Move prompt, confirm and sendcastapi to one module each

src/components/castSenderApi.js

@@ -0,0 +1,34 @@
+define([], function() {
+    'use strict';
+
+    if (window.appMode === "cordova" || window.appMode === "android") {
+        return {
+            load: function () {
+                window.chrome = window.chrome || {};
+                return Promise.resolve();
+            }
+        };
+    } else {
+        var ccLoaded = false;
+        return {
+            load: function () {
+                if (ccLoaded) {
+                    return Promise.resolve();
+                }
+
+                return new Promise(function (resolve, reject) {
+                    var fileref = document.createElement("script");
+                    fileref.setAttribute("type", "text/javascript");
+
+                    fileref.onload = function () {
+                        ccLoaded = true;
+                        resolve();
+                    };
+
+                    fileref.setAttribute("src", "https://www.gstatic.com/cv/js/sender/v1/cast_sender.js");
+                    document.querySelector("head").appendChild(fileref);
+                });
+            }
+        };
+    }
+});