Move ranker_model_loader to a new component.

components/machine_intelligence/ranker_model_loader.h

 // Copyright 2017 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_RANKER_MODEL_LOADER_H_
-#define COMPONENTS_TRANSLATE_CORE_BROWSER_RANKER_MODEL_LOADER_H_
+#ifndef COMPONENTS_MACHINE_INTELLIGENCE_RANKER_MODEL_LOADER_H_
+#define COMPONENTS_MACHINE_INTELLIGENCE_RANKER_MODEL_LOADER_H_
 
 #include <memory>
 #include <string>
 
 #include "base/callback.h"
 #include "base/files/file_path.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/sequence_checker.h"
 #include "base/time/time.h"
+#include "net/url_request/url_request_context_getter.h"
 #include "url/gurl.h"
 
 namespace base {
 class SequencedTaskRunner;
 }  // namespace base
 
-namespace chrome_intelligence {
+namespace machine_intelligence {
+
+class RankerURLFetcher;
 class RankerModel;
-}  // namespace chrome_intelligence
-
-namespace translate {
-
-class TranslateURLFetcher;
 
 // Enumeration denoting the outcome of an attempt to download the model. This
 // must be kept in sync with the RankerModelStatus enum in histograms.xml
 enum class RankerModelStatus {
   OK = 0,
   DOWNLOAD_THROTTLED = 1,
   DOWNLOAD_FAILED = 2,
   PARSE_FAILED = 3,
   VALIDATION_FAILED = 4,
   INCOMPATIBLE = 5,
   LOAD_FROM_CACHE_FAILED = 6,
   MODEL_LOADING_ABANDONED = 7,
 
   // Insert new values above this line.
   MAX
 };
 
-// If enabled, downloads a translate ranker model and uses it to determine
-// whether the user should be given a translation prompt or not.
+// Loads a ranker model. Will attempt to load the model from disk cache. If it
+// fails, will attempt to download from the given URL.
 class RankerModelLoader {
  public:
   // Callback to validate a ranker model on behalf of the model loader client.
   // For example, the callback might validate that the model is compatible with
   // the features generated when ranking translation offerings.  This will be
   // called on the sequence on which the model loader was constructed.
   using ValidateModelCallback = base::RepeatingCallback<RankerModelStatus(
-      const chrome_intelligence::RankerModel&)>;
+      const machine_intelligence::RankerModel&)>;
 
   // Called to transfer ownership of a loaded model back to the model loader
   // client. This will be called on the sequence on which the model loader was
   // constructed.
   using OnModelAvailableCallback = base::RepeatingCallback<void(
-      std::unique_ptr<chrome_intelligence::RankerModel>)>;
+      std::unique_ptr<machine_intelligence::RankerModel>)>;
 
   // |validate_model_callback| may be called on any sequence; it must be thread
   // safe.
   //
   // |on_model_available_callback| will be called on the sequence on which the
   // ranker model loader is constructed.
   //
   // |model_path| denotes the file path at which the model is cached. The loader
   // will attempt to load the model from this path first, falling back to the
   // |model_url| if the model cannot be loaded or has expired. Upon downloading
   // a fresh model from |model_url| the model will be persisted to |model_path|
   // for subsequent caching.
   //
   // |model_url| denotes the URL from which the model should be loaded, if it
   // has not already been cached at |model_path|.
   //
   // |uma_prefix| will be used as a prefix for the names of all UMA metrics
   // generated by this loader.
   RankerModelLoader(ValidateModelCallback validate_model_callback,
                     OnModelAvailableCallback on_model_available_callback,
+                    net::URLRequestContextGetter* request_context_getter,
                     base::FilePath model_path,
                     GURL model_url,
                     std::string uma_prefix);
 
   ~RankerModelLoader();
 
   // Call this method periodically to notify the model loader the ranker is
   // actively in use. The user's engagement with the ranked feature is used
   // as a proxy for network availability and activity. If a model download
   // is pending, this will trigger (subject to retry and frequency limits) a
@@ skipping 30 matching lines @@
 
   // Called when the background worker has finished loading |data| from
   // |model_path_|. If |data| is empty, the load from |model_path_| failed.
   void OnFileLoaded(const std::string& data);
 
   // Asynchronously initiates loading the model from |model_url_|.
   void StartLoadFromURL();
 
   // Called when |url_fetcher_| has finished loading |data| from |model_url_|.
   //
-  // This call signature is mandated by TranslateURLFetcher.
+  // This call signature is mandated by RankerURLFetcher.
   //
-  // id - the id given to the TranslateURLFetcher on creation
   // success - true of the download was successful
   // data - the body of the downloads response
-  void OnURLFetched(int id, bool success, const std::string& data);
+  void OnURLFetched(bool success, const std::string& data);
 
   // Parse |data| and return a validated model. Returns nullptr on failure.
-  std::unique_ptr<chrome_intelligence::RankerModel> CreateAndValidateModel(
+  std::unique_ptr<machine_intelligence::RankerModel> CreateAndValidateModel(
       const std::string& data);
 
   // Helper function to log |model_status| to UMA and return it.
   RankerModelStatus ReportModelStatus(RankerModelStatus model_status);
 
   // Validates that ranker model loader tasks are all performed on the same
   // sequence.
-  base::SequenceChecker sequence_checker_;
+  SEQUENCE_CHECKER(sequence_checker_);
 
   // The task runner on which background tasks are performed.
   const scoped_refptr<base::SequencedTaskRunner> background_task_runner_;
 
   // Validates a ranker model on behalf of the model loader client. This will be
   // called on the sequence on which the model leader was constructed.
   const ValidateModelCallback validate_model_cb_;
 
   // Transfers ownership of a loaded model back to the model loader client.
   // This will be called on the sequence on which the model loader was
   // constructed.
   const OnModelAvailableCallback on_model_available_cb_;
 
+  // Request Context Getter used for RankerURLFetcher.
+  scoped_refptr<net::URLRequestContextGetter> request_context_getter_;
+
   // The path at which the model is (or should be) cached.
   const base::FilePath model_path_;
 
   // The URL from which to download the model if the model is not in the cache
   // or the cached model is invalid/expired.
   const GURL model_url_;
 
   // This will prefix all UMA metrics generated by the model loader.
   const std::string uma_prefix_;
 
   // Used to download model data from |model_url_|.
-  std::unique_ptr<TranslateURLFetcher> url_fetcher_;
+  std::unique_ptr<RankerURLFetcher> url_fetcher_;
 
   // The next time before which no new attempts to download the model should be
   // attempted.
   base::TimeTicks next_earliest_download_time_;
 
   // Tracks the last time of the last attempt to load a model, either from file
   // of from URL. Used for UMA reporting of load durations.
   base::TimeTicks load_start_time_;
 
   // The current state of the loader.
   LoaderState state_ = LoaderState::NOT_STARTED;
 
   // Creates weak pointer references to the loader.
   base::WeakPtrFactory<RankerModelLoader> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RankerModelLoader);
 };
 
-}  // namespace translate
+}  // namespace machine_intelligence
 
-#endif  // COMPONENTS_TRANSLATE_CORE_BROWSER_RANKER_MODEL_LOADER_H_
+#endif  // COMPONENTS_MACHINE_INTELLIGENCE_RANKER_MODEL_LOADER_H_