Revert of Make extensions DSE persistent in browser prefs

components/search_engines/default_search_manager.h

Index: components/search_engines/default_search_manager.h
diff --git a/components/search_engines/default_search_manager.h b/components/search_engines/default_search_manager.h
index 830bebb93286b0ff3cf8e1732255c7b6ea349dc7..aadc6a4648952a740881931ea7ac2c7fed629882 100644
--- a/components/search_engines/default_search_manager.h
+++ b/components/search_engines/default_search_manager.h
@@ -99,6 +99,14 @@
   // Write default search provider data to |pref_service_|.
   void SetUserSelectedDefaultSearchEngine(const TemplateURLData& data);
 
+  // Override the default search provider with an extension.
+  void SetExtensionControlledDefaultSearchEngine(const TemplateURLData& data);
+
+  // Clear the extension-provided default search engine. Does not explicitly
+  // disable Default Search. The new current default search engine will be
+  // defined by policy, extensions, or pre-populated data.
+  void ClearExtensionControlledDefaultSearchEngine();
+
   // Clear the user's default search provider choice from |pref_service_|. Does
   // not explicitly disable Default Search. The new default search
   // engine will be defined by policy, extensions, or pre-populated data.