Revert of Support server categories in NTPSnippetsService. (patchset #3...

Revert of Support server categories in NTPSnippetsService. (patchset #3 id:40001 of https://codereview.chromium.org/2279863002/ )

Reason for revert:
I'm afraid this failed again on
https://build.chromium.org/p/chromium.mac/builders/Mac10.9%20Tests/builds/27385/steps/components_unittests%20on%20Mac-10.9

Original issue's description:
> Support server categories in NTPSnippetsService.
>
> Reland of:
> https://crrev.com/330958ddcdcd0084d724571eddaa66f9c364115f
>
> Not clear why tests failed; they passed for me and in the CQ.
> Removed one synchronization bit that wasn't really part of the change.
>
> BUG=633613
>
> Committed: https://crrev.com/880bb766ee4985a8dd36be10098c5196c41f7509
> Cr-Commit-Position: refs/heads/master@{#414681}

TBR=treib@chromium.org,sfiera@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=633613

Review-Url: https://codereview.chromium.org/2283743002
Cr-Commit-Position: refs/heads/master@{#414686}

components/ntp_snippets/ntp_snippets_fetcher.cc

@@ -651,7 +651,6 @@ void NTPSnippetsFetcher::FetchFinished(OptionalSnippets snippets,
                             static_cast<int>(result),
                             static_cast<int>(FetchResult::RESULT_MAX));
 
-  DVLOG(1) << "Fetch finished: " << last_status_;
   if (!snippets_available_callback_.is_null())
     snippets_available_callback_.Run(std::move(snippets));
 }

components/ntp_snippets/ntp_snippets_service.h

@@ -153,8 +153,8 @@ class NTPSnippetsService : public ContentSuggestionsProvider,
   static int GetMaxSnippetCountForTesting();
 
   // Available snippets, only for unit tests.
-  const NTPSnippet::PtrVector& GetSnippetsForTesting(Category category) const {
-    return categories_.find(category)->second.snippets;
+  const NTPSnippet::PtrVector& GetSnippetsForTesting() const {
+    return snippets_;
   }
 
  private:
@@ -222,7 +222,7 @@ class NTPSnippetsService : public ContentSuggestionsProvider,
   void OnFetchFinished(NTPSnippetsFetcher::OptionalSnippets snippets);
 
   // Merges newly available snippets with the previously available list.
-  void MergeSnippets(Category category, NTPSnippet::PtrVector new_snippets);
+  void MergeSnippets(NTPSnippet::PtrVector new_snippets);
 
   std::set<std::string> GetSnippetHostsFromPrefs() const;
   void StoreSnippetHostsToPrefs(const std::set<std::string>& hosts);
@@ -239,18 +239,18 @@ class NTPSnippetsService : public ContentSuggestionsProvider,
   void FinishInitialization();
 
   void OnSnippetImageFetchedFromDatabase(const ImageFetchedCallback& callback,
-                                         const std::string& suggestion_id,
+                                         const std::string& snippet_id,
                                          std::string data);
 
   void OnSnippetImageDecodedFromDatabase(const ImageFetchedCallback& callback,
-                                         const std::string& suggestion_id,
+                                         const std::string& snippet_id,
                                          const gfx::Image& image);
 
-  void FetchSnippetImageFromNetwork(const std::string& suggestion_id,
+  void FetchSnippetImageFromNetwork(const std::string& snippet_id,
                                     const ImageFetchedCallback& callback);
 
   void OnSnippetImageDecodedFromNetwork(const ImageFetchedCallback& callback,
-                                        const std::string& suggestion_id,
+                                        const std::string& snippet_id,
                                         const gfx::Image& image);
 
   // Triggers a state transition depending on the provided reason to be
@@ -261,7 +261,7 @@ class NTPSnippetsService : public ContentSuggestionsProvider,
   // Verifies state transitions (see |State|'s documentation) and applies them.
   // Also updates the provider status. Does nothing except updating the provider
   // status if called with the current state.
-  void EnterState(State state);
+  void EnterState(State state, CategoryStatus status);
 
   // Enables the service and triggers a fetch if required. Do not call directly,
   // use |EnterState| instead.
@@ -278,42 +278,24 @@ class NTPSnippetsService : public ContentSuggestionsProvider,
   // the observers.
   void NotifyNewSuggestions();
 
-  // Updates the internal status for |category| to |category_status_| and
-  // notifies the content suggestions observer if it changed.
-  void UpdateCategoryStatus(Category category, CategoryStatus status);
-  // Calls UpdateCategoryStatus() for all provided categories.
-  void UpdateAllCategoryStatus(CategoryStatus status);
+  // Updates the internal status |category_status_| and notifies the content
+  // suggestions observer if it changed.
+  void UpdateCategoryStatus(CategoryStatus status);
 
   State state_;
 
+  CategoryStatus category_status_;
+
   PrefService* pref_service_;
 
   suggestions::SuggestionsService* suggestions_service_;
 
-  const Category articles_category_;
-
-  struct CategoryContent {
-    CategoryStatus status = CategoryStatus::INITIALIZING;
-
-    // True iff the server returned results in this category in the last fetch.
-    // We never remove categories that the server still provides, but if the
-    // server stops providing a category, we won't yet report it as NOT_PROVIDED
-    // while we still have non-expired snippets in it.
-    bool provided_by_server = true;
-
-    // All current suggestions (i.e. not dismissed ones).
-    NTPSnippet::PtrVector snippets;
+  // All current suggestions (i.e. not dismissed ones).
+  NTPSnippet::PtrVector snippets_;
 
-    // Suggestions that the user dismissed. We keep these around until they
-    // expire so we won't re-add them on the next fetch.
-    NTPSnippet::PtrVector dismissed;
-
-    CategoryContent();                              // = default, in .cc
-    CategoryContent(CategoryContent&&);             // = default, in .cc
-    ~CategoryContent();                             // = default, in .cc
-    CategoryContent& operator=(CategoryContent&&);  // = default, in .cc
-  };
-  std::map<Category, CategoryContent, Category::CompareByID> categories_;
+  // Suggestions that the user dismissed. We keep these around until they expire
+  // so we won't re-add them on the next fetch.
+  NTPSnippet::PtrVector dismissed_snippets_;
 
   // The ISO 639-1 code of the language used by the application.
   const std::string application_language_code_;
@@ -356,6 +338,8 @@ class NTPSnippetsService : public ContentSuggestionsProvider,
   // loaded. The nuke will be executed after the database load finishes.
   bool nuke_after_load_;
 
+  const Category provided_category_;
+
   // Request throttler for limiting requests to thumbnail images.
   RequestThrottler thumbnail_requests_throttler_;