Fix windows build break.

runtime/vm/os_thread_win.cc

Index: runtime/vm/os_thread_win.cc
diff --git a/runtime/vm/os_thread_win.cc b/runtime/vm/os_thread_win.cc
index 3802a1633900b8e0df5205cc0eecff6e4a314f24..9d282bc2f8132d8046338fc320c7e9bba701b9a5 100644
--- a/runtime/vm/os_thread_win.cc
+++ b/runtime/vm/os_thread_win.cc
@@ -6,6 +6,7 @@
 #if defined(TARGET_OS_WINDOWS)
 
 #include "vm/growable_array.h"
+#include "vm/lockers.h"
 #include "vm/os_thread.h"
 
 #include <process.h>  // NOLINT
@@ -565,7 +566,7 @@ void ThreadLocalData::AddThreadLocal(ThreadLocalKey key,
     // We only care about thread locals with destructors.
     return;
   }
-  mutex_->Lock();
+  MutexLocker ml(mutex_, false);
 #if defined(DEBUG)
   // Verify that we aren't added twice.
   for (intptr_t i = 0; i < thread_locals_->length(); i++) {
@@ -575,12 +576,12 @@ void ThreadLocalData::AddThreadLocal(ThreadLocalKey key,
 #endif
   // Add to list.
   thread_locals_->Add(ThreadLocalEntry(key, destructor));
-  mutex_->Unlock();
 }
 
 
 void ThreadLocalData::RemoveThreadLocal(ThreadLocalKey key) {
-  ASSERT(thread_locals_ != NULL);  mutex_->Lock();
+  ASSERT(thread_locals_ != NULL);
+  MutexLocker ml(mutex_, false);
   intptr_t i = 0;
   for (; i < thread_locals_->length(); i++) {
     const ThreadLocalEntry& entry = thread_locals_->At(i);
@@ -590,11 +591,9 @@ void ThreadLocalData::RemoveThreadLocal(ThreadLocalKey key) {
   }
   if (i == thread_locals_->length()) {
     // Not found.
-    mutex_->Unlock();
     return;
   }
   thread_locals_->RemoveAt(i);
-  mutex_->Unlock();
 }
 
 
@@ -603,7 +602,7 @@ void ThreadLocalData::RemoveThreadLocal(ThreadLocalKey key) {
 void ThreadLocalData::RunDestructors() {
   ASSERT(thread_locals_ != NULL);
   ASSERT(mutex_ != NULL);
-  mutex_->Lock();
+  MutexLocker ml(mutex_, false);
   for (intptr_t i = 0; i < thread_locals_->length(); i++) {
     const ThreadLocalEntry& entry = thread_locals_->At(i);
     // We access the exiting thread's TLS variable here.
@@ -611,7 +610,6 @@ void ThreadLocalData::RunDestructors() {
     // We invoke the constructor here.
     entry.destructor()(p);
   }
-  mutex_->Unlock();
 }