Update third_party/protobuf to protobuf-v3.0.0-beta-3

third_party/protobuf/python/google/protobuf/pyext/repeated_composite_container.h

Index: third_party/protobuf/python/google/protobuf/pyext/repeated_composite_container.h
diff --git a/third_party/protobuf/python/google/protobuf/pyext/repeated_composite_container.h b/third_party/protobuf/python/google/protobuf/pyext/repeated_composite_container.h
index 58d37b020734950fe26d4da91f75403034467f63..a7b56b61b363d36eb652ab7fd795e4fc07efae0b 100644
--- a/third_party/protobuf/python/google/protobuf/pyext/repeated_composite_container.h
+++ b/third_party/protobuf/python/google/protobuf/pyext/repeated_composite_container.h
@@ -58,6 +58,7 @@ using internal::shared_ptr;
 namespace python {
 
 struct CMessage;
+struct CMessageClass;
 
 // A RepeatedCompositeContainer can be in one of two states: attached
 // or released.
@@ -94,8 +95,8 @@ typedef struct RepeatedCompositeContainer {
   // calling Clear() or ClearField() on the parent.
   Message* message;
 
-  // A callable that is used to create new child messages.
-  PyObject* subclass_init;
+  // The type used to create new child messages.
+  CMessageClass* child_message_class;
 
   // A list of child messages.
   PyObject* child_messages;
@@ -110,7 +111,7 @@ namespace repeated_composite_container {
 PyObject *NewContainer(
     CMessage* parent,
     const FieldDescriptor* parent_field_descriptor,
-    PyObject *concrete_class);
+    CMessageClass *child_message_class);
 
 // Appends a new CMessage to the container and returns it.  The
 // CMessage is initialized using the content of kwargs.