Roll forward to cl/338482889

Signed-off-by: Alexey Polyudov <apolyudov@google.com>
Change-Id: I9850950db8bd84f0904ea1a413151887f52098cf

cpp/platform/impl/shared/posix_mutex.cc

@@ -0,0 +1,26 @@
+#include "platform/impl/shared/posix_mutex.h"
+
+namespace location {
+namespace nearby {
+namespace posix {
+
+Mutex::Mutex() : attr_(), mutex_() {
+  pthread_mutexattr_init(&attr_);
+  pthread_mutexattr_settype(&attr_, PTHREAD_MUTEX_RECURSIVE);
+
+  pthread_mutex_init(&mutex_, &attr_);
+}
+
+Mutex::~Mutex() {
+  pthread_mutex_destroy(&mutex_);
+
+  pthread_mutexattr_destroy(&attr_);
+}
+
+void Mutex::Lock() { pthread_mutex_lock(&mutex_); }
+
+void Mutex::Unlock() { pthread_mutex_unlock(&mutex_); }
+
+}  // namespace posix
+}  // namespace nearby
+}  // namespace location