[NTP::PhysicalWeb] Implement suggestion dismissal.

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 <set>
 #include <utility>
@@ skipping 150 matching lines @@
     const ContentSuggestion::ID& suggestion_id) {
   if (!providers_by_category_.count(suggestion_id.category())) {
     LOG(WARNING) << "Dismissed suggestion " << suggestion_id
                  << " for unavailable category " << suggestion_id.category();
     return;
   }
   providers_by_category_[suggestion_id.category()]->DismissSuggestion(
       suggestion_id);
 
   // Remove the suggestion locally.
-  bool removed = RemoveSuggestionByID(suggestion_id);
-  DCHECK(removed) << "The dismissed suggestion " << suggestion_id
-                  << " has already been removed. Providers must not call"
-                  << " OnNewSuggestions in response to DismissSuggestion.";
+  RemoveSuggestionByID(suggestion_id);

[jkrcal, 2016/12/07 14:20:01]

Why did you remove the DCHECK?

[vitaliii, 2016/12/08 07:13:41]

Because of it one could not dismiss suggestions obtained through "More" action
(i.e. through |Fetch| call). Previously, the "More" action was used only for
articles and added suggestions were propagated to new NTPs through
OnNewSuggestions, so this DCHECK did not fire. However, in Physical Web provider
the suggestions are not propagated to new NTPs and this DCHECK fires.

[jkrcal, 2016/12/08 09:55:42]

Ok, please expand the comment.

[vitaliii, 2016/12/08 11:05:29]

Done.

 }
 
 void ContentSuggestionsService::DismissCategory(Category category) {
   auto providers_it = providers_by_category_.find(category);
   if (providers_it == providers_by_category_.end()) {
     return;
   }
 
   ContentSuggestionsProvider* provider = providers_it->second;
   UnregisterCategory(category, provider);
@@ skipping 310 matching lines @@
 void ContentSuggestionsService::StoreDismissedCategoriesToPrefs() {
   base::ListValue list;
   for (const auto& category_provider_pair : dismissed_providers_by_category_) {
     list.AppendInteger(category_provider_pair.first.id());
   }
 
   pref_service_->Set(prefs::kDismissedCategories, list);
 }
 
 }  // namespace ntp_snippets