Support default values for POD struct fields in mojom IDL.

mojo/public/tests/bindings/sample_service_unittest.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <algorithm>
 #include <ostream>
 #include <string>
 
 #include "mojo/public/environment/environment.h"
 #include "mojom/sample_service.h"
@@ skipping 291 matching lines @@
 
   Foo foo = MakeFoo();
   CheckFoo(foo);
 
   mojo::ScopedMessagePipeHandle port0, port1;
   mojo::CreateMessagePipe(&port0, &port1);
 
   service->Frobinate(foo, Service::BAZ_EXTRA, port0.Pass());
 }
 
+TEST(BindingsSampleTest, DefaultValues) {
+  mojo::Environment env;
+  SimpleMessageReceiver receiver;
+  mojo::AllocationScope scope;
+
+  Bar bar = Bar::Builder().Finish();
+  EXPECT_EQ(255, bar.alpha());
+
+  Foo foo = Foo::Builder().Finish();
+  ASSERT_FALSE(foo.name().is_null());
+  EXPECT_EQ("Fooby", foo.name().To<std::string>());
+  EXPECT_TRUE(foo.a());
+}
+
 }  // namespace sample