Fix leak in RemotePtr::operator=().

mojo/public/cpp/bindings/remote_ptr.h

 // Copyright 2013 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 MOJO_PUBLIC_CPP_BINDINGS_REMOTE_PTR_H_
 #define MOJO_PUBLIC_CPP_BINDINGS_REMOTE_PTR_H_
 
 #include <assert.h>
 
 #include "mojo/public/cpp/bindings/interface.h"
@@ skipping 68 matching lines @@
                      typename S::_Peer* peer,
                      ErrorHandler* error_handler = NULL,
                      MojoAsyncWaiter* waiter = GetDefaultAsyncWaiter())
       : state_(new State(ScopedMessagePipeHandle(interface_handle.Pass()), peer,
                          error_handler, waiter)) {
   }
 
   // Move-only constructor and operator=.
   RemotePtr(RValue other) : state_(other.object->release()) {}
   RemotePtr& operator=(RValue other) {
+    delete state_;
     state_ = other.object->release();
     return *this;
   }
 
   ~RemotePtr() {
     delete state_;
   }
 
   bool is_null() const {
     return !state_;
@@ skipping 48 matching lines @@
     state_ = NULL;
     return state;
   }
 
   State* state_;
 };
 
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_REMOTE_PTR_H_