[sql] Callback and scoped-ignore tests for sql::Statement.

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 107 matching lines @@
 
   // Set an error-handling callback.  On errors, the error number (and
   // statement, if available) will be passed to the callback.
   //
   // If no callback is set, the default action is to crash in debug
   // mode or return failure in release mode.
   typedef base::Callback<void(int, Statement*)> ErrorCallback;
   void set_error_callback(const ErrorCallback& callback) {
     error_callback_ = callback;
   }
+  bool has_error_callback() const {
+    return !error_callback_.is_null();
+  }
   void reset_error_callback() {
     error_callback_.Reset();
   }
 
   // Set this tag to enable additional connection-type histogramming
   // for SQLite error codes and database version numbers.
   void set_histogram_tag(const std::string& tag) {
     histogram_tag_ = tag;
   }
 
@@ skipping 375 matching lines @@
 
   // Tag for auxiliary histograms.
   std::string histogram_tag_;
 
   DISALLOW_COPY_AND_ASSIGN(Connection);
 };
 
 }  // namespace sql
 
 #endif  // SQL_CONNECTION_H_