alternate ntp: implement Show/HideBars API to reduce jank when showing/hiding bars

chrome/browser/ui/views/frame/instant_overlay_controller_views.cc

Index: chrome/browser/ui/views/frame/instant_overlay_controller_views.cc
diff --git a/chrome/browser/ui/views/frame/instant_overlay_controller_views.cc b/chrome/browser/ui/views/frame/instant_overlay_controller_views.cc
index ef8fdbbe479d84dc107a6eeef338cad1dbc910d0..16a13396efdacc82ef25feb43973fd7da79c77c1 100644
--- a/chrome/browser/ui/views/frame/instant_overlay_controller_views.cc
+++ b/chrome/browser/ui/views/frame/instant_overlay_controller_views.cc
@@ -7,6 +7,9 @@
 #include "chrome/browser/instant/instant_overlay_model.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/browser.h"
+#include "chrome/browser/ui/search/search_model.h"
+#include "chrome/browser/ui/search/search_tab_helper.h"
+#include "chrome/browser/ui/tabs/tab_strip_model.h"
 #include "chrome/browser/ui/view_ids.h"
 #include "chrome/browser/ui/views/frame/browser_view.h"
 #include "chrome/browser/ui/views/frame/contents_container.h"
@@ -46,16 +49,20 @@ void InstantOverlayControllerViews::OverlayStateChanged(
     overlay_.reset();
   }
 
-  browser_->MaybeUpdateBookmarkBarStateForInstantOverlay(model.mode());
+  // Set top bars (bookmark and info bars) visibility for current tab via
+  // |SearchTabHelper| of current active web contents: top bars are hidden if
+  // there's overlay.
+  chrome::search::SearchTabHelper* search_tab_helper =
+      chrome::search::SearchTabHelper::FromWebContents(
+          browser_->tab_strip_model()->GetActiveWebContents());
+  if (search_tab_helper)
+    search_tab_helper->model()->SetTopBarsVisible(!overlay_);
 
   // If an Instant overlay is added during an immersive mode reveal, the reveal
   // view needs to stay on top.
-  // Notify infobar container of change in overlay state.
   if (overlay_) {
     BrowserView* browser_view = BrowserView::GetBrowserViewForBrowser(browser_);
-    if (browser_view) {
+    if (browser_view)
       browser_view->MaybeStackImmersiveRevealAtTop();
-      browser_view->infobar_container()->OverlayStateChanged(model);
-    }
   }
 }