Add validation logic for non-nullable types.

mojo/public/cpp/bindings/lib/validation_errors.cc

Index: mojo/public/cpp/bindings/lib/validation_errors.cc
diff --git a/mojo/public/cpp/bindings/lib/validation_errors.cc b/mojo/public/cpp/bindings/lib/validation_errors.cc
index c1bd9ae76421ca158c3397781b1c9c6599b6b508..37cd7d2062bc85f8957c60a4b93700cfb4d6bd15 100644
--- a/mojo/public/cpp/bindings/lib/validation_errors.cc
+++ b/mojo/public/cpp/bindings/lib/validation_errors.cc
@@ -28,8 +28,12 @@ const char* ValidationErrorToString(ValidationError error) {
       return "VALIDATION_ERROR_UNEXPECTED_ARRAY_HEADER";
     case VALIDATION_ERROR_ILLEGAL_HANDLE:
       return "VALIDATION_ERROR_ILLEGAL_HANDLE";
+    case VALIDATION_ERROR_UNEXPECTED_INVALID_HANDLE:
+      return "VALIDATION_ERROR_UNEXPECTED_INVALID_HANDLE";
     case VALIDATION_ERROR_ILLEGAL_POINTER:
       return "VALIDATION_ERROR_ILLEGAL_POINTER";
+    case VALIDATION_ERROR_UNEXPECTED_NULL_POINTER:
+      return "VALIDATION_ERROR_UNEXPECTED_NULL_POINTER";
     case VALIDATION_ERROR_MESSAGE_HEADER_INVALID_FLAG_COMBINATION:
       return "VALIDATION_ERROR_MESSAGE_HEADER_INVALID_FLAG_COMBINATION";
     case VALIDATION_ERROR_MESSAGE_HEADER_MISSING_REQUEST_ID:
@@ -50,6 +54,8 @@ ValidationErrorObserverForTesting::ValidationErrorObserverForTesting()
     : last_error_(VALIDATION_ERROR_NONE) {
   MOJO_DCHECK(!g_validation_error_observer);
   g_validation_error_observer = this;
+  MOJO_LOG(WARNING) << "Non-nullable validation is turned on for testing but "
+                    << "not for production code yet!";
 }
 
 ValidationErrorObserverForTesting::~ValidationErrorObserverForTesting() {
@@ -57,5 +63,9 @@ ValidationErrorObserverForTesting::~ValidationErrorObserverForTesting() {
   g_validation_error_observer = NULL;
 }
 
+bool IsNonNullableValidationEnabled() {
+  return !!g_validation_error_observer;
+}
+
 }  // namespace internal
 }  // namespace mojo