clang/win: Let some chromium_code targets build with -Wextra.

base/threading/thread_local_storage.cc

 // Copyright 2014 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/threading/thread_local_storage.h"
 
 #include "base/atomicops.h"
 #include "base/logging.h"
 
 using base::internal::PlatformThreadLocalStorage;
@@ skipping 58 matching lines @@
     if (key == PlatformThreadLocalStorage::TLS_KEY_OUT_OF_INDEXES) {
       PlatformThreadLocalStorage::TLSKey tmp = key;
       CHECK(PlatformThreadLocalStorage::AllocTLS(&key) &&
             key != PlatformThreadLocalStorage::TLS_KEY_OUT_OF_INDEXES);
       PlatformThreadLocalStorage::FreeTLS(tmp);
     }
     // Atomically test-and-set the tls_key.  If the key is
     // TLS_KEY_OUT_OF_INDEXES, go ahead and set it.  Otherwise, do nothing, as
     // another thread already did our dirty work.
     if (PlatformThreadLocalStorage::TLS_KEY_OUT_OF_INDEXES !=
-        base::subtle::NoBarrier_CompareAndSwap(&g_native_tls_key,
-            PlatformThreadLocalStorage::TLS_KEY_OUT_OF_INDEXES, key)) {
+        static_cast<PlatformThreadLocalStorage::TLSKey>(
+            base::subtle::NoBarrier_CompareAndSwap(
+                &g_native_tls_key,
+                PlatformThreadLocalStorage::TLS_KEY_OUT_OF_INDEXES, key))) {
       // We've been shortcut. Another thread replaced g_native_tls_key first so
       // we need to destroy our index and use the one the other thread got
       // first.
       PlatformThreadLocalStorage::FreeTLS(key);
       key = base::subtle::NoBarrier_Load(&g_native_tls_key);
     }
   }
   CHECK(!PlatformThreadLocalStorage::GetTLSValue(key));
 
   // Some allocators, such as TCMalloc, make use of thread local storage.
@@ skipping 149 matching lines @@
       PlatformThreadLocalStorage::GetTLSValue(
           base::subtle::NoBarrier_Load(&g_native_tls_key)));
   if (!tls_data)
     tls_data = ConstructTlsVector();
   DCHECK_GT(slot_, 0);
   DCHECK_LT(slot_, kThreadLocalStorageSize);
   tls_data[slot_] = value;
 }
 
 }  // namespace base