Change NTPSnippetsBridge to read from ContentSuggestionsService

components/ntp_snippets/content_suggestions_service.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 "components/ntp_snippets/content_suggestions_service.h"
 
 #include <algorithm>
 #include <iterator>
 
 #include "base/bind.h"
@@ skipping 88 matching lines @@
 
   // Remove the suggestion locally.
   id_category_map_.erase(suggestion_id);
   std::vector<ContentSuggestion>* suggestions =
       &suggestions_by_category_[category];
   auto position =
       std::find_if(suggestions->begin(), suggestions->end(),
                    [&suggestion_id](const ContentSuggestion& suggestion) {
                      return suggestion_id == suggestion.id();
                    });
-  DCHECK(position != suggestions->end());
+  DCHECK(position != suggestions->end())
+      << "The discarded suggestion " << suggestion_id
+      << " has already been removed. Providers must not call OnNewSuggestions"
+         " in response to DiscardSuggestion.";
   suggestions->erase(position);
 }
 
 void ContentSuggestionsService::AddObserver(Observer* observer) {
   observers_.AddObserver(observer);
 }
 
 void ContentSuggestionsService::RemoveObserver(Observer* observer) {
   observers_.RemoveObserver(observer);
 }
@@ skipping 78 matching lines @@
 }
 
 void ContentSuggestionsService::NotifyCategoryStatusChanged(
     ContentSuggestionsCategory category) {
   FOR_EACH_OBSERVER(
       Observer, observers_,
       OnCategoryStatusChanged(category, GetCategoryStatus(category)));
 }
 
 }  // namespace ntp_snippets