[Android] Allow setting recently visited search engines as default search engine

components/search_engines/template_url_service.cc

 // 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.
 
 #include "components/search_engines/template_url_service.h"
 
 #include <algorithm>
 #include <utility>
 
 #include "base/auto_reset.h"
@@ skipping 395 matching lines @@
 
 void TemplateURLService::AddMatchingDomainKeywords(
     const base::string16& prefix,
     bool supports_replacement_only,
     TURLsAndMeaningfulLengths* matches) {
   AddMatchingKeywordsHelper(
       keyword_domain_to_turl_and_length_, prefix, supports_replacement_only,
       matches);
 }
 
+bool TemplateURLService::IsInDefaultList(const TemplateURL* t_url) {
+  return t_url->prepopulate_id() > 0 || t_url->created_by_policy();
+}
+
 TemplateURL* TemplateURLService::GetTemplateURLForKeyword(
     const base::string16& keyword) {
   KeywordToTURLAndMeaningfulLength::const_iterator elem(
       keyword_to_turl_and_length_.find(keyword));
   if (elem != keyword_to_turl_and_length_.end())
     return elem->second.first;
   return (!loaded_ && initial_default_search_provider_ &&
           (initial_default_search_provider_->keyword() == keyword))
              ? initial_default_search_provider_.get()
              : nullptr;
@@ skipping 1209 matching lines @@
   if (!urls)
     return true;
   for (TemplateURLSet::const_iterator i(urls->begin()); i != urls->end(); ++i) {
     if (!(*i)->safe_for_autoreplace())
       return false;
   }
   return true;
 }
 
 bool TemplateURLService::CanReplace(const TemplateURL* t_url) {
-  return (t_url != default_search_provider_ && !t_url->show_in_default_list() &&
+  return (t_url != default_search_provider_ && !IsInDefaultList(t_url) &&
           t_url->safe_for_autoreplace());
 }
 
 TemplateURL* TemplateURLService::FindNonExtensionTemplateURLForKeyword(
     const base::string16& keyword) {
   TemplateURL* keyword_turl = GetTemplateURLForKeyword(keyword);
   if (!keyword_turl || (keyword_turl->type() == TemplateURL::NORMAL))
     return keyword_turl;
   // The extension keyword in the model may be hiding a replaceable
   // non-extension keyword.  Look for it.
@@ skipping 818 matching lines @@
 
   if (most_recently_intalled_default) {
     base::AutoReset<DefaultSearchChangeOrigin> change_origin(
         &dsp_change_origin_, DSP_CHANGE_OVERRIDE_SETTINGS_EXTENSION);
     default_search_manager_.SetExtensionControlledDefaultSearchEngine(
         most_recently_intalled_default->data());
   } else {
     default_search_manager_.ClearExtensionControlledDefaultSearchEngine();
   }
 }