Make extensions DSE persistent in browser prefs (Reland)

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 aadc6a4648952a740881931ea7ac2c7fed629882..f5e85fdb53b3f30cbdee813dc39285e707b4e973 100644
--- a/components/search_engines/default_search_manager.h
+++ b/components/search_engines/default_search_manager.h
@@ -62,6 +62,8 @@ class DefaultSearchManager {
   static const char kCreatedByPolicy[];
   static const char kDisabledByPolicy[];
 
+  static const char kExtensionID[];
+
   enum Source {
     FROM_FALLBACK = 0,
     FROM_USER,
@@ -99,14 +101,6 @@ class DefaultSearchManager {
   // 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.