Fix "Set pages" drop crash by changing outside drags to simply add a new URL

chrome/browser/ui/webui/options/startup_pages_handler.cc

Index: chrome/browser/ui/webui/options/startup_pages_handler.cc
diff --git a/chrome/browser/ui/webui/options/startup_pages_handler.cc b/chrome/browser/ui/webui/options/startup_pages_handler.cc
index f58b6bc5c5df534719ff50f2e2a1da22c050fec3..343b2a68a6d775d6c1d28e576b9838ae0d3e3e8b 100644
--- a/chrome/browser/ui/webui/options/startup_pages_handler.cc
+++ b/chrome/browser/ui/webui/options/startup_pages_handler.cc
@@ -151,13 +151,17 @@ void StartupPagesHandler::RemoveStartupPages(const ListValue* args) {
 
 void StartupPagesHandler::AddStartupPage(const ListValue* args) {
   std::string url_string;
-  CHECK_EQ(args->GetSize(), 1U);
   CHECK(args->GetString(0, &url_string));
 
   GURL url = URLFixerUpper::FixupURL(url_string, std::string());
   if (!url.is_valid())
     return;
-  int index = startup_custom_pages_table_model_->RowCount();
+
+  int row_count = startup_custom_pages_table_model_->RowCount();
+  int index;
+  if (!args->GetInteger(1, &index) || index > row_count)
+    index = row_count;
+
   startup_custom_pages_table_model_->Add(index, url);
 }