[SuggestionsService] Split SuggestionsService interface from impl

chrome/browser/search/suggestions/suggestions_ui.cc

 // Copyright 2016 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 "chrome/browser/search/suggestions/suggestions_ui.h"
 
 #include <map>
 #include <string>
 
 #include "base/barrier_closure.h"
@@ skipping 182 matching lines @@
   if (!suggestions_service) {
     std::string output = RenderOutputHtmlNoSuggestions(is_refresh);
     callback.Run(base::RefCountedString::TakeString(&output));
     return;
   }
 
   if (is_refresh)
     suggestions_service->FetchSuggestionsData();
 
   SuggestionsProfile suggestions_profile =
-      suggestions_service->GetSuggestionsDataFromCache();
+      suggestions_service->GetSuggestionsDataFromCache().value_or(
+          SuggestionsProfile());
   size_t size = suggestions_profile.suggestions_size();
   if (!size) {
     std::string output = RenderOutputHtmlNoSuggestions(is_refresh);
     callback.Run(base::RefCountedString::TakeString(&output));
   } else {
     RequestContext* context =
         new RequestContext(is_refresh, suggestions_profile, callback);
     base::Closure barrier = BarrierClosure(
         size, base::Bind(&SuggestionsSource::OnThumbnailsFetched,
                          weak_ptr_factory_.GetWeakPtr(), context));
@@ skipping 48 matching lines @@
 
 SuggestionsUI::SuggestionsUI(content::WebUI* web_ui)
     : content::WebUIController(web_ui) {
   Profile* profile = Profile::FromWebUI(web_ui);
   content::URLDataSource::Add(profile, new SuggestionsSource(profile));
 }
 
 SuggestionsUI::~SuggestionsUI() {}
 
 }  // namespace suggestions