Roll forward to cl/333580336

Signed-off-by: Josh Nohle <nohle@google.com>

cpp/platform_v2/impl/ios/mutex.h

@@ -0,0 +1,47 @@
+#ifndef PLATFORM_V2_IMPL_IOS_MUTEX_H_
+#define PLATFORM_V2_IMPL_IOS_MUTEX_H_
+
+#include "platform_v2/api/mutex.h"
+#include "platform_v2/impl/shared/posix_mutex.h"
+#include "absl/synchronization/mutex.h"
+
+namespace location {
+namespace nearby {
+namespace ios {
+
+class ABSL_LOCKABLE Mutex : public api::Mutex {
+ public:
+  explicit Mutex(bool check) : check_(check) {}
+  ~Mutex() override = default;
+  Mutex(Mutex&&) = delete;
+  Mutex& operator=(Mutex&&) = delete;
+  Mutex(const Mutex&) = delete;
+  Mutex& operator=(const Mutex&) = delete;
+
+  void Lock() ABSL_EXCLUSIVE_LOCK_FUNCTION() override {
+    mutex_.Lock();
+    if (!check_) mutex_.ForgetDeadlockInfo();
+  }
+  void Unlock() ABSL_UNLOCK_FUNCTION() override { mutex_.Unlock(); }
+
+ private:
+  friend class ConditionVariable;
+  absl::Mutex mutex_;
+  bool check_;
+};
+
+class ABSL_LOCKABLE RecursiveMutex : public posix::Mutex {
+ public:
+  ~RecursiveMutex() override = default;
+  RecursiveMutex() = default;
+  RecursiveMutex(RecursiveMutex&&) = delete;
+  RecursiveMutex& operator=(RecursiveMutex&&) = delete;
+  RecursiveMutex(const RecursiveMutex&) = delete;
+  RecursiveMutex& operator=(const RecursiveMutex&) = delete;
+};
+
+}  // namespace ios
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_V2_IMPL_IOS_MUTEX_H_