Added more typechecking functions and unit tests for existing code.

remoting/webapp/crd/js/client_plugin_host_desktop_impl.js

Index: remoting/webapp/crd/js/client_plugin_host_desktop_impl.js
diff --git a/remoting/webapp/crd/js/client_plugin_host_desktop_impl.js b/remoting/webapp/crd/js/client_plugin_host_desktop_impl.js
index 78ca6df168a33d4830d099d78835f5c59588bac9..71cb164a0c1f265acd6f97ddb71ae61852693b18 100644
--- a/remoting/webapp/crd/js/client_plugin_host_desktop_impl.js
+++ b/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) {