Run RemoveArcData after a user has opted out

components/arc/user_data/arc_user_data_service.h

Index: components/arc/user_data/arc_user_data_service.h
diff --git a/components/arc/user_data/arc_user_data_service.h b/components/arc/user_data/arc_user_data_service.h
new file mode 100644
index 0000000000000000000000000000000000000000..9799077c67893f1f39043241355a277cf3eeece6
--- /dev/null
+++ b/components/arc/user_data/arc_user_data_service.h
@@ -0,0 +1,48 @@
+// 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_ARC_USER_DATA_ARC_USER_DATA_SERVICE
+#define COMPONENTS_ARC_USER_DATA_ARC_USER_DATA_SERVICE
+
+#include "base/macros.h"
+#include "base/threading/thread_checker.h"
+#include "components/arc/arc_bridge_service.h"
+#include "components/signin/core/account_id/account_id.h"
+
+class PrefService;
+
+namespace arc {
+
+class ArcServiceManager;
+class ArcBridgeService;
+
+// This class controls the lifecycle of ARC user data, removing it when
+// necessary.
+class ArcUserDataService : public ArcBridgeService::Observer {
+ public:
+  explicit ArcUserDataService(const ArcServiceManager* arc_service_manager);
+  ~ArcUserDataService() override;
+
+  // Checks if ARC is both stopped and disabled (not opt-in) and triggers
+  // removal of user data if both conditions are true.
+  void ClearIfDisabled(const AccountId& account_id);

[Daniel Erat, 2016/05/24 16:00:01]

i think that this would be clearer if it were named OnPrimaryUserProfilePrepared
or SetPrimaryUserAccountId or something similar. that way, it's obvious when
it's supposed to be called, and it makes more sense that it's setting
user_prefs_account_id_ (which should probably also be renamed to something like
primary_user_account_id_), and all the logic about what actually needs to be
done (i.e. clearing user data if arc is disabled) will be contained within this
class.

[dspaid, 2016/05/25 00:06:48]

Done.

+
+  // Called whenever the arc bridge is stopped to potentially remove data if

[Daniel Erat, 2016/05/24 16:00:01]

nit: s/arc/ARC/

also add a comment first describing where this method comes from, e.g.

// ArcBridgeService::Observer:

[dspaid, 2016/05/25 00:06:48]

Done.

+  // the user has not opted in.
+  void OnBridgeStopped() override;
+
+ private:
+  base::ThreadChecker thread_checker_;
+
+  // Account ID for the account for which we currently have opt-in information.
+  AccountId user_prefs_account_id_ = EmptyAccountId();
+
+  const ArcServiceManager* const arc_service_manager_;
+
+  DISALLOW_COPY_AND_ASSIGN(ArcUserDataService);
+};
+
+}  // namespace arc
+
+#endif  // COMPONENTS_ARC_USER_DATA_ARC_USER_DATA_SERVICE