[Reland] Refactor WebappRegistry into a singleton instance.

chrome/browser/browsing_data/browsing_data_remover.h

Index: chrome/browser/browsing_data/browsing_data_remover.h
diff --git a/chrome/browser/browsing_data/browsing_data_remover.h b/chrome/browser/browsing_data/browsing_data_remover.h
index 44f8aa06cade1dcab278a72fbf0290babbd4f953..3a2f381aef3431079a82f66737fb60ca0803b805 100644
--- a/chrome/browser/browsing_data/browsing_data_remover.h
+++ b/chrome/browser/browsing_data/browsing_data_remover.h
@@ -460,12 +460,6 @@ class BrowsingDataRemover : public KeyedService
   // Callback on UI thread when the precache history has been cleared.
   void OnClearedPrecacheHistory();
 
-  // Callback on UI thread when the webapp data has been cleared.
-  void OnClearedWebappData();
-
-  // Callback on UI thread when the webapp history has been cleared.
-  void OnClearedWebappHistory();
-
   // Callback on UI thread when the offline page data has been cleared.
   void OnClearedOfflinePageData(
       offline_pages::OfflinePageModel::DeletePageResult result);
@@ -542,8 +536,6 @@ class BrowsingDataRemover : public KeyedService
   bool waiting_for_clear_pnacl_cache_ = false;
 #if BUILDFLAG(ANDROID_JAVA_UI)
   bool waiting_for_clear_precache_history_ = false;
-  bool waiting_for_clear_webapp_data_ = false;
-  bool waiting_for_clear_webapp_history_ = false;
   bool waiting_for_clear_offline_page_data_ = false;
 #endif
   bool waiting_for_clear_storage_partition_data_ = false;