cros: DBUS client to interact with fingerprint DBUS API.

chromeos/dbus/biod_biometrics_manager_client.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 CHROMEOS_DBUS_BIOD_BIOMETRICS_MANAGER_CLIENT_H_
+#define CHROMEOS_DBUS_BIOD_BIOMETRICS_MANAGER_CLIENT_H_
+
+#include <stdint.h>
+
+#include <unordered_map>
+#include <vector>
+
+#include "base/callback.h"
+#include "base/macros.h"
+#include "base/observer_list.h"
+#include "chromeos/chromeos_export.h"
+#include "chromeos/dbus/dbus_client.h"
+#include "chromeos/dbus/dbus_client_implementation_type.h"
+#include "chromeos/dbus/dbus_method_call_status.h"
+#include "third_party/cros_system_api/dbus/service_constants.h"
+
+namespace chromeos {
+
+// Each time the sensor detects a scan, an object containing all the users, each
+// with the labels of all the matched stored fingerprints is returned.
+using AuthScanMatches =
+    std::unordered_map<std::string, std::vector<std::string>>;
+
+// BiodBiometricsManagerClient is used to communicate with the biod dbus
+// interface.
+class CHROMEOS_EXPORT BiodBiometricsManagerClient : public DBusClient {
+ public:
+  // Interface for observing changes from the biometrics.
+  class Observer {
+   public:
+    // Called when biometrics manager powers up or is restarted.
+    virtual void ClientRestarted() {}
+
+    // Called whenever a user attempts a scan. |scan_result| tells whether the
+    // scan was succesful. |is_complete| tells whether enrollment is complete
+    // and now over.
+    virtual void EnrollScanDoneReceived(uint32_t scan_result,

[stevenjb, 2017/03/21 18:46:16]

EnrollScanCompleteReceived ?

[sammiequon, 2017/03/21 20:50:19]

These signals are based of the dbus signal names found here
https://cs.corp.google.com/clankium/src/third_party/cros_system_api/dbus/serv....

There was a long discussion and the folks writing the daemon settled on these
names.

+                                        bool is_complete) {}
+
+    // Called to indicate a bad scan of any kind, or a succesful scan. If scan
+    // is successful, |matches| will equal all the enrollment IDs that match the
+    // scan, and the labels of the matched fingeprints.
+    virtual void AuthScanDoneReceived(uint32_t scan_result,

[stevenjb, 2017/03/21 18:46:16]

Complete?

[sammiequon, 2017/03/21 20:50:18]

See above.

+                                      const AuthScanMatches& matches) {}
+
+    // Called during either mode to indicate a failure. Any enrollment that was
+    // underway is thrown away and authentication will no longer be happening.
+    virtual void ScanFailedReceived() {}
+
+   protected:
+    virtual ~Observer() {}
+  };
+
+  ~BiodBiometricsManagerClient() override;
+
+  // Adds and removes the observer.
+  virtual void AddObserver(Observer* observer) = 0;
+  virtual void RemoveObserver(Observer* observer) = 0;

[stevenjb, 2017/03/21 18:46:16]

nit: blank line here

[sammiequon, 2017/03/21 20:50:19]

Done.

+  // Returns true if this object has the given observer.
+  virtual bool HasObserver(const Observer* observer) const = 0;
+
+  // ObjectPathArrayCallback is used for the GetRecordsForUser method. It
+  // receives one argument which contains a list of the stored records object
+  // paths for a given user.

[stevenjb, 2017/03/21 18:46:17]

We should either name this type more specifically (e.g. UserRecordsCallback), or
move the bulk of this comment to where it is used. Currently it's unclear
looking at GetRecordsForUser what the callback contains since it looks like a
generic callbakc type.

[sammiequon, 2017/03/21 20:50:18]

Done.

+  using ObjectPathArrayCallback =
+      base::Callback<void(const std::vector<dbus::ObjectPath>&)>;
+
+  // BiometricTypeCallback is used for the GetType method. It receives
+  // one argument which states the type of biometric.
+  using BiometricTypeCallback = base::Callback<void(biod::BiometricType)>;
+
+  // Starts the biometric enroll session.

[stevenjb, 2017/03/21 18:46:17]

Describe what is passed to |callback|.

[sammiequon, 2017/03/21 20:50:19]

Done.

+  virtual void StartEnrollSession(const std::string& user_id,
+                                  const std::string& label,
+                                  const ObjectPathCallback& callback) = 0;
+
+  // Gets all the records registered with this biometric.

[stevenjb, 2017/03/21 18:46:16]

See above

[sammiequon, 2017/03/21 20:50:19]

Done.

+  virtual void GetRecordsForUser(const std::string& user_id,
+                                 const ObjectPathArrayCallback& callback) = 0;
+
+  // Irreversibly destroys all records registered with this biometric.
+  virtual void DestroyAllRecords() = 0;
+
+  // Starts the biometric authentication session.

[stevenjb, 2017/03/21 18:46:16]

What gets passed to |calback|?

[sammiequon, 2017/03/21 20:50:19]

Done.

+  virtual void StartAuthSession(const ObjectPathCallback& callback) = 0;
+
+  // Gets the type of biometric.

[stevenjb, 2017/03/21 18:46:16]

nit: s/gets/requests/

[sammiequon, 2017/03/21 20:50:19]

Done.

+  virtual void GetType(const BiometricTypeCallback& callback) = 0;
+
+  // Same as above but is synchronous.
+  virtual biod::BiometricType GetTypeBlocking() = 0;

[stevenjb, 2017/03/21 18:46:16]

We should avoid using blocking dbus calls like this pretty much always.

[sammiequon, 2017/03/21 20:50:18]

Done.

+
+  // Creates the instance.
+  static BiodBiometricsManagerClient* Create(DBusClientImplementationType type);
+
+ protected:
+  friend class BiodBiometricsManagerClientTest;
+
+  // Create() should be used instead.
+  BiodBiometricsManagerClient();
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(BiodBiometricsManagerClient);
+};
+
+}  // namespace chromeos
+
+#endif  // CHROMEOS_DBUS_BIOD_BIOMETRICS_MANAGER_CLIENT_H_