Make LockImpl::Unlock available for inlining

base/synchronization/lock_impl_win.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/synchronization/lock_impl.h"
 
 #include "base/debug/activity_tracker.h"
 
 namespace base {
 namespace internal {
 
 LockImpl::LockImpl() : native_handle_(SRWLOCK_INIT) {}
 
 LockImpl::~LockImpl() = default;
 
 bool LockImpl::Try() {
   return !!::TryAcquireSRWLockExclusive(&native_handle_);
 }
 
 void LockImpl::Lock() {
   base::debug::ScopedLockAcquireActivity lock_activity(this);
   ::AcquireSRWLockExclusive(&native_handle_);
 }
 
-void LockImpl::Unlock() {
-  ::ReleaseSRWLockExclusive(&native_handle_);
-}
-
 }  // namespace internal
 }  // namespace base