Move the sqlite error handler to a single location...

chrome/browser/diagnostics/sqlite_diagnostics.cc

 // Copyright (c) 2009 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.
 
 #include "chrome/browser/diagnostics/sqlite_diagnostics.h"
 
+#include "app/sql/connection.h"
+#include "base/histogram.h"
+#include "base/logging.h"
+#include "base/singleton.h"
+
+namespace {
+
+const char* kHistogramNames[] = {
+  "Sqlite.Cookie.Error",
+  "Sqlite.History.Error",
+  "Sqlite.Thumbnail.Error",
+  "Sqlite.Text.Error",
+  "Sqlite.Web.Error"

[jar (doing other things), 2009/10/15 06:44:28]

Not a big deal... but... Given these will be sorted with other Sqlite.*
histograms, you might prefer to get them bunched together by naming them:
Sqlite.Error.Cookie
Sqlite.Error.History
etc.

+};
+
+// 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 <size_t unique>
+class BasicSqliteErrrorHandler : public sql::ErrorDelegate {
+ public:
+
+  virtual int OnError(int error, sql::Connection* connection,
+                      sql::Statement* stmt) {
+    NOTREACHED() << "sqlite error " << error;
+    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.
+    static LinearHistogram histogram(kHistogramNames[unique], 1, 50, 51);
+    histogram.SetFlags(kUmaTargetedHistogramFlag);
+    histogram.Add(error);
+  }
+};
+
+}  // namespace
+
+sql::ErrorDelegate* GetErrorHandlerForCookieDb() {
+  return new BasicSqliteErrrorHandler<0>();
+}
+
+sql::ErrorDelegate* GetErrorHandlerForHistoryDb() {
+  return new BasicSqliteErrrorHandler<1>();
+}
+
+sql::ErrorDelegate* GetErrorHandlerForThumbnailDb() {
+  return new BasicSqliteErrrorHandler<2>();
+}
+
+sql::ErrorDelegate* GetErrorHandlerForTextDb() {
+  return new BasicSqliteErrrorHandler<3>();
+}
+
+sql::ErrorDelegate* GetErrorHandlerForWebDb() {
+  return new BasicSqliteErrrorHandler<4>();
+}