UKM Sync Observer

components/ukm/observers/sync_disable_observer.h

Index: components/ukm/observers/sync_disable_observer.h
diff --git a/components/ukm/observers/sync_disable_observer.h b/components/ukm/observers/sync_disable_observer.h
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+++ b/components/ukm/observers/sync_disable_observer.h
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+// 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_OBSERVERS_SYNC_DISABLE_OBSERVER_H_
+#define COMPONENTS_UKM_OBSERVERS_SYNC_DISABLE_OBSERVER_H_
+
+#include <map>
+
+#include "base/scoped_observer.h"
+#include "components/sync/driver/sync_service.h"
+#include "components/sync/driver/sync_service_observer.h"
+
+namespace ukm {
+
+// Observes the state of a set of SyncServices for changes to history sync
+// preferences.  This is for used to trigger purging of local state when
+// sync is disabled on a profile and disabling recording when any non-syncing
+// profiles are active.
+class SyncDisableObserver : public syncer::SyncServiceObserver {
+ public:
+  SyncDisableObserver();
+  ~SyncDisableObserver() override;
+
+  // Helper method to check if history sync is enabled.
+  static bool IsHistorySyncEnabled(syncer::SyncService* sync_service);
+
+  // Starts observing a service for sync disables.
+  void ObserveServiceForSyncDisables(syncer::SyncService* sync_service);
+
+  // Returns if history sync is enabled on all active profiles.
+  virtual bool IsHistorySyncEnabledOnAllProfiles();
+
+ protected:
+  // Called after state changes and some profile has sync disabled.
+  // If |must_purge| is true, sync was disabled for some profile, and
+  // local data should be purged.
+  virtual void OnSyncPrefsChanged(bool must_purge) = 0;
+
+ private:
+  // syncer::SyncServiceObserver:
+  void OnSyncConfigurationCompleted(syncer::SyncService* sync) override;
+  void OnSyncShutdown(syncer::SyncService* sync) override;
+
+  // Recomputes all_profiles_enabled_ state from was_enabled_map_;
+  void UpdateAllProfileEnabled(bool must_purge);
+
+  // Tracks observed history services, for cleanup.
+  ScopedObserver<syncer::SyncService, syncer::SyncServiceObserver>
+      sync_observer_;
+
+  // The list of services that had sync enabled when we last checked.
+  std::map<syncer::SyncService*, bool> was_enabled_map_;
+
+  // Tracks if sync was enabled on all profiles after the last state change.
+  bool all_profiles_enabled_;
+
+  DISALLOW_COPY_AND_ASSIGN(SyncDisableObserver);
+};
+
+}  // namespace ukm
+
+#endif  // COMPONENTS_UKM_OBSERVERS_SYNC_DISABLE_OBSERVER_H_