Added HALF, FULLSCREEN_ALL_APPS, and FULLSCREEN_SEARCH.

ash/app_list/app_list_presenter_delegate.h

Index: ash/app_list/app_list_presenter_delegate.h
diff --git a/ash/app_list/app_list_presenter_delegate.h b/ash/app_list/app_list_presenter_delegate.h
index e7cfcf4b6736b0c9b00cf9e82e2c8e980532cd3f..52856d61ab1956cf22ae7143207547135d8ed62c 100644
--- a/ash/app_list/app_list_presenter_delegate.h
+++ b/ash/app_list/app_list_presenter_delegate.h
@@ -66,6 +66,8 @@ class ASH_EXPORT AppListPresenterDelegate
 
   // ShellObserver overrides:
   void OnOverviewModeStarting() override;
+  void OnMaximizeModeStarted() override;
+  void OnMaximizeModeEnded() override;
 
   // Whether the app list is visible (or in the process of being shown).
   bool is_visible_ = false;