Mojo cpp bindings: support Clone() for structs and arrays which don't contain handles.

mojo/public/cpp/bindings/tests/struct_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 "mojo/public/cpp/bindings/lib/fixed_buffer.h"
 #include "mojo/public/cpp/environment/environment.h"
 #include "mojo/public/interfaces/bindings/tests/test_structs.mojom.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace mojo {
@@ skipping 33 matching lines @@
   EXPECT_FALSE(rect);
 
   rect = MakeRect();
   EXPECT_FALSE(rect.is_null());
   EXPECT_FALSE(!rect);
   EXPECT_TRUE(rect);
 
   CheckRect(*rect);
 }
 
+TEST_F(StructTest, Clone) {
+  NamedRegionPtr region;
+
+  NamedRegionPtr clone_region = region.Clone();
+  EXPECT_TRUE(clone_region.is_null());
+
+  region = NamedRegion::New();
+  clone_region = region.Clone();
+  EXPECT_TRUE(clone_region->name.is_null());
+  EXPECT_TRUE(clone_region->rects.is_null());
+
+  region->name = "hello world";
+  clone_region = region.Clone();
+  EXPECT_EQ(region->name, clone_region->name);
+
+  region->rects = Array<RectPtr>(2);
+  region->rects[1] = MakeRect();
+  clone_region = region.Clone();
+  EXPECT_EQ(2u, clone_region->rects.size());
+  EXPECT_TRUE(clone_region->rects[0].is_null());
+  CheckRect(*clone_region->rects[1]);
+
+  // NoDefaultFieldValues contains handles, so Clone() is not available, but
+  // NoDefaultFieldValuesPtr should still compile.
+  NoDefaultFieldValuesPtr no_default_field_values(NoDefaultFieldValues::New());
+  EXPECT_FALSE(no_default_field_values->f13.is_valid());
+}
+
 // Serialization test of a struct with no pointer or handle members.
 TEST_F(StructTest, Serialization_Basic) {
   RectPtr rect(MakeRect());
 
   size_t size = GetSerializedSize_(rect);
   EXPECT_EQ(8U + 16U, size);
 
   mojo::internal::FixedBuffer buf(size);
   internal::Rect_Data* data;
   Serialize_(rect.Pass(), &buf, &data);
@@ skipping 76 matching lines @@
 
   NamedRegionPtr region2;
   Deserialize_(data, &region2);
 
   EXPECT_TRUE(region2->name.is_null());
   EXPECT_TRUE(region2->rects.is_null());
 }
 
 }  // namespace test
 }  // namespace mojo