Make the new Mojo EDK work on XP.

mojo/edk/embedder/platform_channel_pair_win.cc

 // Copyright 2014 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 "mojo/edk/embedder/platform_channel_pair.h"
 
 #include <windows.h>
 
 #include <string>
 
@@ skipping 71 matching lines @@
       PlatformHandle(LongToHandle(client_handle_value)));
 }
 
 void PlatformChannelPair::PrepareToPassClientHandleToChildProcess(
     base::CommandLine* command_line,
     base::HandlesToInheritVector* handle_passing_info) const {
   DCHECK(command_line);
   DCHECK(handle_passing_info);
   DCHECK(client_handle_.is_valid());
 
-  CHECK_GE(base::win::GetVersion(), base::win::VERSION_VISTA);
-
-  handle_passing_info->push_back(client_handle_.get().handle);
+  if (base::win::GetVersion() >= base::win::VERSION_VISTA)
+    handle_passing_info->push_back(client_handle_.get().handle);
 
   // Log a warning if the command line already has the switch, but "clobber" it
   // anyway, since it's reasonably likely that all the switches were just copied
   // from the parent.
   LOG_IF(WARNING, command_line->HasSwitch(kMojoPlatformChannelHandleSwitch))
       << "Child command line already has switch --"
       << kMojoPlatformChannelHandleSwitch << "="
       << command_line->GetSwitchValueASCII(kMojoPlatformChannelHandleSwitch);
   // (Any existing switch won't actually be removed from the command line, but
   // the last one appended takes precedence.)
   command_line->AppendSwitchASCII(
       kMojoPlatformChannelHandleSwitch,
       base::IntToString(HandleToLong(client_handle_.get().handle)));
 }
 
 }  // namespace edk
 }  // namespace mojo