ipc: Wrap unit test into IPC namespace.

ipc/ipc_message_utils_unittest.cc

 // 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.
 
+#include "ipc/ipc_message_utils.h"
+
 #include "base/file_path.h"
 #include "ipc/ipc_message.h"
-#include "ipc/ipc_message_utils.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
-using namespace IPC;
-
+namespace IPC {
 namespace {
 
 // Tests nesting of messages as parameters to other messages.
 TEST(IPCMessageUtilsTest, NestedMessages) {
   int32 nested_routing = 12;
   uint32 nested_type = 78;
   int nested_content = 456789;
   Message::PriorityValue nested_priority = Message::PRIORITY_HIGH;
   Message nested_msg(nested_routing, nested_type, nested_priority);
   nested_msg.set_sync();
@@ skipping 42 matching lines @@
   ParamTraits<base::FilePath::StringType>::Write(&message, bad_string);
 
   PickleIterator iter(message);
   base::FilePath ok_path;
   base::FilePath bad_path;
   ASSERT_TRUE(ParamTraits<base::FilePath>::Read(&message, &iter, &ok_path));
   ASSERT_FALSE(ParamTraits<base::FilePath>::Read(&message, &iter, &bad_path));
 }
 
 }  // namespace
+}  // namespace IPC