We don't need a lock for the output queue on the main thread

src/optimizing-compiler-thread.cc

 // Copyright 2012 the V8 project 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 "src/optimizing-compiler-thread.h"
 
 #include "src/v8.h"
 
 #include "src/base/atomicops.h"
 #include "src/full-codegen.h"
@@ skipping 228 matching lines @@
     input_queue_semaphore_.Wait();
     // OSR jobs are dealt with separately.
     if (!job->info()->is_osr()) {
       DisposeOptimizedCompileJob(job, restore_function_code);
     }
   }
 }
 
 
 void OptimizingCompilerThread::FlushOutputQueue(bool restore_function_code) {
-  base::LockGuard<base::Mutex> access_output_queue_(&output_queue_mutex_);
   OptimizedCompileJob* job;
   while (output_queue_.Dequeue(&job)) {
     // OSR jobs are dealt with separately.
     if (!job->info()->is_osr()) {
       DisposeOptimizedCompileJob(job, restore_function_code);
     }
   }
 }
 
 
@@ skipping 241 matching lines @@
 
 
 bool OptimizingCompilerThread::IsOptimizerThread() {
   base::LockGuard<base::Mutex> lock_guard(&thread_id_mutex_);
   return ThreadId::Current().ToInteger() == thread_id_;
 }
 #endif
 
 
 } }  // namespace v8::internal