Reverts third_party/protobuf: Update to HEAD (f52e188fe4)

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

Index: third_party/protobuf/python/google/protobuf/pyext/extension_dict.h
diff --git a/third_party/protobuf/python/google/protobuf/pyext/extension_dict.h b/third_party/protobuf/python/google/protobuf/pyext/extension_dict.h
index 65b878625a3cd04e28943a853df7b00e163dc0f5..2456eda1e61c56aa471d51943059587691e21bc3 100644
--- a/third_party/protobuf/python/google/protobuf/pyext/extension_dict.h
+++ b/third_party/protobuf/python/google/protobuf/pyext/extension_dict.h
@@ -86,6 +86,49 @@ namespace extension_dict {
 // Builds an Extensions dict for a specific message.
 ExtensionDict* NewExtensionDict(CMessage *parent);
 
+// Gets the number of extension values in this ExtensionDict as a python object.
+//
+// Returns a new reference.
+PyObject* len(ExtensionDict* self);
+
+// Releases extensions referenced outside this dictionary to keep outside
+// references alive.
+//
+// Returns 0 on success, -1 on failure.
+int ReleaseExtension(ExtensionDict* self,
+                     PyObject* extension,
+                     const FieldDescriptor* descriptor);
+
+// Gets an extension from the dict for the given extension descriptor.
+//
+// Returns a new reference.
+PyObject* subscript(ExtensionDict* self, PyObject* key);
+
+// Assigns a value to an extension in the dict. Can only be used for singular
+// simple types.
+//
+// Returns 0 on success, -1 on failure.
+int ass_subscript(ExtensionDict* self, PyObject* key, PyObject* value);
+
+// Clears an extension from the dict. Will release the extension if there
+// is still an external reference left to it.
+//
+// Returns None on success.
+PyObject* ClearExtension(ExtensionDict* self,
+                                       PyObject* extension);
+
+// Gets an extension from the dict given the extension name as opposed to
+// descriptor.
+//
+// Returns a new reference.
+PyObject* _FindExtensionByName(ExtensionDict* self, PyObject* name);
+
+// Gets an extension from the dict given the extension field number as
+// opposed to descriptor.
+//
+// Returns a new reference.
+PyObject* _FindExtensionByNumber(ExtensionDict* self, PyObject* number);
+
 }  // namespace extension_dict
 }  // namespace python
 }  // namespace protobuf