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

sql/test/error_callback_support.cc

+// Copyright 2013 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 "sql/test/error_callback_support.h"
+
+namespace sql {
+
+void CaptureErrorCallback(int* error_pointer, int error, sql::Statement* stmt) {
+  *error_pointer = error;
+}
+
+ScopedErrorCallback::ScopedErrorCallback(
+    sql::Connection* db,
+    const sql::Connection::ErrorCallback& cb)
+    : db_(db) {

[Greg Billock, 2013/06/27 20:27:26]

Any need to check if one has already been set? Perhaps that should be in
connection.h, check error_callback_.is_null ...

[Scott Hess - ex-Googler, 2013/06/27 20:59:45]

Yeah, probably.  I'm inclined towards a DCHECK for now, since I'm not sure if
nesting would be desirable.

[Scott Hess - ex-Googler, 2013/06/28 22:04:37]

A DCHECK would result in moving set_error_callback() from .h to .cc, and then I
think it needs renamed to SetErrorCallback(), in which case consistency probably
wants ResetErrorCallback().

I think that having the scoper displace an existing callback is almost certainly
wrong, but I'm not entirely convinced that a real-world user should be required
to reset the callback before setting a new one.  So I've adjusted things so that
this code EXPECTs to not have an existing callback in place.

+  db_->set_error_callback(cb);
+}
+
+ScopedErrorCallback::~ScopedErrorCallback() {
+  db_->reset_error_callback();
+}
+
+}  // namespace