Mojom: Add 'default' keyword for initializing structs to non-null value.

mojo/public/cpp/bindings/tests/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/interfaces/bindings/tests/sample_service.mojom.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ skipping 341 matching lines @@
   EXPECT_EQ(1234, defaults->a10);
   EXPECT_TRUE(defaults->a11);
   EXPECT_FALSE(defaults->a12);
   EXPECT_FLOAT_EQ(123.25f, defaults->a13);
   EXPECT_DOUBLE_EQ(1234567890.123, defaults->a14);
   EXPECT_DOUBLE_EQ(1E10, defaults->a15);
   EXPECT_DOUBLE_EQ(-1.2E+20, defaults->a16);
   EXPECT_DOUBLE_EQ(1.23E-20, defaults->a17);
   EXPECT_TRUE(defaults->a18.is_null());
   EXPECT_TRUE(defaults->a19.is_null());
-  // TODO(mpcomplete): Test defaults.Point and defaults.Thing once we can
-  // initialize them to "default".
   EXPECT_EQ(Bar::TYPE_BOTH, defaults->a20);
+  EXPECT_TRUE(defaults->a21.is_null());
+  ASSERT_FALSE(defaults->a22.is_null());
+  EXPECT_EQ(imported::SHAPE_RECTANGLE, defaults->a22->shape);
+  EXPECT_EQ(imported::COLOR_BLACK, defaults->a22->color);
 }
 
 }  // namespace
 }  // namespace sample