Move ErrorDelegate to its own file and add static utility functions to ErrorDelegate

sql/error_delegate_util.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_ERROR_DELEGATE_UTIL_H_
+#define SQL_ERROR_DELEGATE_UTIL_H_
+
+#include "base/metrics/histogram.h"
+#include "sql/connection.h"
+#include "sql/sql_export.h"
+
+namespace sql {
+
+// Returns true if it is highly unlikely that the database can recover from
+// |error|.
+SQL_EXPORT bool IsErrorCatastrophic(int error);
+
+// Log error in console in debug mode and generate a UMA histogram in release
+// mode for |error| for |UniqueT::name()|.
+// This function is templated because histograms need to be singletons. That is
+// why they are always static at the function scope. The template parameter
+// makes the compiler create unique functions that don't share the same static
+// variable.
+template <class UniqueT>
+void LogAndRecordErrorInHistogram(int error,
+                                  sql::Connection* connection) {
+  LOG(ERROR) << "sqlite error " << error
+             << ", errno " << connection->GetLastErrno()
+             << ": " << connection->GetErrorMessage();
+
+  // Trim off the extended error codes.
+  error &= 0xff;
+
+  // The histogram values from sqlite result codes currently go from 1 to 26
+  // but 50 gives them room to grow.
+  UMA_HISTOGRAM_ENUMERATION(UniqueT::name(), error, 50);
+}
+
+}  // namespace sql
+
+#endif  // SQL_ERROR_DELEGATE_UTIL_H_