Add CHECK on file descriptor in various IPC::ChannelHandle passed in.

content/ppapi_plugin/ppapi_thread.cc

 // Copyright (c) 2011 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 "content/ppapi_plugin/ppapi_thread.h"
 
 #include <limits>
 
 #include "base/command_line.h"
 #include "base/process_util.h"
@@ skipping 285 matching lines @@
     delete dispatcher;
     return false;
   }
 
   handle->name = plugin_handle.name;
 #if defined(OS_POSIX)
   // On POSIX, transfer ownership of the renderer-side (client) FD.
   // This ensures this process will be notified when it is closed even if a
   // connection is not established.
   handle->socket = base::FileDescriptor(dispatcher->TakeRendererFD(), true);
+  // Check the validity of fd for bug investigation. Remove after fixed.
+  // See for details: crbug.com/103957.
+  CHECK_NE(-1, handle->socket.fd);
   if (handle->socket.fd == -1)
     return false;
 #endif
 
   // From here, the dispatcher will manage its own lifetime according to the
   // lifetime of the attached channel.
   return true;
 }