Add multiple selection support to chooser on desktops

chrome/browser/chooser_controller/chooser_controller.cc

Index: chrome/browser/chooser_controller/chooser_controller.cc
diff --git a/chrome/browser/chooser_controller/chooser_controller.cc b/chrome/browser/chooser_controller/chooser_controller.cc
index af4c28f8ce14f343f9a41392d943cded050fe30c..6bca41ef808b92d1ec5dd8d27e62cba548a82700 100644
--- a/chrome/browser/chooser_controller/chooser_controller.cc
+++ b/chrome/browser/chooser_controller/chooser_controller.cc
@@ -56,6 +56,10 @@ bool ChooserController::ShouldShowIconBeforeText() const {
   return false;
 }
 
+bool ChooserController::AllowMultipleSelection() const {
+  return false;
+}
+
 int ChooserController::GetSignalStrengthLevel(size_t index) const {
   return -1;
 }