._clearPrivateData(aApp.localId, false);
 
     // Then notify observers.
-    // We have to clone the app object as nsIDOMApplication objects are
-    // stringified as an empty object. (see bug 830376)
-    let appClone = AppsUtils.cloneAppObject(app);
-    Services.obs.notifyObservers(null, "webapps-uninstall", JSON.stringify(appClone));
+    Services.obs.notifyObservers(null, "webapps-uninstall", JSON.stringify(aApp));
 
     if (supportSystemMessages()) {
-      this._readManifests([{ id: id }]).then((aResult) => {
-        this._unregisterActivities(aResult[0].manifest, app);
-      });
+      this._unregisterActivities(aApp.manifest, aApp);
     }
 
     let dir = this._getAppDir(id);
     try {
       dir.remove(true);
     } catch (e) {}
 
     delete this.webapps[id];
 
-    this._saveApps().then(() => {
-      this.broadcastMessage("Webapps:Uninstall:Broadcast:Return:OK", appClone);
-      this.broadcastMessage("Webapps:RemoveApp", { id: id });
-      try {
-        if (aOnSuccess) {
-          aOnSuccess();
-        }
-      } catch(ex) {
-        Cu.reportError("DOMApplicationRegistry: Exception on app uninstall: " +
-                       ex + "\n" + ex.stack);
-      }
-    });
+    yield this._saveApps();
+
+    this.broadcastMessage("Webapps:Uninstall:Broadcast:Return:OK", aApp);
+    this.broadcastMessage("Webapps:RemoveApp", { id: id });
+
+    return aApp;
+  }),
+
+  _promptForUninstall: function(aData) {
+    let deferred = Promise.defer();
+    this._pendingUninstalls[aData.requestID] = deferred;
+    Services.obs.notifyObservers(null, "webapps-ask-uninstall",
+                                 JSON.stringify(aData));
+    return deferred.promise;
+  },
+
+  confirmUninstall: function(aData) {
+    let pending = this._pendingUninstalls[aData.requestID];
+    if (pending) {
+      delete this._pendingUninstalls[aData.requestID];
+      return this._uninstallApp(aData.app).then(() => {
+        pending.resolve();
+        return aData.app;
+      });
+    }
+    return Promise.reject(new Error("PENDING_UNINSTALL_NOT_FOUND"));
+  },
+
+  denyUninstall: function(aData, aReason = "ERROR_UNKNOWN_FAILURE") {
+    // Fails to uninstall the desired app because:
+    //   - we cannot find the app to be uninstalled.
+    //   - the app to be uninstalled is not removable.
+    //   - the user declined the confirmation
+    debug("Failed to uninstall app: " + aReason);
+    let pending = this._pendingUninstalls[aData.requestID];
+    if (pending) {
+      delete this._pendingUninstalls[aData.requestID];
+      pending.reject(new Error(aReason));
+      return Promise.resolve();
+    }
+    return Promise.reject(new Error("PENDING_UNINSTALL_NOT_FOUND"));
   },
 
   getSelf: function(aData, aMm) {
     aData.apps = [];
 
     if (aData.appId == Ci.nsIScriptSecurityManager.NO_APP_ID ||
         aData.appId == Ci.nsIScriptSecurityManager.UNKNOWN_APP_ID) {
       aMm.sendAsyncMessage("Webapps:GetSelf:Return:OK", aData);
@@ -4062,16 +4098,27 @@ this.DOMApplicationRegistry = {
       return aResult[0].manifest;
     });
   },
 
   getAppByManifestURL: function(aManifestURL) {
     return AppsUtils.getAppByManifestURL(this.webapps, aManifestURL);
   },
 
+  _getAppWithManifest: Task.async(function*(aManifestURL) {
+    let app = this.getAppByManifestURL(aManifestURL);
+    if (!app) {
+      throw new Error("NO_SUCH_APP");
+    }
+
+    app.manifest = ( yield this._readManifests([{ id: app.id }]) )[0].manifest;
+
+    return app;
+  }),
+
   getCSPByLocalId: function(aLocalId) {
     debug("getCSPByLocalId:" + aLocalId);
     return AppsUtils.getCSPByLocalId(this.webapps, aLocalId);
   },
 
   getAppLocalIdByStoreId: function(aStoreId) {
     debug("getAppLocalIdByStoreId:" + aStoreId);
     return AppsUtils.getAppLocalIdByStoreId(this.webapps, aStoreId);

--- a/webapprt/WebappManager.jsm
+++ b/webapprt/WebappManager.jsm
@@ -14,26 +14,33 @@ Cu.import("resource://gre/modules/XPCOMU
 Cu.import("resource://gre/modules/Services.jsm");
 Cu.import("resource://gre/modules/Webapps.jsm");
 Cu.import("resource://gre/modules/AppsUtils.jsm");
 Cu.import("resource://gre/modules/NativeApp.jsm");
 Cu.import("resource://gre/modules/WebappOSUtils.jsm");
 Cu.import("resource://webapprt/modules/WebappRT.jsm");
 
 this.WebappManager = {
-  observe: function(subject, topic, data) {
-    data = JSON.parse(data);
-    data.mm = subject;
+  observe: function(aSubject, aTopic, aData) {
+    let data = JSON.parse(aData);
+    data.mm = aSubject;
 
-    switch (topic) {
+    let chromeWin;
+    switch (aTopic) {
       case "webapps-ask-install":
-        let chromeWin = Services.wm.getOuterWindowWithId(data.oid);
+        chromeWin = Services.wm.getOuterWindowWithId(data.oid);
         if (chromeWin)
           this.doInstall(data, chromeWin);
         break;
+      case "webapps-ask-uninstall":
+        chromeWin = Services.wm.getOuterWindowWithId(data.windowId);
+        if (chromeWin) {
+          this.doUninstall(data, chromeWin);
+        }
+        break;
       case "webapps-launch":
         WebappOSUtils.launch(data);
         break;
       case "webapps-uninstall":
         WebappOSUtils.uninstall(data);
         break;
     }
   },
@@ -70,32 +77,64 @@ this.WebappManager = {
     if (choice == 0) {
       let nativeApp = new NativeApp(data.app, jsonManifest,
                                     data.app.categories,
                                     WebappRT.config.registryDir);
       let localDir;
       try {
         localDir = nativeApp.createProfile();
       } catch (ex) {
-        DOMApplicationRegistry.denyInstall(aData);
+        DOMApplicationRegistry.denyInstall(data);
         return;
       }
 
       DOMApplicationRegistry.confirmInstall(data, localDir,
         Task.async(function*(aApp, aManifest, aZipPath) {
           yield nativeApp.install(aApp, aManifest, aZipPath);
         })
       );
     } else {
       DOMApplicationRegistry.denyInstall(data);
     }
   },
 
+  doUninstall: function(aData, aWindow) {
+    let jsonManifest = aData.isPackage ? aData.app.updateManifest : aData.app.manifest;
+    let manifest = new ManifestHelper(jsonManifest, aData.app.origin,
+                                      aData.app.manifestURL);
+    let name = manifest.name;
+    let bundle = Services.strings.createBundle("chrome://webapprt/locale/webapp.properties");
+
+    let choice = Services.prompt.confirmEx(
+      aWindow,
+      bundle.formatStringFromName("webapps.uninstall.title", [name], 1),
+      bundle.formatStringFromName("webapps.uninstall.description", [name], 1),
+      // Set both buttons to strings with the cancel button being default
+      Ci.nsIPromptService.BUTTON_POS_1_DEFAULT |
+        Ci.nsIPromptService.BUTTON_TITLE_IS_STRING * Ci.nsIPromptService.BUTTON_POS_0 |
+        Ci.nsIPromptService.BUTTON_TITLE_IS_STRING * Ci.nsIPromptService.BUTTON_POS_1,
+      bundle.GetStringFromName("webapps.uninstall.uninstall"),
+      bundle.GetStringFromName("webapps.uninstall.dontuninstall"),
+      null,
+      null,
+      {});
+
+    // Perform the uninstall if the user allows it
+    if (choice == 0) {
+      DOMApplicationRegistry.confirmUninstall(aData).then((aApp) => {
+        WebappOSUtils.uninstall(aApp);
+      });
+    } else {
+      DOMApplicationRegistry.denyUninstall(aData);
+    }
+  },
+
   QueryInterface: XPCOMUtils.generateQI([Ci.nsIObserver,
                                          Ci.nsISupportsWeakReference])
 };
 
 Services.obs.addObserver(WebappManager, "webapps-ask-install", false);
+Services.obs.addObserver(WebappManager, "webapps-ask-uninstall", false);
 Services.obs.addObserver(WebappManager, "webapps-launch", false);
 Services.obs.addObserver(WebappManager, "webapps-uninstall", false);
 Services.obs.addObserver(WebappManager, "webapps-update", false);
 
 DOMApplicationRegistry.registerUpdateHandler(WebappManager.update);

--- a/webapprt/locales/en-US/webapprt/webapp.properties
+++ b/webapprt/locales/en-US/webapprt/webapp.properties
@@ -35,11 +35,19 @@ desktop-notification.remember=Remember m
 # LOCALIZATION NOTE (webapps.install.title): %S will be replaced with the name
 # of the webapp being installed.
 webapps.install.title=Install %S
 # LOCALIZATION NOTE (webapps.install.description): %S will be replaced with the
 # name of the webapp being installed.
 webapps.install.description=Do you want to install %S?
 webapps.install.install=Install App
 webapps.install.dontinstall=Don't Install
+# LOCALIZATION NOTE (webapps.uninstall.title): %S will be replaced with the name
+# of the webapp being uninstalled.
+webapps.uninstall.title=Uninstall %S
+# LOCALIZATION NOTE (webapps.uninstall.description): %S will be replaced with the
+# name of the webapp being uninstalled.
+webapps.uninstall.description=Do you want to uninstall %S?
+webapps.uninstall.uninstall=Uninstall App
+webapps.uninstall.dontuninstall=Don't Uninstall
 
 paymentDialog.title=Payment
 paymentDialog.message=Which payment provider do you want to use?