Revert "[translate] Add translate ranker model loader."

components/translate/core/browser/translate_ranker.h

 // 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.
 
 #ifndef COMPONENTS_TRANSLATE_CORE_BROWSER_TRANSLATE_RANKER_H_
 #define COMPONENTS_TRANSLATE_CORE_BROWSER_TRANSLATE_RANKER_H_
 
 #include <memory>
 #include <string>
-#include <vector>
 
-#include "base/macros.h"
-#include "components/keyed_service/core/keyed_service.h"
+#include "base/feature_list.h"
+#include "base/gtest_prod_util.h"
+#include "base/memory/singleton.h"
+
+namespace chrome_intelligence {
+class TranslateRankerModel;
+}
 
 namespace metrics {
 class TranslateEventProto;
-}  // namespace metrics
+}
 
 namespace translate {
 
 class TranslatePrefs;
+class TranslateURLFetcher;
+
+// Features used to enable ranker query, enforcement and logging. Note that
+// enabling enforcement implies (forces) enabling queries.
+extern const base::Feature kTranslateRankerQuery;
+extern const base::Feature kTranslateRankerEnforcement;
+extern const base::Feature kTranslateRankerLogging;
 
 // If enabled, downloads a translate ranker model and uses it to determine
 // whether the user should be given a translation prompt or not.
-class TranslateRanker : public KeyedService {
+class TranslateRanker {
  public:
-  TranslateRanker() = default;
+  ~TranslateRanker();
+
+  // Returns true if query or enforcement is enabled.
+  static bool IsEnabled();
 
   // Returns true if translate events logging is enabled.
-  virtual bool IsLoggingEnabled() = 0;
+  static bool IsLoggingEnabled();
+
+  // Returns true if querying is enabled.
+  static bool IsQueryEnabled();
 
   // Returns true if enforcement is enabled.
-  virtual bool IsEnforcementEnabled() = 0;
+  static bool IsEnforcementEnabled();
 
-  // Returns true if querying is enabled.
-  virtual bool IsQueryEnabled() = 0;
+  // Returns the singleton TranslateRanker instance.
+  static TranslateRanker* GetInstance();
 
-  // Returns the version id for the ranker model.
-  virtual int GetModelVersion() const = 0;
+  // For testing only. Returns a TranslateRanker instance preloaded with a
+  // TranslateRankerModel as defined by |model_data|.
+  static std::unique_ptr<TranslateRanker> CreateForTesting(
+      const std::string& model_data);
+
+  // Initiates downloading of the assist model data. This is a NOP if the model
+  // data has already been downloaded.
+  void FetchModelData();
 
   // Returns true if executing the ranker model in the translation prompt
   // context described by |translate_prefs|, |src_lang|, |dst_lang| and possibly
   // other global browser context attributes suggests that the user should be
   // prompted as to whether translation should be performed.
-  virtual bool ShouldOfferTranslation(const TranslatePrefs& translate_prefs,
-                                      const std::string& src_lang,
-                                      const std::string& dst_lang) = 0;
+  bool ShouldOfferTranslation(const TranslatePrefs& translate_prefs,
+                              const std::string& src_lang,
+                              const std::string& dst_lang);
+
+  // Returns the model version (a date stamp) or 0 if there is no valid model.
+  int GetModelVersion() const;
 
   // Caches the translate event.
-  virtual void AddTranslateEvent(
-      const metrics::TranslateEventProto& translate_event) = 0;
+  void RecordTranslateEvent(
+      const metrics::TranslateEventProto& translate_event);
 
   // Transfers cached translate events to the given vector pointer and clears
   // the cache.
-  virtual void FlushTranslateEvents(
-      std::vector<metrics::TranslateEventProto>* events) = 0;
+  void FlushTranslateEvents(
+      std::vector<metrics::TranslateEventProto>* translate_events);
 
  private:
+  // The ID which is assigned to the underlying URLFetcher.
+  static constexpr int kFetcherId = 2;
+
+  TranslateRanker();
+
+  // Exposed for testing via FRIEND_TEST.
+  double CalculateScore(int accept_count,
+                        int decline_count,
+                        int ignore_count,
+                        const std::string& src_lang,
+                        const std::string& dst_lang,
+                        const std::string& app_locale,
+                        const std::string& country);
+
+  // Called when the model download has completed.
+  void ParseModel(int id, bool success, const std::string& model_data);
+
+  // The translation ranker model.
+  std::unique_ptr<chrome_intelligence::TranslateRankerModel> model_;
+
+  // A URL fetcher to download translation ranker model data.
+  std::unique_ptr<TranslateURLFetcher> model_fetcher_;
+
+  // The next time before which no new attempts to download the model should be
+  // attempted.
+  base::Time next_earliest_download_time_;
+
+  // Tracks the last time the translate ranker attempted to download its model.
+  // Used for UMA reporting of timing.
+  base::Time download_start_time_;
+
+  // Saved cache of translate event protos.
+  std::vector<metrics::TranslateEventProto> translate_events_cache_;
+
+  FRIEND_TEST_ALL_PREFIXES(TranslateRankerTest, CalculateScore);
+
+  friend struct base::DefaultSingletonTraits<TranslateRanker>;
+
   DISALLOW_COPY_AND_ASSIGN(TranslateRanker);
 };
 
 }  // namespace translate
 
 #endif  // COMPONENTS_TRANSLATE_CORE_BROWSER_TRANSLATE_RANKER_H_