Basic UkmService implementation

components/ukm/ukm_service.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_UKM_UKM_SERVICE_H_
+#define COMPONENTS_UKM_UKM_SERVICE_H_
+
+#include <stddef.h>
+
+#include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+#include "base/threading/thread_checker.h"
+#include "components/metrics/metrics_reporting_scheduler.h"
+#include "components/metrics/persisted_logs.h"
+
+class PrefRegistrySimple;
+class PrefService;
+
+namespace metrics {
+class MetricsLogUploader;
+class MetricsServiceClient;
+}
+
+namespace ukm {
+
+// Manages the generation and uploading of UKM reports.

[rkaplow, 2017/01/04 17:57:57]

I'd suggest a bit more top-level documentation on what this is about here

[Steven Holte, 2017/01/04 22:47:55]

Expanded this a bit.

+class UkmService : public base::SupportsWeakPtr<UkmService> {
+ public:
+  // Constructs a UkmService.
+  // Calling code is responsible for ensuring that the lifetime of
+  // |pref_service| is longer than the lifetime of UkmService.
+  UkmService(
+    PrefService* pref_service,
+    metrics::MetricsServiceClient* client);
+  virtual ~UkmService();
+
+  // Initializes the UKM service.
+  void Initialize();
+
+  // Enable/disable transmission of accumulated logs.  Logs that have already
+  // been created will remain persisted to disk.
+  void EnableReporting();
+  void DisableReporting();
+
+  // Registers the names of all of the preferences used by UkmService in
+  // the provided PrefRegistry.
+  static void RegisterPrefs(PrefRegistrySimple* registry);
+
+ private:
+  // Start metrics client initialization.
+  void StartInitTask();
+
+  // Called when initialization tasks are complete, to notify the scheduler
+  // that it can begin calling RotateLog.
+  void FinishedInitTask();
+
+  // Periodically called by scheduler_ to advance processing of logs.
+  void RotateLog();
+
+  // Constructs a new Report from available data and stores it in
+  // persisted_logs_.
+  void BuildAndStoreLog();
+
+  // Start an upload of the next log from persisted_logs_.
+  void StartScheduledUpload();
+
+  // Called by log_uploader_ when the an upload is completed.
+  void OnLogUploadComplete(int response_code);
+
+  // A weak pointer to the PrefService used to read and write preferences.
+  PrefService* pref_service_;
+
+  // The UKM client id stored in prefs.
+  uint64_t client_id_;
+
+  // Used to interact with the embedder. Weak pointer; must outlive |this|
+  // instance.
+  metrics::MetricsServiceClient* const client_;
+
+  // Logs that have not yet been sent.
+  metrics::PersistedLogs persisted_logs_;
+
+  // The scheduler for determining when uploads should happen.
+  std::unique_ptr<metrics::MetricsReportingScheduler> scheduler_;
+
+  base::ThreadChecker thread_checker_;
+
+  // Instance of the helper class for uploading logs.
+  std::unique_ptr<metrics::MetricsLogUploader> log_uploader_;
+
+  bool initialize_started_;
+  bool log_upload_in_progress_;
+
+  // Weak pointers factory used to post task on different threads. All weak
+  // pointers managed by this factory have the same lifetime as UkmService.
+  base::WeakPtrFactory<UkmService> self_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(UkmService);
+};
+
+}  // namespace ukm
+
+#endif  // COMPONENTS_UKM_UKM_SERVICE_H_