Introduce flag to disable static popular sites.

components/ntp_tiles/popular_sites_impl.cc

 // Copyright 2015 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 "components/ntp_tiles/popular_sites_impl.h"
 
 #include <stddef.h>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 135 matching lines @@
   }
   site->SetInteger("default_icon_resource", resource_id);
 }
 #endif
 
 // Creates the list of popular sites based on a snapshot available for mobile.
 std::unique_ptr<base::ListValue> DefaultPopularSites() {
 #if !defined(OS_ANDROID) && !defined(OS_IOS)
   return base::MakeUnique<base::ListValue>();
 #else
+  if (!ShouldUseBakedInSites()) {
+    return base::MakeUnique<base::ListValue>();
+  }
   std::unique_ptr<base::ListValue> sites =
       base::ListValue::From(base::JSONReader::Read(
           ResourceBundle::GetSharedInstance().GetRawDataResource(
               IDR_DEFAULT_POPULAR_SITES_JSON)));
   DCHECK(sites);
 #if defined(GOOGLE_CHROME_BUILD)
   int index = 0;
   for (int icon_resource :
        {IDR_DEFAULT_POPULAR_SITES_ICON0, IDR_DEFAULT_POPULAR_SITES_ICON1,
         IDR_DEFAULT_POPULAR_SITES_ICON2, IDR_DEFAULT_POPULAR_SITES_ICON3,
@@ skipping 246 matching lines @@
     pending_url_ = GetPopularSitesURL(kPopularSitesDefaultCountryCode,
                                       kPopularSitesDefaultVersion);
     FetchPopularSites();
   } else {
     DLOG(WARNING) << "Download fallback site list failed";
     callback_.Run(false);
   }
 }
 
 }  // namespace ntp_tiles