chromeos: Make dbus::MessageReader memory ownership explicit

dbus/message.h

 // Copyright (c) 2012 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.
 
 #ifndef DBUS_MESSAGE_H_
 #define DBUS_MESSAGE_H_
 
 #include <string>
 #include <vector>
 #include <dbus/dbus.h>
@@ skipping 390 matching lines @@
   bool PopStruct(MessageReader* sub_reader);
   bool PopDictEntry(MessageReader* sub_reader);
   bool PopVariant(MessageReader* sub_reader);
 
   // Gets the array of bytes at the current iterator position.
   // Returns true and advances the iterator on success.
   //
   // Arrays of bytes are often used for exchanging binary blobs hence it's
   // worth having a specialized function.
   //
-  // |bytes| must be copied if the contents will be referenced after the
-  // MessageReader is destroyed.
-  bool PopArrayOfBytes(uint8** bytes, size_t* length);
+  // Ownership of the memory pointed to by |bytes| remains with the
+  // MessageReader; |bytes| must be copied if the contents will be referenced
+  // after the MessageReader is destroyed.
+  bool PopArrayOfBytes(const uint8** bytes, size_t* length);
 
-  // Gets the array of strings at the current iterator position.
-  // Returns true and advances the iterator on success.
+  // Gets the array of strings at the current iterator position. |strings| is
+  // cleared before being modified. Returns true and advances the iterator on
+  // success.
   //
   // Arrays of strings are often used to communicate with D-Bus
   // services like KWallet, hence it's worth having a specialized
   // function.
   bool PopArrayOfStrings(std::vector<std::string>* strings);
 
   // Gets the array of object paths at the current iterator position.
-  // Returns true and advances the iterator on success.
+  // |object_paths| is cleared before being modified. Returns true and advances
+  // the iterator on success.
   //
   // Arrays of object paths are often used to communicate with D-Bus
   // services like NetworkManager, hence it's worth having a specialized
   // function.
   bool PopArrayOfObjectPaths(std::vector<ObjectPath>* object_paths);
 
   // Gets the array of bytes at the current iterator position. It then parses
   // this binary blob into the protocol buffer supplied.
   // Returns true and advances the iterator on success. On failure returns false
   // and emits an error message on the source of the failure. The two most
@@ skipping 41 matching lines @@
 
   Message* message_;
   DBusMessageIter raw_message_iter_;
 
   DISALLOW_COPY_AND_ASSIGN(MessageReader);
 };
 
 }  // namespace dbus
 
 #endif  // DBUS_MESSAGE_H_