Notify launcher page with onTransitionChanged event

athena/home/app_list_view_delegate.cc

Index: athena/home/app_list_view_delegate.cc
diff --git a/athena/home/app_list_view_delegate.cc b/athena/home/app_list_view_delegate.cc
index eead245f102a22399a88b3808b7d9042027903be..9eb4a25b2a64e44efbd385e1fdbc35256f013fc5 100644
--- a/athena/home/app_list_view_delegate.cc
+++ b/athena/home/app_list_view_delegate.cc
@@ -159,6 +159,9 @@ std::vector<views::View*> AppListViewDelegate::CreateCustomPageWebViews(
   return std::vector<views::View*>();
 }
 
+void AppListViewDelegate::CustomLauncherPageAnimationChanged(double progress) {
+}
+
 bool AppListViewDelegate::IsSpeechRecognitionEnabled() {
   return false;
 }