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diff --git a/app/sql/diagnostic_error_delegate.h b/app/sql/diagnostic_error_delegate.h
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+// Copyright (c) 2010 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 APP_SQL_DIAGNOSTIC_ERROR_DELEGATE_H_
+#define APP_SQL_DIAGNOSTIC_ERROR_DELEGATE_H_
+
+#include "app/sql/connection.h"
+#include "base/histogram.h"
+#include "base/logging.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.
+//
+// Why is it a template you ask? well, that is a funny story. The histograms
+// need to be singletons that is why they are always static at the function
+// scope, but we cannot use the Singleton class because they are not default
+// constructible. The template parameter makes the compiler to create unique
+// classes that don't share the same static variable.
+template <class UniqueT>
+class DiagnosticErrorDelegate : public ErrorDelegate {
+ public:
+
+  virtual int OnError(int error, Connection* connection,
+                      Statement* stmt) {
+    NOTREACHED() << "sqlite error " << error << ": " <<
+        connection->GetErrorMessage();
+    RecordErrorInHistogram(error);
+    return error;
+  }
+
+ private:
+  static void RecordErrorInHistogram(int error) {
+    // The histogram values from sqlite result codes go currently from 1 to
+    // 26 currently but 50 gives them room to grow.
+    UMA_HISTOGRAM_ENUMERATION(UniqueT::name(), error, 50);
+  }
+};
+
+}  // namespace sql
+
+#endif  // APP_SQL_DIAGNOSTIC_ERROR_DELEGATE_H_