MD History: Lazily load element files which are not needed for first paint

chrome/browser/ui/webui/md_history_ui.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 "chrome/browser/ui/webui/md_history_ui.h"
 
 #include "base/command_line.h"
 #include "build/build_config.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/signin/signin_manager_factory.h"
@@ skipping 116 matching lines @@
                           IDR_MD_HISTORY_IMAGES_100_SIGN_IN_PROMO_PNG);
   source->AddResourcePath("images/200/sign_in_promo.png",
                           IDR_MD_HISTORY_IMAGES_200_SIGN_IN_PROMO_PNG);
   source->AddResourcePath("history.js", IDR_MD_HISTORY_HISTORY_JS);
 
 #if BUILDFLAG(USE_VULCANIZE)
   source->AddResourcePath("app.html",
                           IDR_MD_HISTORY_APP_VULCANIZED_HTML);
   source->AddResourcePath("app.crisper.js",
                           IDR_MD_HISTORY_APP_CRISPER_JS);
+  source->AddResourcePath("lazy_load.html",
+                          IDR_MD_HISTORY_LAZY_LOAD_VULCANIZED_HTML);
+  source->AddResourcePath("lazy_load.crisper.js",
+                          IDR_MD_HISTORY_LAZY_LOAD_CRISPER_JS);
 #else
   source->AddResourcePath("app.html", IDR_MD_HISTORY_APP_HTML);
   source->AddResourcePath("app.js", IDR_MD_HISTORY_APP_JS);
   source->AddResourcePath("browser_service.html",
                           IDR_MD_HISTORY_BROWSER_SERVICE_HTML);
   source->AddResourcePath("browser_service.js",
                           IDR_MD_HISTORY_BROWSER_SERVICE_JS);
   source->AddResourcePath("grouped_list.html",
                           IDR_MD_HISTORY_GROUPED_LIST_HTML);
   source->AddResourcePath("grouped_list.js", IDR_MD_HISTORY_GROUPED_LIST_JS);
   source->AddResourcePath("history_item.html",
                           IDR_MD_HISTORY_HISTORY_ITEM_HTML);
   source->AddResourcePath("history_item.js", IDR_MD_HISTORY_HISTORY_ITEM_JS);
   source->AddResourcePath("history_list.html",
                           IDR_MD_HISTORY_HISTORY_LIST_HTML);
   source->AddResourcePath("history_list.js", IDR_MD_HISTORY_HISTORY_LIST_JS);
   source->AddResourcePath("history_list_behavior.html",
                           IDR_MD_HISTORY_HISTORY_LIST_BEHAVIOR_HTML);
   source->AddResourcePath("history_list_behavior.js",
                           IDR_MD_HISTORY_HISTORY_LIST_BEHAVIOR_JS);
   source->AddResourcePath("history_toolbar.html",
                           IDR_MD_HISTORY_HISTORY_TOOLBAR_HTML);
   source->AddResourcePath("history_toolbar.js",
                           IDR_MD_HISTORY_HISTORY_TOOLBAR_JS);
   source->AddResourcePath("icons.html", IDR_MD_HISTORY_ICONS_HTML);
+  source->AddResourcePath("lazy_load.html", IDR_MD_HISTORY_LAZY_LOAD_HTML);
   source->AddResourcePath("list_container.html",
                           IDR_MD_HISTORY_LIST_CONTAINER_HTML);
   source->AddResourcePath("list_container.js",
                           IDR_MD_HISTORY_LIST_CONTAINER_JS);
   source->AddResourcePath("searched_label.html",
                           IDR_MD_HISTORY_SEARCHED_LABEL_HTML);
   source->AddResourcePath("searched_label.js",
                           IDR_MD_HISTORY_SEARCHED_LABEL_JS);
   source->AddResourcePath("shared_style.html",
                           IDR_MD_HISTORY_SHARED_STYLE_HTML);
@@ skipping 52 matching lines @@
   base::FeatureList::ClearInstanceForTesting();
   base::FeatureList::SetInstance(std::move(feature_list));
 }
 
 // static
 base::RefCountedMemory* MdHistoryUI::GetFaviconResourceBytes(
     ui::ScaleFactor scale_factor) {
   return ResourceBundle::GetSharedInstance().LoadDataResourceBytesForScale(
       IDR_HISTORY_FAVICON, scale_factor);
 }