Start axing NTP4 dead code.

chrome/browser/ui/webui/ntp/new_tab_page_handler.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/webui/ntp/new_tab_page_handler.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/metrics/histogram.h"
@@ skipping 137 matching lines @@
   double duration;
   if (!args->GetString(0, &histogram_name) || !args->GetDouble(1, &duration)) {
     NOTREACHED();
     return;
   }
 
   base::TimeDelta delta = base::TimeDelta::FromMilliseconds(duration);
 
   if (histogram_name == "NewTabPage.TimeToClickMostVisited") {
     UMA_HISTOGRAM_LONG_TIMES("NewTabPage.TimeToClickMostVisited", delta);
-  } else if (histogram_name == "NewTabPage.TimeToClickRecentlyClosed") {
-    UMA_HISTOGRAM_LONG_TIMES("NewTabPage.TimeToClickRecentlyClosed", delta);
   } else if (histogram_name == "ExtendedNewTabPage.TimeToClickMostVisited") {

[Evan Stade, 2015/05/14 19:04:55]

then this one can probably be deleted as well

[Dan Beam, 2015/05/14 19:56:46]

there's a lot more code to go.  this CL is targeted.

     UMA_HISTOGRAM_LONG_TIMES(
         "ExtendedNewTabPage.TimeToClickMostVisited", delta);
-  } else if (histogram_name == "ExtendedNewTabPage.TimeToClickRecentlyClosed") {
-    UMA_HISTOGRAM_LONG_TIMES(
-        "ExtendedNewTabPage.TimeToClickRecentlyClosed", delta);

[Evan Stade, 2015/05/14 00:09:44]

ah! this is one way to verify the code isn't used any more. Check uma to see if
there are any users hitting this bucket. Have you done so?

also, update histograms.xml?

[Dan Beam, 2015/05/14 01:09:34]

can't find it in UMA nor is it in histograms.xml

   } else {
     NOTREACHED();
   }
 }
 
 // static
 void NewTabPageHandler::RegisterProfilePrefs(
     user_prefs::PrefRegistrySyncable* registry) {
   // TODO(estade): should be syncable.
   registry->RegisterIntegerPref(prefs::kNtpShownPage, APPS_PAGE_ID);
@@ skipping 12 matching lines @@
   values->SetInteger("shown_page_index", shown_page & INDEX_MASK);
 }
 
 void NewTabPageHandler::Notify(chrome::NotificationType notification_type) {
   content::NotificationService* service =
       content::NotificationService::current();
   service->Notify(notification_type,
                   content::Source<NewTabPageHandler>(this),
                   content::NotificationService::NoDetails());
 }