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

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

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/views/frame/instant_overlay_controller_views.h"
 
 #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"
 #include "chrome/browser/ui/views/infobars/infobar_container_view.h"
 #include "ui/views/controls/webview/webview.h"
 
 InstantOverlayControllerViews::InstantOverlayControllerViews(
     Browser* browser,
     ContentsContainer* contents)
     : InstantOverlayController(browser),
@@ skipping 19 matching lines @@
     contents_->SetOverlay(overlay_.get(), web_contents, model.height(),
                           model.height_units(), draw_drop_shadow);
     overlay_->SetWebContents(web_contents);
   } else if (overlay_) {
     // Hide the overlay. SetWebContents() must happen before SetOverlay().
     overlay_->SetWebContents(NULL);
     contents_->SetOverlay(NULL, NULL, 100, INSTANT_SIZE_PERCENT, false);
     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);
-    }
   }
 }