Deleted AppListViewDelegateObserver class (was unused).

chrome/browser/ui/app_list/app_list_view_delegate.h

Index: chrome/browser/ui/app_list/app_list_view_delegate.h
diff --git a/chrome/browser/ui/app_list/app_list_view_delegate.h b/chrome/browser/ui/app_list/app_list_view_delegate.h
index a1a27726afd009a76fe8133cfb22ef53210febaa..427ffe9cb272328f32146c6a8c11e7a9c92b9393 100644
--- a/chrome/browser/ui/app_list/app_list_view_delegate.h
+++ b/chrome/browser/ui/app_list/app_list_view_delegate.h
@@ -15,7 +15,6 @@
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_vector.h"
-#include "base/observer_list.h"
 #include "base/scoped_observer.h"
 #include "chrome/browser/profiles/profile_attributes_storage.h"
 #include "chrome/browser/search/hotword_client.h"
@@ -112,8 +111,6 @@ class AppListViewDelegate : public app_list::AppListViewDelegate,
 #endif
   bool IsSpeechRecognitionEnabled() override;
   const Users& GetUsers() const override;
-  void AddObserver(app_list::AppListViewDelegateObserver* observer) override;
-  void RemoveObserver(app_list::AppListViewDelegateObserver* observer) override;
 
   // Overridden from TemplateURLServiceObserver:
   void OnTemplateURLServiceChanged() override;
@@ -192,8 +189,6 @@ class AppListViewDelegate : public app_list::AppListViewDelegate,
   std::unique_ptr<AppSyncUIStateWatcher> app_sync_ui_state_watcher_;
 #endif
 
-  base::ObserverList<app_list::AppListViewDelegateObserver> observers_;
-
   ScopedObserver<TemplateURLService, AppListViewDelegate>
       template_url_service_observer_;