Revert https://codereview.chromium.org/1291903002 (protobuf roll).

third_party/protobuf/python/google/protobuf/pyext/python_protobuf.cc

Index: third_party/protobuf/python/google/protobuf/pyext/python_protobuf.cc
diff --git a/third_party/protobuf/src/google/protobuf/arenastring.cc b/third_party/protobuf/python/google/protobuf/pyext/python_protobuf.cc
similarity index 65%
rename from third_party/protobuf/src/google/protobuf/arenastring.cc
rename to third_party/protobuf/python/google/protobuf/pyext/python_protobuf.cc
index cce61d74de241401917ef30c8a5a707fed10e177..1b1ab5d1dc7f4bf986884718c67d69a460232ada 100644
--- a/third_party/protobuf/src/google/protobuf/arenastring.cc
+++ b/third_party/protobuf/python/google/protobuf/pyext/python_protobuf.cc
@@ -1,6 +1,6 @@
 // Protocol Buffers - Google's data interchange format
 // Copyright 2008 Google Inc.  All rights reserved.
-// https://developers.google.com/protocol-buffers/
+// http://code.google.com/p/protobuf/
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
@@ -28,26 +28,36 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// The ArenaString implementation is not included in the open-source release. Do
-// not include this file in the distribution.
+// Author: qrczak@google.com (Marcin Kowalczyk)
 
-#include <google/protobuf/arenastring.h>
+#include <google/protobuf/pyext/python_protobuf.h>
 
 namespace google {
 namespace protobuf {
-namespace internal {
+namespace python {
 
+static const Message* GetCProtoInsidePyProtoStub(PyObject* msg) {
+  return NULL;
+}
+static Message* MutableCProtoInsidePyProtoStub(PyObject* msg) {
+  return NULL;
+}
 
-void ArenaStringPtr::AssignWithDefault(const ::std::string* default_value,
-                                       ArenaStringPtr value) {
-  const ::std::string* me = *UnsafeRawStringPointer();
-  const ::std::string* other = *value.UnsafeRawStringPointer();
-  // If the pointers are the same then do nothing.
-  if (me != other) {
-    SetNoArena(default_value, value.GetNoArena(default_value));
-  }
+// This is initialized with a default, stub implementation.
+// If python-google.protobuf.cc is loaded, the function pointer is overridden
+// with a full implementation.
+const Message* (*GetCProtoInsidePyProtoPtr)(PyObject* msg) =
+    GetCProtoInsidePyProtoStub;
+Message* (*MutableCProtoInsidePyProtoPtr)(PyObject* msg) =
+    MutableCProtoInsidePyProtoStub;
+
+const Message* GetCProtoInsidePyProto(PyObject* msg) {
+  return GetCProtoInsidePyProtoPtr(msg);
+}
+Message* MutableCProtoInsidePyProto(PyObject* msg) {
+  return MutableCProtoInsidePyProtoPtr(msg);
 }
 
-}  // namespace internal
+}  // namespace python
 }  // namespace protobuf
 }  // namespace google