Add OS::GetCurrentProcessId and prepend output from trace-gc with the current pid

src/platform-win32.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 609 matching lines @@
   int64_t offset = Time(time).DaylightSavingsOffset();
   return static_cast<double>(offset);
 }
 
 
 int OS::GetLastError() {
   return ::GetLastError();
 }
 
 
+int OS::GetCurrentProcessId() {
+  return static_cast<int>(::GetCurrentProcessId());
+}
+
+
 // ----------------------------------------------------------------------------
 // Win32 console output.
 //
 // If a Win32 application is linked as a console application it has a normal
 // standard output and standard error. In this case normal printf works fine
 // for output. However, if the application is linked as a GUI application,
 // the process doesn't have a console, and therefore (debugging) output is lost.
 // This is the case if we are embedded in a windows program (like a browser).
 // In order to be able to get debug output in this case the the debugging
 // facility using OutputDebugString. This output goes to the active debugger
@@ skipping 1477 matching lines @@
 
 
 void Sampler::Stop() {
   ASSERT(IsActive());
   SamplerThread::RemoveActiveSampler(this);
   SetActive(false);
 }
 
 
 } }  // namespace v8::internal