Added more typechecking functions and unit tests for existing code.

This change alters the functionality of getObjectAttr slightly: it no
longer accepts null or Array objects as "object" values.  I made this
change because the type checking code seems designed to mirror the
semantics of JSON, where each value belongs to exactly one of the
following categories: array, boolean, number, null, object, or string.

This change also changes the type of values thrown from strings to Error objects so that there are more likely to be useful stack traces when an error occurs.

BUG=

Review URL: https://codereview.chromium.org/1015553003

Cr-Commit-Position: refs/heads/master@{#321415}

remoting/remoting_webapp_files.gypi

@@ -77,6 +77,7 @@
       'webapp/crd/js/identity_unittest.js',
       'webapp/crd/js/l10n_unittest.js',
       'webapp/crd/js/menu_button_unittest.js',
+      'webapp/crd/js/typecheck_unittest.js',
       'webapp/crd/js/xhr_unittest.js',
       'webapp/crd/js/xmpp_connection_unittest.js',
       'webapp/crd/js/xmpp_login_handler_unittest.js',

remoting/webapp/app_remoting/js/app_remoting.js

@@ -315,7 +315,7 @@ remoting.AppRemoting.prototype.onExtensionMessage = function(type, message) {
     case 'openURL':
       // URL requests from the hosted app are untrusted, so disallow anything
       // other than HTTP or HTTPS.
-      var url = getStringAttr(message, 'url');
+      var url = base.getStringAttr(message, 'url');
       if (url.indexOf('http:') != 0 && url.indexOf('https:') != 0) {
         console.error('Bad URL: ' + url);
       } else {
@@ -324,13 +324,13 @@ remoting.AppRemoting.prototype.onExtensionMessage = function(type, message) {
       return true;
 
     case 'onWindowRemoved':
-      var id = getNumberAttr(message, 'id');
+      var id = base.getNumberAttr(message, 'id');
       this.windowActivationMenu_.remove(id);
       return true;
 
     case 'onWindowAdded':
-      var id = getNumberAttr(message, 'id');
-      var title = getStringAttr(message, 'title');
+      var id = base.getNumberAttr(message, 'id');
+      var title = base.getStringAttr(message, 'title');
       this.windowActivationMenu_.add(id, title);
       return true;
 
@@ -339,15 +339,15 @@ remoting.AppRemoting.prototype.onExtensionMessage = function(type, message) {
       return true;
 
     case 'setKeyboardLayouts':
-      var supportedLayouts = getArrayAttr(message, 'supportedLayouts');
-      var currentLayout = getStringAttr(message, 'currentLayout');
+      var supportedLayouts = base.getArrayAttr(message, 'supportedLayouts');
+      var currentLayout = base.getStringAttr(message, 'currentLayout');
       console.log('Current host keyboard layout: ' + currentLayout);
       console.log('Supported host keyboard layouts: ' + supportedLayouts);
       this.keyboardLayoutsMenu_.setLayouts(supportedLayouts, currentLayout);
       return true;
 
     case 'pingResponse':
-      var then = getNumberAttr(message, 'timestamp');
+      var then = base.getNumberAttr(message, 'timestamp');
       var now = new Date().getTime();
       this.contextMenu_.updateConnectionRTT(now - then);
       return true;

remoting/webapp/base/js/base.js

@@ -34,7 +34,6 @@ base.debug.assert = function(expr, opt_msg) {
     if (opt_msg) {
       msg += ' ' + opt_msg;
     }
-    console.error(msg);
     if (base.debug.breakOnAssert) {
       alert(msg);
       debugger;

remoting/webapp/crd/js/cast_extension_handler.js

@@ -251,7 +251,7 @@ remoting.CastExtensionHandler.prototype.chromotingMessageListener =
     function(ns, message) {
   if (ns === this.kCastNamespace_) {
     try {
-        var messageObj = getJsonObjectFromString(message);
+        var messageObj = base.getJsonObjectFromString(message);
         this.sendMessageToHost_(messageObj);
     } catch (err) {
       console.error('Failed to process message from Cast device.');

remoting/webapp/crd/js/client_plugin_host_desktop_impl.js

@@ -86,10 +86,10 @@ remoting.ClientPlugin.HostDesktopImpl.prototype.resize = function(
  */
 remoting.ClientPlugin.HostDesktopImpl.prototype.onSizeUpdated = function(
     message) {
-  this.width_ = getNumberAttr(message.data, 'width');
-  this.height_ = getNumberAttr(message.data, 'height');
-  this.xDpi_ = getNumberAttr(message.data, 'x_dpi', 96);
-  this.yDpi_ = getNumberAttr(message.data, 'y_dpi', 96);
+  this.width_ = base.getNumberAttr(message.data, 'width');
+  this.height_ = base.getNumberAttr(message.data, 'height');
+  this.xDpi_ = base.getNumberAttr(message.data, 'x_dpi', 96);
+  this.yDpi_ = base.getNumberAttr(message.data, 'y_dpi', 96);
   this.raiseEvent(remoting.HostDesktop.Events.sizeChanged,
                   this.getDimensions());
 };
@@ -104,7 +104,7 @@ remoting.ClientPlugin.HostDesktopImpl.prototype.onSizeUpdated = function(
  */
 remoting.ClientPlugin.HostDesktopImpl.prototype.onShapeUpdated =
     function(message) {
-  var shapes = getArrayAttr(message.data, 'rects');
+  var shapes = base.getArrayAttr(message.data, 'rects');
   var rects = shapes.map(
     /** @param {Array.<number>} shape */
     function(shape) {

remoting/webapp/crd/js/client_plugin_impl.js

@@ -212,35 +212,36 @@ remoting.ClientPluginImpl.prototype.handleMessageMethod_ = function(message) {
     var handler = this.connectionEventHandler_;
 
     if (message.method == 'sendOutgoingIq') {
-      handler.onOutgoingIq(getStringAttr(message.data, 'iq'));
+      handler.onOutgoingIq(base.getStringAttr(message.data, 'iq'));
 
     } else if (message.method == 'logDebugMessage') {
-      handler.onDebugMessage(getStringAttr(message.data, 'message'));
+      handler.onDebugMessage(base.getStringAttr(message.data, 'message'));
 
     } else if (message.method == 'onConnectionStatus') {
       var state = remoting.ClientSession.State.fromString(
-          getStringAttr(message.data, 'state'));
+          base.getStringAttr(message.data, 'state'));
       var error = remoting.ClientSession.ConnectionError.fromString(
-          getStringAttr(message.data, 'error'));
+          base.getStringAttr(message.data, 'error'));
       handler.onConnectionStatusUpdate(state, error);
 
     } else if (message.method == 'onRouteChanged') {
-      var channel = getStringAttr(message.data, 'channel');
-      var connectionType = getStringAttr(message.data, 'connectionType');
+      var channel = base.getStringAttr(message.data, 'channel');
+      var connectionType = base.getStringAttr(message.data, 'connectionType');
       handler.onRouteChanged(channel, connectionType);
 
     } else if (message.method == 'onConnectionReady') {
-      var ready = getBooleanAttr(message.data, 'ready');
+      var ready = base.getBooleanAttr(message.data, 'ready');
       handler.onConnectionReady(ready);
 
     } else if (message.method == 'setCapabilities') {
       /** @type {!Array<string>} */
-      var capabilities = tokenize(getStringAttr(message.data, 'capabilities'));
+      var capabilities = tokenize(
+          base.getStringAttr(message.data, 'capabilities'));
       handler.onSetCapabilities(capabilities);
 
     } else if (message.method == 'extensionMessage') {
-      var extMsgType = getStringAttr(message.data, 'type');
-      var extMsgData = getStringAttr(message.data, 'data');
+      var extMsgType = base.getStringAttr(message.data, 'type');
+      var extMsgData = base.getStringAttr(message.data, 'data');
       handler.onExtensionMessage(extMsgType, extMsgData);
     }
   }
@@ -248,19 +249,20 @@ remoting.ClientPluginImpl.prototype.handleMessageMethod_ = function(message) {
   if (message.method == 'hello') {
     // Resize in case we had to enlarge it to support click-to-play.
     this.hidePluginForClickToPlay_();
-    this.pluginApiVersion_ = getNumberAttr(message.data, 'apiVersion');
-    this.pluginApiMinVersion_ = getNumberAttr(message.data, 'apiMinVersion');
+    this.pluginApiVersion_ = base.getNumberAttr(message.data, 'apiVersion');
+    this.pluginApiMinVersion_ =
+        base.getNumberAttr(message.data, 'apiMinVersion');
 
     if (this.pluginApiVersion_ >= 7) {
       this.pluginApiFeatures_ =
-          tokenize(getStringAttr(message.data, 'apiFeatures'));
+          tokenize(base.getStringAttr(message.data, 'apiFeatures'));
 
       // Negotiate capabilities.
       /** @type {!Array<string>} */
       var supportedCapabilities = [];
       if ('supportedCapabilities' in message.data) {
         supportedCapabilities =
-            tokenize(getStringAttr(message.data, 'supportedCapabilities'));
+            tokenize(base.getStringAttr(message.data, 'supportedCapabilities'));
       }
       // At the moment the webapp does not recognize any of
       // 'requestedCapabilities' capabilities (so they all should be disabled)
@@ -287,19 +289,19 @@ remoting.ClientPluginImpl.prototype.handleMessageMethod_ = function(message) {
   } else if (message.method == 'onPerfStats') {
     // Return value is ignored. These calls will throw an error if the value
     // is not a number.
-    getNumberAttr(message.data, 'videoBandwidth');
-    getNumberAttr(message.data, 'videoFrameRate');
-    getNumberAttr(message.data, 'captureLatency');
-    getNumberAttr(message.data, 'encodeLatency');
-    getNumberAttr(message.data, 'decodeLatency');
-    getNumberAttr(message.data, 'renderLatency');
-    getNumberAttr(message.data, 'roundtripLatency');
+    base.getNumberAttr(message.data, 'videoBandwidth');
+    base.getNumberAttr(message.data, 'videoFrameRate');
+    base.getNumberAttr(message.data, 'captureLatency');
+    base.getNumberAttr(message.data, 'encodeLatency');
+    base.getNumberAttr(message.data, 'decodeLatency');
+    base.getNumberAttr(message.data, 'renderLatency');
+    base.getNumberAttr(message.data, 'roundtripLatency');
     this.perfStats_ =
         /** @type {remoting.ClientSession.PerfStats} */ (message.data);
 
   } else if (message.method == 'injectClipboardItem') {
-    var mimetype = getStringAttr(message.data, 'mimeType');
-    var item = getStringAttr(message.data, 'item');
+    var mimetype = base.getStringAttr(message.data, 'mimeType');
+    var item = base.getStringAttr(message.data, 'item');
     if (remoting.clipboard) {
       remoting.clipboard.fromHost(mimetype, item);
     }
@@ -313,33 +315,33 @@ remoting.ClientPluginImpl.prototype.handleMessageMethod_ = function(message) {
     // The pairingSupported value in the dictionary indicates whether both
     // client and host support pairing. If the client doesn't support pairing,
     // then the value won't be there at all, so give it a default of false.
-    var pairingSupported = getBooleanAttr(message.data, 'pairingSupported',
+    var pairingSupported = base.getBooleanAttr(message.data, 'pairingSupported',
                                           false);
     this.credentials_.getPIN(pairingSupported).then(
         this.onPinFetched_.bind(this)
     );
 
   } else if (message.method == 'fetchThirdPartyToken') {
-    var tokenUrl = getStringAttr(message.data, 'tokenUrl');
-    var hostPublicKey = getStringAttr(message.data, 'hostPublicKey');
-    var scope = getStringAttr(message.data, 'scope');
+    var tokenUrl = base.getStringAttr(message.data, 'tokenUrl');
+    var hostPublicKey = base.getStringAttr(message.data, 'hostPublicKey');
+    var scope = base.getStringAttr(message.data, 'scope');
     this.credentials_.getThirdPartyToken(tokenUrl, hostPublicKey, scope).then(
       this.onThirdPartyTokenFetched_.bind(this)
     );
   } else if (message.method == 'pairingResponse') {
-    var clientId = getStringAttr(message.data, 'clientId');
-    var sharedSecret = getStringAttr(message.data, 'sharedSecret');
+    var clientId = base.getStringAttr(message.data, 'clientId');
+    var sharedSecret = base.getStringAttr(message.data, 'sharedSecret');
     this.onPairingComplete_(clientId, sharedSecret);
 
   } else if (message.method == 'unsetCursorShape') {
     this.updateMouseCursorImage_('', 0, 0);
 
   } else if (message.method == 'setCursorShape') {
-    var width = getNumberAttr(message.data, 'width');
-    var height = getNumberAttr(message.data, 'height');
-    var hotspotX = getNumberAttr(message.data, 'hotspotX');
-    var hotspotY = getNumberAttr(message.data, 'hotspotY');
-    var srcArrayBuffer = getObjectAttr(message.data, 'data');
+    var width = base.getNumberAttr(message.data, 'width');
+    var height = base.getNumberAttr(message.data, 'height');
+    var hotspotX = base.getNumberAttr(message.data, 'hotspotX');
+    var hotspotY = base.getNumberAttr(message.data, 'hotspotY');
+    var srcArrayBuffer = base.getObjectAttr(message.data, 'data');
 
     var canvas =
         /** @type {HTMLCanvasElement} */ (document.createElement('canvas'));

remoting/webapp/crd/js/gnubby_auth_handler.js

@@ -62,12 +62,12 @@ remoting.GnubbyAuthHandler.prototype.sendMessageToHost_ = function(data) {
  */
 remoting.GnubbyAuthHandler.prototype.onExtensionMessage =
     function(type, message) {
-  var messageType = getStringAttr(message, 'type');
+  var messageType = base.getStringAttr(message, 'type');
   if (messageType == 'data') {
     this.sendMessageToGnubbyd_({
       'type': 'auth-agent@openssh.com',
-      'data': getArrayAttr(message, 'data')
-    }, this.callback_.bind(this, getNumberAttr(message, 'connectionId')));
+      'data': base.getArrayAttr(message, 'data')
+    }, this.callback_.bind(this, base.getNumberAttr(message, 'connectionId')));
   } else {
     console.error('Invalid gnubby-auth message: ' + messageType);
     return false;
@@ -87,7 +87,7 @@ remoting.GnubbyAuthHandler.prototype.callback_ =
     this.sendMessageToHost_({
       'type': 'data',
       'connectionId': connectionId,
-      'data': getArrayAttr(response, 'data')
+      'data': base.getArrayAttr(response, 'data')
     });
   } catch (/** @type {*} */ err) {
     console.error('gnubby callback failed: ', err);

remoting/webapp/crd/js/host.js

@@ -86,13 +86,13 @@ remoting.Host.Options.prototype.load = function() {
       // TODO(kelvinp): Uses a separate host options for app-remoting that
       // hardcodes resizeToClient to true.
       that.resizeToClient =
-          getBooleanAttr(options, 'resizeToClient', true);
-      that.shrinkToFit = getBooleanAttr(options, 'shrinkToFit', true);
-      that.desktopScale = getNumberAttr(options, 'desktopScale', 1);
-      that.remapKeys = getStringAttr(options, 'remapKeys', '');
+          base.getBooleanAttr(options, 'resizeToClient', true);
+      that.shrinkToFit = base.getBooleanAttr(options, 'shrinkToFit', true);
+      that.desktopScale = base.getNumberAttr(options, 'desktopScale', 1);
+      that.remapKeys = base.getStringAttr(options, 'remapKeys', '');
       that.pairingInfo =
           /** @type {remoting.PairingInfo} */ (
-              getObjectAttr(options, 'pairingInfo', that.pairingInfo));
+              base.getObjectAttr(options, 'pairingInfo', that.pairingInfo));
     });
 };
 

remoting/webapp/crd/js/host_daemon_facade.js

@@ -199,7 +199,7 @@ remoting.HostDaemonFacade.prototype.onIncomingMessage_ = function(message) {
   delete this.pendingReplies_[id];
 
   try {
-    var type = getStringAttr(message, 'type');
+    var type = base.getStringAttr(message, 'type');
     if (type != reply.type) {
       throw 'Expected reply type: ' + reply.type + ', got: ' + type;
     }
@@ -222,58 +222,59 @@ remoting.HostDaemonFacade.prototype.onIncomingMessage_ = function(message) {
  */
 remoting.HostDaemonFacade.prototype.handleIncomingMessage_ =
     function(message, onDone) {
-  var type = getStringAttr(message, 'type');
+  var type = base.getStringAttr(message, 'type');
 
   switch (type) {
     case 'helloResponse':
-      this.version_ = getStringAttr(message, 'version');
+      this.version_ = base.getStringAttr(message, 'version');
       // Old versions of the native messaging host do not return this list.
       // Those versions default to the empty list of supported features.
-      this.supportedFeatures_ = getArrayAttr(message, 'supportedFeatures', []);
+      this.supportedFeatures_ =
+          base.getArrayAttr(message, 'supportedFeatures', []);
       onDone();
       break;
 
     case 'getHostNameResponse':
-      onDone(getStringAttr(message, 'hostname'));
+      onDone(base.getStringAttr(message, 'hostname'));
       break;
 
     case 'getPinHashResponse':
-      onDone(getStringAttr(message, 'hash'));
+      onDone(base.getStringAttr(message, 'hash'));
       break;
 
     case 'generateKeyPairResponse':
-      var privateKey = getStringAttr(message, 'privateKey');
-      var publicKey = getStringAttr(message, 'publicKey');
+      var privateKey = base.getStringAttr(message, 'privateKey');
+      var publicKey = base.getStringAttr(message, 'publicKey');
       onDone(privateKey, publicKey);
       break;
 
     case 'updateDaemonConfigResponse':
       var result = remoting.HostController.AsyncResult.fromString(
-          getStringAttr(message, 'result'));
+          base.getStringAttr(message, 'result'));
       onDone(result);
       break;
 
     case 'getDaemonConfigResponse':
-      onDone(getObjectAttr(message, 'config'));
+      onDone(base.getObjectAttr(message, 'config'));
       break;
 
     case 'getUsageStatsConsentResponse':
-      var supported = getBooleanAttr(message, 'supported');
-      var allowed = getBooleanAttr(message, 'allowed');
-      var setByPolicy = getBooleanAttr(message, 'setByPolicy');
+      var supported = base.getBooleanAttr(message, 'supported');
+      var allowed = base.getBooleanAttr(message, 'allowed');
+      var setByPolicy = base.getBooleanAttr(message, 'setByPolicy');
       onDone(supported, allowed, setByPolicy);
       break;
 
     case 'startDaemonResponse':
     case 'stopDaemonResponse':
       var result = remoting.HostController.AsyncResult.fromString(
-          getStringAttr(message, 'result'));
+          base.getStringAttr(message, 'result'));
       onDone(result);
       break;
 
     case 'getDaemonStateResponse':
       var state = remoting.HostController.State.fromString(
-        getStringAttr(message, 'state'));
+        base.getStringAttr(message, 'state'));
       onDone(state);
       break;
 
@@ -289,16 +290,16 @@ remoting.HostDaemonFacade.prototype.handleIncomingMessage_ =
 
     case 'clearPairedClientsResponse':
     case 'deletePairedClientResponse':
-      onDone(getBooleanAttr(message, 'result'));
+      onDone(base.getBooleanAttr(message, 'result'));
       break;
 
     case 'getHostClientIdResponse':
-      onDone(getStringAttr(message, 'clientId'));
+      onDone(base.getStringAttr(message, 'clientId'));
       break;
 
     case 'getCredentialsFromAuthCodeResponse':
-      var userEmail = getStringAttr(message, 'userEmail');
-      var refreshToken = getStringAttr(message, 'refreshToken');
+      var userEmail = base.getStringAttr(message, 'userEmail');
+      var refreshToken = base.getStringAttr(message, 'refreshToken');
       if (userEmail && refreshToken) {
         onDone(userEmail, refreshToken);
       } else {

remoting/webapp/crd/js/host_list_api_impl.js

@@ -118,15 +118,17 @@ remoting.HostListApiImpl.prototype.parseHostListResponse_ =
       var hosts = items.map(
         function(/** Object */ item) {
           var host = new remoting.Host();
-          host.hostName = getStringAttr(item, 'hostName', '');
-          host.hostId = getStringAttr(item, 'hostId', '');
-          host.status = getStringAttr(item, 'status', '');
-          host.jabberId = getStringAttr(item, 'jabberId', '');
-          host.publicKey = getStringAttr(item, 'publicKey', '');
-          host.hostVersion = getStringAttr(item, 'hostVersion', '');
-          host.tokenUrlPatterns = getArrayAttr(item, 'tokenUrlPatterns', []);
-          host.updatedTime = getStringAttr(item, 'updatedTime', '');
-          host.hostOfflineReason = getStringAttr(item, 'hostOfflineReason', '');
+          host.hostName = base.getStringAttr(item, 'hostName', '');
+          host.hostId = base.getStringAttr(item, 'hostId', '');
+          host.status = base.getStringAttr(item, 'status', '');
+          host.jabberId = base.getStringAttr(item, 'jabberId', '');
+          host.publicKey = base.getStringAttr(item, 'publicKey', '');
+          host.hostVersion = base.getStringAttr(item, 'hostVersion', '');
+          host.tokenUrlPatterns =
+              base.getArrayAttr(item, 'tokenUrlPatterns', []);
+          host.updatedTime = base.getStringAttr(item, 'updatedTime', '');
+          host.hostOfflineReason =
+              base.getStringAttr(item, 'hostOfflineReason', '');
           return host;
       });
       onDone(hosts);

remoting/webapp/crd/js/it2me_host_facade.js

@@ -208,11 +208,11 @@ remoting.It2MeHostFacade.prototype.getClient = function() {
  */
 remoting.It2MeHostFacade.prototype.onIncomingMessage_ =
     function(message) {
-  var type = getStringAttr(message, 'type');
+  var type = base.getStringAttr(message, 'type');
 
   switch (type) {
     case 'helloResponse':
-      var version = getStringAttr(message, 'version');
+      var version = base.getStringAttr(message, 'version');
       console.log('Host version: ', version);
       this.initialized_ = true;
       // A "hello" request is sent immediately after the native messaging host
@@ -236,19 +236,20 @@ remoting.It2MeHostFacade.prototype.onIncomingMessage_ =
       break;
 
     case 'hostStateChanged':
-      var stateString = getStringAttr(message, 'state');
+      var stateString = base.getStringAttr(message, 'state');
       console.log('hostStateChanged received: ', stateString);
       var state = remoting.HostSession.State.fromString(stateString);
 
       switch (state) {
         case remoting.HostSession.State.RECEIVED_ACCESS_CODE:
-          var accessCode = getStringAttr(message, 'accessCode');
-          var accessCodeLifetime = getNumberAttr(message, 'accessCodeLifetime');
+          var accessCode = base.getStringAttr(message, 'accessCode');
+          var accessCodeLifetime =
+              base.getNumberAttr(message, 'accessCodeLifetime');
           this.onReceivedAccessCode_(accessCode, accessCodeLifetime);
           break;
 
         case remoting.HostSession.State.CONNECTED:
-          var client = getStringAttr(message, 'client');
+          var client = base.getStringAttr(message, 'client');
           this.onConnected_(client);
           break;
       }
@@ -260,13 +261,13 @@ remoting.It2MeHostFacade.prototype.onIncomingMessage_ =
     case 'natPolicyChanged':
       if (this.onNatPolicyChanged_) {
         var natTraversalEnabled =
-            getBooleanAttr(message, 'natTraversalEnabled');
+            base.getBooleanAttr(message, 'natTraversalEnabled');
         this.onNatPolicyChanged_(natTraversalEnabled);
       }
       break;
 
     case 'error':
-      console.error(getStringAttr(message, 'description'));
+      console.error(base.getStringAttr(message, 'description'));
       if (this.onError_) {
         this.onError_(remoting.Error.unexpected());
       }

remoting/webapp/crd/js/typecheck.js

@@ -2,6 +2,148 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+
+/** @suppress {duplicate} */
+var remoting = remoting || {};
+
+(function() {
+'use strict';
+
+/**
+ * @param {*} value
+ * @return {boolean}
+ */
+var isArray = function(value) {
+  return Array.isArray(value);
+};
+
+/**
+ * @param {*} value
+ * @return {boolean}
+ */
+var isBoolean = function(value) {
+  return typeof value == 'boolean';
+};
+
+/**
+ * @param {*} value
+ * @return {boolean}
+ */
+var isNumber = function(value) {
+  return typeof value == 'number';
+};
+
+/**
+ * @param {*} value
+ * @return {boolean}
+ */
+var isObject = function(value) {
+  return value != null && typeof value == 'object' && !Array.isArray(value);
+};
+
+/**
+ * @param {*} value
+ * @return {boolean}
+ */
+var isString = function(value) {
+  return typeof value == 'string';
+};
+
+/**
+ * @param {*} value
+ * @return {string}
+ */
+var jsonTypeOf = function(value) {
+  if (typeof value == 'object') {
+    if (value === null) {
+      return 'null';
+    } else if (Array.isArray(value)) {
+      return 'array';
+    } else {
+      return 'object';
+    }
+  } else {
+    return typeof value;
+  }
+};
+
+/**
+ * @param {*} value the value to check; must be an object
+ * @param {function(*):boolean} pred
+ * @param {string} typeDesc
+ * @return {*} the argument
+ */
+var assertType = function(value, pred, typeDesc) {
+  if (pred(value)) {
+    return value;
+  } else {
+    throw new Error('Invalid data type' +
+                    ' (expected: ' + typeDesc +
+                    ', actual: ' + jsonTypeOf(value) + ')');
+  }
+};
+
+/**
+ * @param {*} value the value to check; must be an object
+ * @return {!Array} the argument
+ */
+base.assertArray = function(value) {
+  return /** @type {!Array} */ (assertType(value, isArray, 'array'));
+};
+
+/**
+ * @param {*} value the value to check; must be a boolean
+ * @return {boolean} the argument
+ */
+base.assertBoolean = function(value) {
+  return /** @type {boolean} */ (assertType(value, isBoolean, 'boolean'));
+};
+
+/**
+ * @param {*} value the value to check; must be a number
+ * @return {number} the argument
+ */
+base.assertNumber = function(value) {
+  return /** @type {number} */ (assertType(value, isNumber, 'number'));
+};
+
+/**
+ * @param {*} value the value to check; must be an object
+ * @return {!Object} the argument
+ */
+base.assertObject = function(value) {
+  return /** @type {!Object} */ (assertType(value, isObject, 'object'));
+};
+
+/**
+ * @param {*} value the value to check; must be a string
+ * @return {string} the argument
+ */
+base.assertString = function(value) {
+  return /** @type {string} */ (assertType(value, isString, 'string'));
+};
+
+/**
+ * @param {Object<string,*>} dict The dictionary containing the |key|
+ * @param {string} key The key to typecheck in the |dict|.
+ * @param {function(*):boolean} pred
+ * @param {string} typeDesc
+ * @param {*=} opt_default The value to return if pred returns false.
+ * @return {*} The |key| attribute value.
+ */
+var getTypedAttr = function(dict, key, pred, typeDesc, opt_default) {
+  var value = /** @type {*} */ (dict[key]);
+  if (pred(value)) {
+    return value;
+  } else if (opt_default !== undefined) {
+    return opt_default;
+  } else {
+    throw new Error('Invalid data type for ' + key +
+                    ' (expected: ' + typeDesc + ', actual: ' +
+                    jsonTypeOf(value) + ')');
+  }
+};
+
 /**
  * Get the |key| attribute in the given |dict| and verify that it is an
  * array value.
@@ -14,18 +156,10 @@
  * @param {Array=} opt_default The value to return if the key is not a bool.
  * @return {Array} The |key| attribute value as an object.
  */
-function getArrayAttr(dict, key, opt_default) {
-  var value = /** @type {Array} */ (dict[key]);
-  if (!(value instanceof Array)) {
-    if (opt_default === undefined) {
-      throw 'Invalid data type for ' + key +
-          ' (expected: array, actual: ' + typeof value + ')';
-    } else {
-      return opt_default;
-    }
-  }
-  return value;
-}
+base.getArrayAttr = function(dict, key, opt_default) {
+  return /** @type {Array} */ (
+      getTypedAttr(dict, key, isArray, 'array', opt_default));
+};
 
 /**
  * Get the |key| attribute in the given |dict| and verify that it is a
@@ -39,21 +173,14 @@ function getArrayAttr(dict, key, opt_default) {
  * @param {boolean=} opt_default The value to return if the key is not a bool.
  * @return {boolean} The |key| attribute value as a boolean.
  */
-function getBooleanAttr(dict, key, opt_default) {
-  var value = /** @type {boolean} */ (dict[key]);
+base.getBooleanAttr = function(dict, key, opt_default) {
+  var value = /** @type {*} */ (dict[key]);
   if (value == 'true' || value == 'false') {
-    return (value == 'true');
-  }
-  if (typeof value !== 'boolean') {
-    if (opt_default === undefined) {
-      throw 'Invalid data type for ' + key +
-          ' (expected: boolean, actual: ' + typeof value + ')';
-    } else {
-      return opt_default;
-    }
+    return value == 'true';
   }
-  return value;
-}
+  return /** @type {boolean} */ (
+      getTypedAttr(dict, key, isBoolean, 'boolean', opt_default));
+};
 
 /**
  * Get the |key| attribute in the given |dict| and verify that it is a
@@ -67,18 +194,10 @@ function getBooleanAttr(dict, key, opt_default) {
  * @param {number=} opt_default The value to return if the key is not a number.
  * @return {number} The |key| attribute value as a number.
  */
-function getNumberAttr(dict, key, opt_default) {
-  var value = /** @type {number} */(dict[key]);
-  if (typeof value != 'number') {
-    if (opt_default === undefined) {
-      throw 'Invalid data type for ' + key +
-          ' (expected: number, actual: ' + typeof value + ')';
-    } else {
-      return opt_default;
-    }
-  }
-  return value;
-}
+base.getNumberAttr = function(dict, key, opt_default) {
+  return /** @type {number} */ (
+      getTypedAttr(dict, key, isNumber, 'number', opt_default));
+};
 
 /**
  * Get the |key| attribute in the given |dict| and verify that it is an
@@ -90,20 +209,12 @@ function getNumberAttr(dict, key, opt_default) {
  * @param {Object<string,*>} dict The dictionary containing the |key|
  * @param {string} key The key to typecheck in the |dict|.
  * @param {Object=} opt_default The value to return if the key is not a bool.
- * @return {Object} The |key| attribute value as an object.
- */
-function getObjectAttr(dict, key, opt_default) {
-  var value = /** @type {Object} */ (dict[key]);
-  if (typeof value != 'object') {
-    if (opt_default === undefined) {
-      throw 'Invalid data type for ' + key +
-          ' (expected: object, actual: ' + typeof value + ')';
-    } else {
-      return opt_default;
-    }
-  }
-  return value;
-}
+ * @return {!Object} The |key| attribute value as an object.
+ */
+base.getObjectAttr = function(dict, key, opt_default) {
+  return /** @type {!Object} */ (
+      getTypedAttr(dict, key, isObject, 'object', opt_default));
+};
 
 /**
  * Get the |key| attribute in the given |dict| and verify that it is a
@@ -117,18 +228,10 @@ function getObjectAttr(dict, key, opt_default) {
  * @param {string=} opt_default The value to return if the key is not a string.
  * @return {string} The |key| attribute value as a string.
  */
-function getStringAttr(dict, key, opt_default) {
-  var value =  /** @type {string} */ (dict[key]);
-  if (typeof value != 'string') {
-    if (opt_default === undefined) {
-      throw 'Invalid data type for ' + key +
-          ' (expected: string, actual: ' + typeof value + ')';
-    } else {
-      return opt_default;
-    }
-  }
-  return value;
-}
+base.getStringAttr = function(dict, key, opt_default) {
+  return /** @type {string} */ (
+      getTypedAttr(dict, key, isString, 'string', opt_default));
+};
 
 /**
  * Return a JSON object parsed from a string.
@@ -139,10 +242,8 @@ function getStringAttr(dict, key, opt_default) {
  * @param {string} jsonString The JSON string to parse.
  * @return {Object} The JSON object created from the |jsonString|.
  */
-function getJsonObjectFromString(jsonString) {
-  var value = base.jsonParseSafe(jsonString);
-  if (typeof value != 'object') {
-    throw 'Invalid data type (expected: Object, actual: ' + typeof value + ')';
-  }
-  return value;
+base.getJsonObjectFromString = function(jsonString) {
+  return base.assertObject(base.jsonParseSafe(jsonString));
+};
+
+})();
\ No newline at end of file
-}

remoting/webapp/crd/js/video_frame_recorder.js

@@ -63,8 +63,8 @@ remoting.VideoFrameRecorder.prototype.handleMessage =
     return false;
   }
 
-  var messageType = getStringAttr(message, 'type');
-  var messageData = getStringAttr(message, 'data');
+  var messageType = base.getStringAttr(message, 'type');
+  var messageData = base.getStringAttr(message, 'data');
 
   if (messageType == 'next-frame-reply') {
     if (!this.fileWriter_) {

remoting/webapp/js_proto/qunit_proto.js

@@ -68,6 +68,20 @@ QUnit.Assert.prototype.equal = function(a, b, opt_message) {};
  */
 QUnit.Assert.prototype.expect = function(assertionCount) {};
 
+/**
+ * @param {*} a
+ * @param {*} b
+ * @param {string=} opt_message
+ */
+QUnit.Assert.prototype.strictEqual = function(a, b, opt_message) {};
+
+/**
+ * @param {function()} a
+ * @param {*=} opt_b
+ * @param {string=} opt_message
+ */
+QUnit.Assert.prototype.throws = function(a, opt_b, opt_message) {};
+
 /**
  * @typedef {{
  *   beforeEach: (function(QUnit.Assert=) | undefined),