Allow AppSearchProvider to provide recommendations.

ui/app_list/search_provider.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 UI_APP_LIST_SEARCH_PROVIDER_H_
 #define UI_APP_LIST_SEARCH_PROVIDER_H_
 
 #include "base/basictypes.h"
 #include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/scoped_vector.h"
 #include "base/strings/string16.h"
 #include "ui/app_list/app_list_export.h"
 
 namespace app_list {
 
 class SearchResult;
 
 class APP_LIST_EXPORT SearchProvider {
  public:
   typedef ScopedVector<SearchResult> Results;
   typedef base::Closure ResultChangedCallback;
 
   SearchProvider();
   virtual ~SearchProvider();
 
-  // Invoked to start a query.
+  // Invoked to start a query for recommendations.
+  virtual void FetchRecommendations();

[Matt Giuca, 2014/07/22 04:31:08]

I'm wondering if it's simpler to just make Start("") fetch recommendations. It
would eliminate a lot of methods and a little bit of code. It looks like the two
operations are more similar than different, but maybe you object.

[calamity, 2014/07/22 07:24:04]

I agree. I walked in thinking this would be cleaner but looking now, it seems
unnecessary.

+
+  // Invoked to start a query for a search term.
   virtual void Start(const base::string16& query) = 0;
 
   // Invoked to stop the current query and no more results changes.
   virtual void Stop() = 0;
 
   void set_result_changed_callback(const ResultChangedCallback& callback) {
     result_changed_callback_ = callback;
   }
 
   // TODO(mukai): Fix the ownership and copying of the results.
@@ skipping 11 matching lines @@
 
   ResultChangedCallback result_changed_callback_;
   Results results_;
 
   DISALLOW_COPY_AND_ASSIGN(SearchProvider);
 };
 
 }  // namespace app_list
 
 #endif  // UI_APP_LIST_SEARCH_PROVIDER_H_