Enable warning 4389 as an error on windows builds. This will make...

base/lock_impl_win.cc

-// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
+// Copyright (c) 2010 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/lock_impl.h"
 #include "base/logging.h"
 
 // NOTE: Although windows critical sections support recursive locks, we do not
 // allow this, and we will commonly fire a DCHECK() if a thread attempts to
 // acquire the lock a second time (while already holding it).
 
@@ skipping 10 matching lines @@
 
 LockImpl::~LockImpl() {
   ::DeleteCriticalSection(&os_lock_);
 }
 
 bool LockImpl::Try() {
   if (::TryEnterCriticalSection(&os_lock_) != FALSE) {
 #ifndef NDEBUG
     // ONLY access data after locking.
     owning_thread_id_ = PlatformThread::CurrentId();
-    DCHECK_NE(owning_thread_id_, 0);
+    DCHECK_NE(owning_thread_id_, 0u);
     recursion_count_shadow_++;
     if (2 == recursion_count_shadow_ && !recursion_used_) {
       recursion_used_ = true;
       DCHECK(false);  // Catch accidental redundant lock acquisition.
     }
 #endif
     return true;
   }
   return false;
 }
 
 void LockImpl::Lock() {
   ::EnterCriticalSection(&os_lock_);
 #ifndef NDEBUG
   // ONLY access data after locking.
   owning_thread_id_ = PlatformThread::CurrentId();
-  DCHECK_NE(owning_thread_id_, 0);
+  DCHECK_NE(owning_thread_id_, 0u);
   recursion_count_shadow_++;
   if (2 == recursion_count_shadow_ && !recursion_used_) {
     recursion_used_ = true;
     DCHECK(false);  // Catch accidental redundant lock acquisition.
   }
 #endif  // NDEBUG
 }
 
 void LockImpl::Unlock() {
 #ifndef NDEBUG
   --recursion_count_shadow_;  // ONLY access while lock is still held.
   DCHECK(0 <= recursion_count_shadow_);
   owning_thread_id_ = 0;
 #endif  // NDEBUG
   ::LeaveCriticalSection(&os_lock_);
 }
 
 // In non-debug builds, this method is declared as an empty inline method.
 #ifndef NDEBUG
 void LockImpl::AssertAcquired() const {
   DCHECK(recursion_count_shadow_ > 0);
   DCHECK_EQ(owning_thread_id_, PlatformThread::CurrentId());
 }
 #endif