Introduce InterfaceEndpointClient(IEC), InterfaceEndpointHandle and

mojo/public/js/tests/validation_unittest.js

Index: mojo/public/js/tests/validation_unittest.js
diff --git a/mojo/public/js/tests/validation_unittest.js b/mojo/public/js/tests/validation_unittest.js
index 2a70248e662ef561f0fa900b4ac51c3c6ab8f6c3..1866b8e7a65dd4b45cd2fd0ac0d93e18baf308f2 100644
--- a/mojo/public/js/tests/validation_unittest.js
+++ b/mojo/public/js/tests/validation_unittest.js
@@ -278,15 +278,10 @@ define([
     expect(testMessagePipe.result).toBe(core.RESULT_OK);
 
     endpoint.bind(testMessagePipe.handle1);
-    var testingController = endpoint.enableTestingMode();
-
-    var validationError;
-    testingController.setInvalidIncomingMessageHandler(function(error) {
-      validationError = error;
-    });
+    var observer = validator.ValidationErrorObserverForTesting.getInstance();
+    observer.reset();
 
     for (var i = 0; i < testFiles.length; i++) {
-      validationError = noError;
       var testMessage = readTestMessage(testFiles[i]);
       var handles = new Array(testMessage.handleCount);
 
@@ -297,8 +292,8 @@ define([
           core.WRITE_MESSAGE_FLAG_NONE);
       expect(writeMessageValue).toBe(core.RESULT_OK);
 
-      testingController.waitForNextMessage();
-      checkValidationResult(testFiles[i], validationError);
+      endpoint.waitForNextMessageForTesting();
+      checkValidationResult(testFiles[i], observer.lastError);
     }
 
     expect(core.close(testMessagePipe.handle0)).toBe(core.RESULT_OK);