Allow multiple sql::Connection error delegates.

sql/connection.cc

Index: sql/connection.cc
diff --git a/sql/connection.cc b/sql/connection.cc
index ea3dacbb6ba025dc248590a40031cc4a508541f4..55d2929e32f9c7a56c619c926ca928d5588bd8d1 100644
--- a/sql/connection.cc
+++ b/sql/connection.cc
@@ -604,8 +604,13 @@ void Connection::ClearCache() {
 }
 
 int Connection::OnSqliteError(int err, sql::Statement *stmt) {
-  if (error_delegate_.get())
-    return error_delegate_->OnError(err, this, stmt);
+  if (!error_delegates_.empty()) {
+    std::vector<scoped_refptr<ErrorDelegate> > delegates = error_delegates_;
+    for (size_t i = 0; err != SQLITE_OK && i < delegates.size(); ++i) {
+      err = delegates[i]->OnError(err, this, stmt);
+    }
+    return err;
+  }
   // The default handling is to assert on debug and to ignore on release.
   DLOG(FATAL) << GetErrorMessage();
   return err;