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

chrome/browser/infobars/infobar_container.cc

 // Copyright (c) 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 "build/build_config.h"
 
 // TODO(pkasting): Port Mac to use this.
 #if defined(TOOLKIT_VIEWS) || defined(TOOLKIT_GTK)
 
 #include "chrome/browser/infobars/infobar_container.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "chrome/browser/api/infobars/infobar_delegate.h"
 #include "chrome/browser/api/infobars/infobar_service.h"
 #include "chrome/browser/infobars/infobar.h"
 #include "chrome/browser/instant/instant_overlay_model.h"
+#include "chrome/browser/instant/search.h"
 #include "chrome/browser/ui/search/search_model.h"
 #include "chrome/common/chrome_notification_types.h"
 #include "content/public/browser/notification_details.h"
 #include "content/public/browser/notification_source.h"
 #include "ui/base/animation/slide_animation.h"
 
 InfoBarContainer::Delegate::~Delegate() {
 }
 
 InfoBarContainer::InfoBarContainer(
@@ skipping 37 matching lines @@
                    source);
 
     for (size_t i = 0; i < infobar_service_->GetInfoBarCount(); ++i) {
       // As when we removed the infobars above, we prevent callbacks to
       // OnInfoBarAnimated() for each infobar.
       AddInfoBar(
           infobar_service_->GetInfoBarDelegateAt(i)->CreateInfoBar(
               infobar_service_),
           i, false, NO_CALLBACK);
     }
+
+    // Hide infobars if search model requires so.

[Peter Kasting, 2013/03/15 05:32:01]

Don't do this.

Instead, make this function begin as follows:

  infobar_service_ = infobar_service;

  if (!search_model_->top_bars_visible())
    return;

  ...everything from the existing function except the opening RemoveAll() call
and the already-done setting of infobar_service_...

Then add "registrar_.RemoveAll();" to the top of HideAllInfoBars(), and change
the beginning of Observe() to:

  // When infobars are hidden, we shouldn't be listening for notifications.
  DCHECK(infobars_shown_);

[kuan, 2013/03/15 15:53:49]

Done.

[kuan, 2013/03/15 16:32:17]

i moved HideAllInfoBars() to start of function.  correct me if i'm wrong, but i
think we need to do this whenever tab is detached or changed, which is when this
function is called  from outside like BrowserView?

+    if (!search_model_->top_bars_visible())
+      HideAllInfoBars();
   }
 
   // Now that everything is up to date, signal the delegate to re-layout.
   OnInfoBarStateChanged(false);
 }
 
 int InfoBarContainer::GetVerticalOverlap(int* total_height) {
   // Our |total_height| is the sum of the preferred heights of the InfoBars
   // contained within us plus the |vertical_overlap|.
   int vertical_overlap = 0;
@@ skipping 81 matching lines @@
           HideInfoBar(replaced_details->first, false), false, WANT_CALLBACK);
       break;
     }
 
     default:
       NOTREACHED();
       break;
   }
 }
 
-void InfoBarContainer::ModeChanged(const chrome::search::Mode& old_mode,
-                                   const chrome::search::Mode& new_mode) {
-  // Hide infobars when showing Instant Extended suggestions.
-  if (new_mode.is_search_suggestions()) {
-    // If suggestions are being shown on a |DEFAULT| page, delay the hiding
-    // until notification that Instant overlay is ready is received via
-    // OverlayStateChanged(); this prevents jankiness caused by infobars hiding
-    // followed by suggestions appearing.
-    if (new_mode.is_origin_default())
-      return;
-    HideAllInfoBars();
-    OnInfoBarStateChanged(false);
-  } else {
+void InfoBarContainer::ModelChanged(
+    const chrome::search::SearchModel::State& old_state,
+    const chrome::search::SearchModel::State& new_state) {
+  if (!chrome::search::SearchModel::ShouldChangeTopBarsVisibility(old_state,
+                                                                  new_state)) {

[Peter Kasting, 2013/03/15 05:32:01]

Nit: No {}

[kuan, 2013/03/15 15:53:49]

Done.

+    return;
+  }
+
+  if (new_state.top_bars_visible && !infobars_shown_) {
     ChangeInfoBarService(infobar_service_);
     infobars_shown_time_ = base::TimeTicks::Now();
-  }
-}
-
-void InfoBarContainer::OverlayStateChanged(const InstantOverlayModel& model) {
-  // If suggestions are being shown on a |DEFAULT| page, hide the infobars now.
-  // See comments for ModeChanged() for explanation.
-  if (model.mode().is_search_suggestions() &&
-      model.mode().is_origin_default()) {
+  } else if (!new_state.top_bars_visible && infobars_shown_) {
     HideAllInfoBars();
     OnInfoBarStateChanged(false);
   }
 }
 
 size_t InfoBarContainer::HideInfoBar(InfoBarDelegate* delegate,
                                      bool use_animation) {
   bool should_animate = use_animation &&
       ((base::TimeTicks::Now() - infobars_shown_time_) >
           base::TimeDelta::FromMilliseconds(50));
@@ skipping 61 matching lines @@
     return InfoBar::kDefaultArrowTargetHeight;
   // When the first infobar is animating closed, we animate the second infobar's
   // arrow target height from the default to the top target height.  Note that
   // the animation values here are going from 1.0 -> 0.0 as the top bar closes.
   return top_arrow_target_height_ + static_cast<int>(
       (InfoBar::kDefaultArrowTargetHeight - top_arrow_target_height_) *
           first_infobar_animation.GetCurrentValue());
 }
 
 #endif  // TOOLKIT_VIEWS || defined(TOOLKIT_GTK)