Add support for dumping code in jitdump file format

runtime/vm/code_observers.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+
 #include "vm/code_observers.h"
 
+#include "platform/thread.h"
 #include "vm/os.h"
 
 namespace dart {
 
+Mutex* CodeObservers::mutex_ = NULL;
 intptr_t CodeObservers::observers_length_ = 0;
 CodeObserver** CodeObservers::observers_ = NULL;
 
 
 void CodeObservers::Register(CodeObserver* observer) {
   observers_length_++;
   observers_ = reinterpret_cast<CodeObserver**>(
       realloc(observers_, sizeof(observer) * observers_length_));
   if (observers_ == NULL) {
     FATAL("failed to grow code observers array");
@@ skipping 28 matching lines @@
   for (intptr_t i = 0; i < observers_length_; i++) {
     delete observers_[i];
   }
   free(observers_);
   observers_length_ = 0;
   observers_ = NULL;
 }
 
 
 void CodeObservers::InitOnce() {
+  ASSERT(mutex_ == NULL);
+  mutex_ = new Mutex();
+  ASSERT(mutex_ != NULL);
   OS::RegisterCodeObservers();
 }
 
 
 }  // namespace dart