make debug mode ~20% faster on linux

base/synchronization/lock.cc

Index: base/synchronization/lock.cc
diff --git a/base/synchronization/lock.cc b/base/synchronization/lock.cc
index 49efbe926517342f079959386c2103295ddda0f9..7c7ee9dc5a966f30229f1ed198ef2f5b7e9dd510 100644
--- a/base/synchronization/lock.cc
+++ b/base/synchronization/lock.cc
@@ -13,34 +13,25 @@
 
 namespace base {
 
-const PlatformThreadId kNoThreadId = static_cast<PlatformThreadId>(0);
-
 Lock::Lock() : lock_() {
-  owned_by_thread_ = false;
-  owning_thread_id_ = kNoThreadId;
 }
 
 Lock::~Lock() {
-  DCHECK(!owned_by_thread_);
-  DCHECK_EQ(kNoThreadId, owning_thread_id_);
+  DCHECK(owning_thread_ref_.is_null());
 }
 
 void Lock::AssertAcquired() const {
-  DCHECK(owned_by_thread_);
-  DCHECK_EQ(owning_thread_id_, PlatformThread::CurrentId());
+  DCHECK(owning_thread_ref_ == PlatformThread::CurrentRef());
 }
 
 void Lock::CheckHeldAndUnmark() {
-  DCHECK(owned_by_thread_);
-  DCHECK_EQ(owning_thread_id_, PlatformThread::CurrentId());
-  owned_by_thread_ = false;
-  owning_thread_id_ = kNoThreadId;
+  DCHECK(owning_thread_ref_ == PlatformThread::CurrentRef());
+  owning_thread_ref_ = PlatformThreadRef();
 }
 
 void Lock::CheckUnheldAndMark() {
-  DCHECK(!owned_by_thread_);
-  owned_by_thread_ = true;
-  owning_thread_id_ = PlatformThread::CurrentId();
+  DCHECK(owning_thread_ref_.is_null());
+  owning_thread_ref_ = PlatformThread::CurrentRef();
 }
 
 }  // namespace base