Make extensions DSE persistent in browser prefs

components/search_engines/template_url_service_client.h

 // Copyright 2014 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.
 
 #ifndef COMPONENTS_SEARCH_ENGINES_TEMPLATE_URL_SERVICE_CLIENT_H_
 #define COMPONENTS_SEARCH_ENGINES_TEMPLATE_URL_SERVICE_CLIENT_H_
 
 #include "base/strings/string16.h"
 #include "components/search_engines/template_url_id.h"
 
@@ skipping 22 matching lines @@
   virtual void SetKeywordSearchTermsForURL(const GURL& url,
                                            TemplateURLID id,
                                            const base::string16& term) = 0;
 
   // Adds the given URL to history as a keyword generated visit.
   virtual void AddKeywordGeneratedVisit(const GURL& url) = 0;
 
   // Given the main search |url| for a TemplateURL, returns whether the
   // TemplateURL is from an omnibox extension.
   virtual bool IsOmniboxExtensionURL(const std::string& url) = 0;
+
+  // Returns extension id for extension that is currently overriding default
+  // search preference.
+  virtual std::string GetExtensionControllingDSEPref() = 0;

[vasilii, 2016/12/06 19:16:42]

Hopefully, you won't need it. The component should know better the current
state. 

[Alexander Yashkin, 2016/12/09 08:19:52]

I have written my thoughts above, not sure we can get without it.

 };
 
 #endif  // COMPONENTS_SEARCH_ENGINES_TEMPLATE_URL_SERVICE_CLIENT_H_