Remove last client of sql::DiagnosticErrorDelegate.

sql/diagnostic_error_delegate.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_DIAGNOSTIC_ERROR_DELEGATE_H_
-#define SQL_DIAGNOSTIC_ERROR_DELEGATE_H_
-
-#include "base/logging.h"
-#include "sql/connection.h"
-#include "sql/error_delegate_util.h"
-#include "sql/sql_export.h"
-
-namespace sql {
-
-// This class handles the exceptional sqlite errors that we might encounter
-// if for example the db is corrupted. Right now we just generate a UMA
-// histogram for release and an assert for debug builds.
-// See error_delegate_util.h for an explanation as to why this class is a
-// template.
-template <class UniqueT>
-class DiagnosticErrorDelegate : public ErrorDelegate {
- public:
-  DiagnosticErrorDelegate() {}
-  virtual ~DiagnosticErrorDelegate() {}
-
-  virtual int OnError(int error, Connection* connection,
-                      Statement* stmt) {
-    LogAndRecordErrorInHistogram<UniqueT>(error, connection);
-    return error;
-  }
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(DiagnosticErrorDelegate);
-};
-
-}  // namespace sql
-
-#endif  // SQL_DIAGNOSTIC_ERROR_DELEGATE_H_