Allow AppSearchProvider to provide recommendations.

ui/app_list/search_provider.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 "ui/app_list/search_provider.h"
 
 #include "ui/app_list/search_result.h"
 
 namespace app_list {
 
 SearchProvider::SearchProvider() {
 }
+
 SearchProvider::~SearchProvider() {
 }
 
+void SearchProvider::FetchRecommendations() {
+  ClearResults();
+}
+
 void SearchProvider::ReleaseResult(std::vector<SearchResult*>* results) {
   results_.release(results);
 }
 
 void SearchProvider::Add(scoped_ptr<SearchResult> result) {
   results_.push_back(result.release());
   FireResultChanged();
 }
 
 void SearchProvider::ClearResults() {
   results_.clear();
   FireResultChanged();
 }
 
 void SearchProvider::FireResultChanged() {
   if (result_changed_callback_.is_null())
     return;
 
   result_changed_callback_.Run();
 }
 
 }  // namespace app_list