[vm] Move bin/lockers.h to platform/lockers.h

We have to place these classes into a platform namespace to avoid
conflicts with vm/lockers.h.

To avoid changes to files in bin we simply change bin/lockers.h
to introduce bin::{Monitor,Mutex}Locker aliases for
platform::{Monitor,Mutex}Locker.

TEST=ci
R=kustermann@google.com

Change-Id: I975f24a8499ea85d0ba887180a81287fcf4101bb
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/405460
Reviewed-by: Martin Kustermann <kustermann@google.com>
Commit-Queue: Slava Egorov <vegorov@google.com>

runtime/bin/eventhandler_win.h

@@ -16,6 +16,7 @@
 #include <utility>
 
 #include "bin/builtin.h"
+#include "bin/lockers.h"
 #include "bin/reference_counting.h"
 #include "bin/socket_base.h"
 #include "bin/thread.h"
@@ -29,7 +30,6 @@ class EventHandlerImplementation;
 class FileHandle;
 class Handle;
 class ListenSocket;
-class MonitorLocker;
 class SocketHandle;
 
 // An OverlappedBuffer encapsulates the OVERLAPPED structure and the

runtime/bin/lockers.h

@@ -5,49 +5,14 @@
 #ifndef RUNTIME_BIN_LOCKERS_H_
 #define RUNTIME_BIN_LOCKERS_H_
 
-#include "bin/thread.h"
 #include "platform/assert.h"
+#include "platform/lockers.h"
 
 namespace dart {
 namespace bin {
 
-class MutexLocker {
- public:
-  explicit MutexLocker(Mutex* mutex) : mutex_(mutex) {
-    ASSERT(mutex != nullptr);
-    mutex_->Lock();
-  }
-
-  virtual ~MutexLocker() { mutex_->Unlock(); }
-
- private:
-  Mutex* const mutex_;
-
-  DISALLOW_COPY_AND_ASSIGN(MutexLocker);
-};
-
-class MonitorLocker {
- public:
-  explicit MonitorLocker(Monitor* monitor) : monitor_(monitor) {
-    ASSERT(monitor != nullptr);
-    monitor_->Enter();
-  }
-
-  virtual ~MonitorLocker() { monitor_->Exit(); }
-
-  Monitor::WaitResult Wait(int64_t millis = Monitor::kNoTimeout) {
-    return monitor_->Wait(millis);
-  }
-
-  void Notify() { monitor_->Notify(); }
-
-  void NotifyAll() { monitor_->NotifyAll(); }
-
- private:
-  Monitor* const monitor_;
-
-  DISALLOW_COPY_AND_ASSIGN(MonitorLocker);
-};
+using MutexLocker = dart::platform::MutexLocker;
+using MonitorLocker = dart::platform::MonitorLocker;
 
 }  // namespace bin
 }  // namespace dart

runtime/platform/lockers.h

@@ -0,0 +1,55 @@
+// Copyright (c) 2025, 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.
+
+#ifndef RUNTIME_PLATFORM_LOCKERS_H_
+#define RUNTIME_PLATFORM_LOCKERS_H_
+
+#include "platform/assert.h"
+#include "platform/synchronization.h"
+
+namespace dart {
+namespace platform {
+
+class MutexLocker {
+ public:
+  explicit MutexLocker(Mutex* mutex) : mutex_(mutex) {
+    ASSERT(mutex != nullptr);
+    mutex_->Lock();
+  }
+
+  virtual ~MutexLocker() { mutex_->Unlock(); }
+
+ private:
+  Mutex* const mutex_;
+
+  DISALLOW_COPY_AND_ASSIGN(MutexLocker);
+};
+
+class MonitorLocker {
+ public:
+  explicit MonitorLocker(Monitor* monitor) : monitor_(monitor) {
+    ASSERT(monitor != nullptr);
+    monitor_->Enter();
+  }
+
+  virtual ~MonitorLocker() { monitor_->Exit(); }
+
+  Monitor::WaitResult Wait(int64_t millis = Monitor::kNoTimeout) {
+    return monitor_->Wait(millis);
+  }
+
+  void Notify() { monitor_->Notify(); }
+
+  void NotifyAll() { monitor_->NotifyAll(); }
+
+ private:
+  Monitor* const monitor_;
+
+  DISALLOW_COPY_AND_ASSIGN(MonitorLocker);
+};
+
+}  // namespace platform
+}  // namespace dart
+
+#endif  // RUNTIME_PLATFORM_LOCKERS_H_

runtime/platform/platform_sources.gni

@@ -18,6 +18,7 @@ platform_sources = [
   "growable_array.h",
   "hashmap.cc",
   "hashmap.h",
+  "lockers.h",
   "memory_sanitizer.h",
   "safe_stack.h",
   "signal_blocker.h",