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

sql/connection.h

 // Copyright (c) 2012 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.
 
 #ifndef SQL_CONNECTION_H_
 #define SQL_CONNECTION_H_
 
 #include <map>
 #include <set>
 #include <string>
@@ skipping 441 matching lines @@
   // Refcounting allows us to give these statements out to sql::Statement
   // objects while also optionally maintaining a cache of compiled statements
   // by just keeping a refptr to these objects.
   //
   // A statement ref can be valid, in which case it can be used, or invalid to
   // indicate that the statement hasn't been created yet, has an error, or has
   // been destroyed.
   //
   // 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
     // and for error handling.  Set to NULL for invalid or untracked
     // refs.  |stmt| is the actual statement, and should only be NULL
     // to create an invalid ref.  |was_valid| indicates whether the
     // statement should be considered valid for diagnistic purposes.
     // |was_valid| can be true for NULL |stmt| if the connection has
     // been forcibly closed by an error handler.
     StatementRef(Connection* connection, sqlite3_stmt* stmt, bool was_valid);
@@ skipping 18 matching lines @@
     // Destroys the compiled statement and marks it NULL. The statement will
     // no longer be active.  |forced| is used to indicate if orderly-shutdown
     // checks should apply (see Connection::RazeAndClose()).
     void Close(bool forced);
 
     // Check whether the current thread is allowed to make IO calls, but only
     // if database wasn't open in memory.
     void AssertIOAllowed() { if (connection_) connection_->AssertIOAllowed(); }
 
    private:
-    friend class base::RefCounted<StatementRef>;
+    friend class base::UnsafeRefCounted<StatementRef>;
 
     ~StatementRef();
 
     Connection* connection_;
     sqlite3_stmt* stmt_;
     bool was_valid_;
 
     DISALLOW_COPY_AND_ASSIGN(StatementRef);
   };
   friend class StatementRef;
@@ skipping 80 matching lines @@
 
   // Tag for auxiliary histograms.
   std::string histogram_tag_;
 
   DISALLOW_COPY_AND_ASSIGN(Connection);
 };
 
 }  // namespace sql
 
 #endif  // SQL_CONNECTION_H_