Simplify implementation of Mutex.

src/debug.cc

Index: src/debug.cc
diff --git a/src/debug.cc b/src/debug.cc
index 04f8a7a0274eeaec9d401bc436aad178a182739f..a4f9197311dac5c30d2ea4d79b087f6415a41627 100644
--- a/src/debug.cc
+++ b/src/debug.cc
@@ -2605,7 +2605,6 @@ Debugger::Debugger(Isolate* isolate)
       message_handler_(NULL),
       debugger_unload_pending_(false),
       host_dispatch_handler_(NULL),
-      dispatch_handler_access_(OS::CreateMutex()),
       debug_message_dispatch_handler_(NULL),
       message_dispatch_helper_thread_(NULL),
       host_dispatch_micros_(100 * 1000),
@@ -2618,8 +2617,6 @@ Debugger::Debugger(Isolate* isolate)
 
 
 Debugger::~Debugger() {
-  delete dispatch_handler_access_;
-  dispatch_handler_access_ = 0;
   delete command_received_;
   command_received_ = 0;
 }
@@ -3302,7 +3299,7 @@ void Debugger::SetHostDispatchHandler(v8::Debug::HostDispatchHandler handler,
 
 void Debugger::SetDebugMessageDispatchHandler(
     v8::Debug::DebugMessageDispatchHandler handler, bool provide_locker) {
-  ScopedLock with(dispatch_handler_access_);
+  ScopedLock with(&dispatch_handler_access_);
   debug_message_dispatch_handler_ = handler;
 
   if (provide_locker && message_dispatch_helper_thread_ == NULL) {
@@ -3345,7 +3342,7 @@ void Debugger::ProcessCommand(Vector<const uint16_t> command,
 
   MessageDispatchHelperThread* dispatch_thread;
   {
-    ScopedLock with(dispatch_handler_access_);
+    ScopedLock with(&dispatch_handler_access_);
     dispatch_thread = message_dispatch_helper_thread_;
   }
 
@@ -3465,7 +3462,7 @@ void Debugger::WaitForAgent() {
 void Debugger::CallMessageDispatchHandler() {
   v8::Debug::DebugMessageDispatchHandler handler;
   {
-    ScopedLock with(dispatch_handler_access_);
+    ScopedLock with(&dispatch_handler_access_);
     handler = Debugger::debug_message_dispatch_handler_;
   }
   if (handler != NULL) {
@@ -3786,24 +3783,20 @@ void CommandMessageQueue::Expand() {
 
 
 LockingCommandMessageQueue::LockingCommandMessageQueue(Logger* logger, int size)
-    : logger_(logger), queue_(size) {
-  lock_ = OS::CreateMutex();
-}
+    : logger_(logger), queue_(size) {}
 
 
-LockingCommandMessageQueue::~LockingCommandMessageQueue() {
-  delete lock_;
-}
+LockingCommandMessageQueue::~LockingCommandMessageQueue() {}
 
 
-bool LockingCommandMessageQueue::IsEmpty() const {
-  ScopedLock sl(lock_);
+bool LockingCommandMessageQueue::IsEmpty() {
+  ScopedLock sl(&lock_);
   return queue_.IsEmpty();
 }
 
 
 CommandMessage LockingCommandMessageQueue::Get() {
-  ScopedLock sl(lock_);
+  ScopedLock sl(&lock_);
   CommandMessage result = queue_.Get();
   logger_->DebugEvent("Get", result.text());
   return result;
@@ -3811,14 +3804,14 @@ CommandMessage LockingCommandMessageQueue::Get() {
 
 
 void LockingCommandMessageQueue::Put(const CommandMessage& message) {
-  ScopedLock sl(lock_);
+  ScopedLock sl(&lock_);
   queue_.Put(message);
   logger_->DebugEvent("Put", message.text());
 }
 
 
 void LockingCommandMessageQueue::Clear() {
-  ScopedLock sl(lock_);
+  ScopedLock sl(&lock_);
   queue_.Clear();
 }
 
@@ -3826,19 +3819,17 @@ void LockingCommandMessageQueue::Clear() {
 MessageDispatchHelperThread::MessageDispatchHelperThread(Isolate* isolate)
     : Thread("v8:MsgDispHelpr"),
       isolate_(isolate), sem_(OS::CreateSemaphore(0)),
-      mutex_(OS::CreateMutex()), already_signalled_(false) {
-}
+      already_signalled_(false) {}
 
 
 MessageDispatchHelperThread::~MessageDispatchHelperThread() {
-  delete mutex_;
   delete sem_;
 }
 
 
 void MessageDispatchHelperThread::Schedule() {
   {
-    ScopedLock lock(mutex_);
+    ScopedLock lock(&mutex_);
     if (already_signalled_) {
       return;
     }
@@ -3852,7 +3843,7 @@ void MessageDispatchHelperThread::Run() {
   while (true) {
     sem_->Wait();
     {
-      ScopedLock lock(mutex_);
+      ScopedLock lock(&mutex_);
       already_signalled_ = false;
     }
     {