[AppRemoting] Break out AppRemoting shared module (re-land).

remoting/webapp/base/js/application.js

Index: remoting/webapp/base/js/application.js
diff --git a/remoting/webapp/base/js/application.js b/remoting/webapp/base/js/application.js
index 39104057951cbf622c49272612682077556ee662..ab3215bc4416e0be1042885cbb4fb56854f0215e 100644
--- a/remoting/webapp/base/js/application.js
+++ b/remoting/webapp/base/js/application.js
@@ -108,6 +108,11 @@ remoting.Application.prototype.getExtensionInfo = function() {
  */
 
 /** @return {string} */
+remoting.Application.prototype.getApplicationId = function() {
+  base.debug.assert(false, 'Subclass must override');
+};
+
+/** @return {string} */
 remoting.Application.prototype.getApplicationName = function() {
   base.debug.assert(false, 'Subclass must override');
 };
@@ -154,6 +159,11 @@ remoting.Application.prototype.exitApplication_ = function() {
 remoting.ApplicationInterface = function() {};
 
 /**
+ * @return {string} Application Id.
+ */
+remoting.ApplicationInterface.prototype.getApplicationId = function() {};
+
+/**
  * @return {string} Application product name to be used in UI.
  */
 remoting.ApplicationInterface.prototype.getApplicationName = function() {};