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 097d41593adf896661b44393c58c4b2a8c118da4..047859983ca920158ec7db458b5e0db9cc668954 100644
--- a/chrome/browser/ui/views/frame/instant_overlay_controller_views.cc
+++ b/chrome/browser/ui/views/frame/instant_overlay_controller_views.cc
@@ -5,8 +5,12 @@
 #include "chrome/browser/ui/views/frame/instant_overlay_controller_views.h"
 
 #include "chrome/browser/profiles/profile.h"
+#include "chrome/browser/search/search.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/search/instant_overlay_model.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"
@@ -25,6 +29,10 @@ InstantOverlayControllerViews::~InstantOverlayControllerViews() {
 
 void InstantOverlayControllerViews::OverlayStateChanged(
     const InstantOverlayModel& model) {
+  // Set top bars (bookmark and info bars) visibility if Instant Extended API
+  // is enabled.
+  bool set_top_bars_visibility = chrome::search::IsInstantExtendedAPIEnabled();
+
   if (model.mode().is_ntp() || model.mode().is_search_suggestions()) {
     // Show the overlay.
     if (!overlay_) {
@@ -44,18 +52,26 @@ void InstantOverlayControllerViews::OverlayStateChanged(
     overlay_->SetWebContents(NULL);
     contents_->SetOverlay(NULL, NULL, 100, INSTANT_SIZE_PERCENT, false);
     overlay_.reset();
+  } else {
+    // Don't set top bars visiblility if nothing was done with overlay.
+    set_top_bars_visibility = false;
   }
 
-  browser_->MaybeUpdateBookmarkBarStateForInstantOverlay(model.mode());
+  if (set_top_bars_visibility) {
+    // Set top 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);
-    }
   }
 }