alternate ntp: fix website page jankiness when suggestions show and top bars are hidden

chrome/browser/ui/browser.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/browser.h"
 
 #if defined(OS_WIN)
 #include <windows.h>
 #include <shellapi.h>
 #endif  // defined(OS_WIN)
@@ skipping 1226 matching lines @@
 void Browser::ShowFirstRunBubble() {
   window()->GetLocationBar()->ShowFirstRunBubble();
 }
 
 void Browser::MaybeUpdateBookmarkBarStateForInstantPreview(
     const chrome::search::Mode& mode) {
   // This is invoked by a platform-specific implementation of
   // |InstantPreviewController| to update bookmark bar state according to
   // instant preview state.
   // ModeChanged() updates bookmark bar state for all mode transitions except
-  // when transitioning from |NTP| to |SEARCH_SUGGESTIONS|, because that needs
-  // to be done when the suggestions are ready.
-  // If |mode| is |SEARCH_SUGGESTIONS| and bookmark bar is still showing
-  // attached, the previous mode is definitely NTP; it won't be |DEFAULT|
-  // because ModeChanged() would have handled that transition by hiding the
-  // bookmark bar.
+  // when new mode is |SEARCH_SUGGESTIONS|, because that needs to be done when
+  // the suggestions are ready.
   if (mode.is_search_suggestions() &&
       bookmark_bar_state_ == BookmarkBar::SHOW) {
     UpdateBookmarkBarState(BOOKMARK_BAR_STATE_CHANGE_TAB_STATE);
   }
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 // Browser, content::WebContentsDelegate implementation:
 
 WebContents* Browser::OpenURLFromTab(WebContents* source,
@@ skipping 643 matching lines @@
       UpdateBookmarkBarState(BOOKMARK_BAR_STATE_CHANGE_TAB_STATE);
       break;
 
     default:
       NOTREACHED() << "Got a notification we didn't register for.";
   }
 }
 
 void Browser::ModeChanged(const chrome::search::Mode& old_mode,
                           const chrome::search::Mode& new_mode) {
-  // If mode is transitioning from |NTP| to |SEARCH_SUGGESTIONS|, don't update
-  // bookmark bar state now; wait till the instant preview is ready to show
-  // suggestions before starting the animation to hide the bookmark bar (in
-  // MaybeUpdateBookmarkBarStateForInstantPreview()).
+  // If new mode is |SEARCH_SUGGESTIONS|, don't update bookmark bar state now;
+  // wait till the instant preview is ready to show suggestions before hiding
+  // the bookmark bar (in MaybeUpdateBookmarkBarStateForInstantPreview()).
+  // TODO(kuan): but for now, only delay updating bookmark bar state if origin
+  // is |DEFAULT|; other origins require more complex logic to be implemented
+  // to prevent jankiness caused by hiding bookmark bar, so just hide the
+  // bookmark bar immediately and tolerate the jankiness for a while.
   // For other mode transitions, update bookmark bar state accordingly.
-  if (old_mode.is_ntp() && new_mode.is_search_suggestions() &&
+  if (new_mode.is_search_suggestions() &&
+      new_mode.is_origin_default() &&
       bookmark_bar_state_ == BookmarkBar::SHOW) {
     return;
   }
   UpdateBookmarkBarState(BOOKMARK_BAR_STATE_CHANGE_TAB_STATE);
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 // Browser, Command and state updating (private):
 
 void Browser::OnDevToolsDisabledChanged() {
@@ skipping 406 matching lines @@
   if (contents && !allow_js_access) {
     contents->web_contents()->GetController().LoadURL(
         target_url,
         content::Referrer(),
         content::PAGE_TRANSITION_LINK,
         std::string());  // No extra headers.
   }
 
   return contents != NULL;
 }