Support COM in SequencedWorkerPool. This will be used by some code that

base/threading/sequenced_worker_pool.cc

Index: base/threading/sequenced_worker_pool.cc
===================================================================
--- base/threading/sequenced_worker_pool.cc	(revision 264688)
+++ base/threading/sequenced_worker_pool.cc	(working copy)
@@ -32,6 +32,8 @@
 
 #if defined(OS_MACOSX)
 #include "base/mac/scoped_nsautorelease_pool.h"
+#elif defined(OS_WIN)
+#include "base/win/scoped_com_initializer.h"
 #endif
 
 #if !defined(OS_NACL)
@@ -491,6 +493,10 @@
 }
 
 void SequencedWorkerPool::Worker::Run() {
+#if defined(OS_WIN)
+  win::ScopedCOMInitializer com_initializer;
+#endif
+
   // Store a pointer to the running sequence in thread local storage for
   // static function access.
   g_lazy_tls_ptr.Get().Set(&running_sequence_);