Make opening a new tab with the NTP use PAGE_TRANSITION_AUTO_TOPLEVEL.

chrome/browser/ui/browser_tabstrip.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 "chrome/browser/ui/browser_tabstrip.h"
 
 #include "base/command_line.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_navigator.h"
 #include "chrome/browser/ui/browser_navigator_params.h"
 #include "chrome/browser/ui/tab_contents/core_tab_helper.h"
 #include "chrome/browser/ui/tabs/tab_strip_model.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/url_constants.h"
 #include "content/public/browser/navigation_entry.h"
 #include "content/public/browser/render_view_host.h"
 #include "content/public/browser/web_contents.h"
 
 namespace chrome {
 
 void AddTabAt(Browser* browser, const GURL& url, int idx, bool foreground) {
   // Time new tab page creation time.  We keep track of the timing data in
   // WebContents, but we want to include the time it takes to create the
   // WebContents object too.
   base::TimeTicks new_tab_start_time = base::TimeTicks::Now();
+  bool show_ntp = url.is_empty();
   chrome::NavigateParams params(browser,
-      url.is_empty() ? GURL(chrome::kChromeUINewTabURL) : url,
-      ui::PAGE_TRANSITION_TYPED);
+      show_ntp ? GURL(chrome::kChromeUINewTabURL) : url,
+      show_ntp ? ui::PAGE_TRANSITION_AUTO_TOPLEVEL : ui::PAGE_TRANSITION_TYPED);
   params.disposition = foreground ? NEW_FOREGROUND_TAB : NEW_BACKGROUND_TAB;
   params.tabstrip_index = idx;
+  // Explicitly ensure new tabs will return to the previous focused tabs when

[msw, 2016/02/02 01:57:46]

nit: "Ensure the previously active tab regains focus when the new tab closes."

+  // closed.
+  if (show_ntp)

[msw, 2016/02/02 01:57:46]

Why is this only applied if |show_ntp| is true? (doesn't that run counter to the
alt+enter test case or other cases with urls, like 'open link in new tab'?) I
wonder if this really is the right fix, and kinda wonder why we don't always
default to this behavior. Can you seek a reviewer with more experience here?

+    params.tabstrip_add_types |= TabStripModel::ADD_INHERIT_GROUP;
+
   chrome::Navigate(&params);
   CoreTabHelper* core_tab_helper =
       CoreTabHelper::FromWebContents(params.target_contents);
   core_tab_helper->set_new_tab_start_time(new_tab_start_time);
 }
 
 content::WebContents* AddSelectedTabWithURL(
     Browser* browser,
     const GURL& url,
     ui::PageTransition transition) {
@@ skipping 36 matching lines @@
     return;
   }
 
   browser->tab_strip_model()->CloseWebContentsAt(
       index,
       add_to_history ? TabStripModel::CLOSE_CREATE_HISTORICAL_TAB
                      : TabStripModel::CLOSE_NONE);
 }
 
 }  // namespace chrome