Standardize usage of virtual/override/final specifiers.

ui/app_list/views/start_page_view.cc

Index: ui/app_list/views/start_page_view.cc
diff --git a/ui/app_list/views/start_page_view.cc b/ui/app_list/views/start_page_view.cc
index 580c986bb5d70af8f265f94ddb253b5fb8d627e6..a13d8ad032e7f8a25cbc3af07cf9733bdc456e8c 100644
--- a/ui/app_list/views/start_page_view.cc
+++ b/ui/app_list/views/start_page_view.cc
@@ -50,10 +50,10 @@ class DummySearchBoxView : public SearchBoxView {
       : SearchBoxView(delegate, view_delegate) {
   }
 
-  virtual ~DummySearchBoxView() {}
+  ~DummySearchBoxView() override {}
 
   // Overridden from views::View:
-  virtual gfx::Size GetPreferredSize() const override {
+  gfx::Size GetPreferredSize() const override {
     gfx::Size size(SearchBoxView::GetPreferredSize());
     size.set_width(kDummySearchBoxWidth);
     return size;