base::RefCounted now DCHECKs when referenced from multiple threads.

sql/connection.h

Index: sql/connection.h
diff --git a/sql/connection.h b/sql/connection.h
index 5bbdb972d63ffcc6a0d3e74615b4e2d6b6474761..b8b1196332a2f6292bdceb7c32cf81e14bb90494 100644
--- a/sql/connection.h
+++ b/sql/connection.h
@@ -459,7 +459,8 @@ class SQL_EXPORT Connection {
   //
   // The Connection may revoke a StatementRef in some error cases, so callers
   // should always check validity before using.
-  class SQL_EXPORT StatementRef : public base::RefCounted<StatementRef> {
+  // TODO(mgiuca): Avoid using UnsafeRefCounted. http://crbug.com/469952.
+  class SQL_EXPORT StatementRef : public base::UnsafeRefCounted<StatementRef> {
    public:
     // |connection| is the sql::Connection instance associated with
     // the statement, and is used for tracking outstanding statements
@@ -498,7 +499,7 @@ class SQL_EXPORT Connection {
     void AssertIOAllowed() { if (connection_) connection_->AssertIOAllowed(); }
 
    private:
-    friend class base::RefCounted<StatementRef>;
+    friend class base::UnsafeRefCounted<StatementRef>;
 
     ~StatementRef();