Use platform sized counters for the refcounted classes in base.

content/common/one_writer_seqlock_unittest.cc

Index: content/common/one_writer_seqlock_unittest.cc
diff --git a/content/common/one_writer_seqlock_unittest.cc b/content/common/one_writer_seqlock_unittest.cc
index 84d5156a7bd6fad617e015519637858593740067..5fb184875f8326c4d2285387500e245db6f478a1 100644
--- a/content/common/one_writer_seqlock_unittest.cc
+++ b/content/common/one_writer_seqlock_unittest.cc
@@ -28,7 +28,7 @@ class BasicSeqLockTestThread : public PlatformThread::Delegate {
   void Init(
       content::OneWriterSeqLock* seqlock,
       TestData* data,
-      base::subtle::Atomic32* ready) {
+      base::AtomicRefCount* ready) {
     seqlock_ = seqlock;
     data_ = data;
     ready_ = ready;