Mojo C++ bindings: fix inlined union validation.

mojo/public/tools/bindings/generators/cpp_templates/union_definition.tmpl

Index: mojo/public/tools/bindings/generators/cpp_templates/union_definition.tmpl
diff --git a/mojo/public/tools/bindings/generators/cpp_templates/union_definition.tmpl b/mojo/public/tools/bindings/generators/cpp_templates/union_definition.tmpl
index f151a4e245cbb72298def31c840e05b6d9e05e44..af5ea9f8a8340512fdcd0784905ebf30b7077573 100644
--- a/mojo/public/tools/bindings/generators/cpp_templates/union_definition.tmpl
+++ b/mojo/public/tools/bindings/generators/cpp_templates/union_definition.tmpl
@@ -7,15 +7,27 @@ bool {{class_name}}::Validate(
     const void* data,
     mojo::internal::ValidationContext* validation_context,
     bool inlined) {
-  if (!data)
+  if (!data) {
+    DCHECK(!inlined);
     return true;
+  }
+
+  // If it is inlined, the alignment is already enforced by its enclosing
+  // object. We don't have to validate that.
+  DCHECK(!inlined || mojo::internal::IsAligned(data));
 
-  if (!ValidateUnionHeaderAndClaimMemory(data, inlined, validation_context))
+  if (!inlined &&
+      !mojo::internal::ValidateNonInlinedUnionHeaderAndClaimMemory(
+          data, validation_context)) {
     return false;
+  }
 
   const {{class_name}}* object = static_cast<const {{class_name}}*>(data);
   ALLOW_UNUSED_LOCAL(object);
 
+  if (inlined && object->is_null())
+    return true;
+
   switch (object->tag) {
 {%  for field in union.fields %}
     case {{enum_name}}::{{field.name|upper}}: {