Avoid IndexedDBClient::create() read race.

third_party/WebKit/Source/modules/indexeddb/IndexedDBClient.cpp

Index: third_party/WebKit/Source/modules/indexeddb/IndexedDBClient.cpp
diff --git a/third_party/WebKit/Source/modules/indexeddb/IndexedDBClient.cpp b/third_party/WebKit/Source/modules/indexeddb/IndexedDBClient.cpp
index 54f9f5eba241df40b4cf95ba9bff6c4cf9c0d317..ddbe4cd3a088f29fdb4fd10eed1cf2db736ede51 100644
--- a/third_party/WebKit/Source/modules/indexeddb/IndexedDBClient.cpp
+++ b/third_party/WebKit/Source/modules/indexeddb/IndexedDBClient.cpp
@@ -20,10 +20,11 @@ void setIndexedDBClientCreateFunction(CreateIndexedDBClient createFunction)
 
 IndexedDBClient* IndexedDBClient::create()
 {
-    ASSERT(idbClientCreateFunction);
+    CreateIndexedDBClient* createFunction = reinterpret_cast<CreateIndexedDBClient*>(acquireLoad(&idbClientCreateFunction));
+    ASSERT(createFunction);
     // There's no reason why we need to allocate a new proxy each time, but
     // there's also no strong reason not to.
-    return reinterpret_cast<CreateIndexedDBClient*>(idbClientCreateFunction)();
+    return createFunction();
 }
 
 } // namespace blink