Host fingerprint mojo service within the device service.

device/fingerprint/public/interfaces/fingerprint.mojom

Index: device/fingerprint/public/interfaces/fingerprint.mojom
diff --git a/device/fingerprint/public/interfaces/fingerprint.mojom b/device/fingerprint/public/interfaces/fingerprint.mojom
new file mode 100644
index 0000000000000000000000000000000000000000..3180f9c0026c77dba7bfebf3fe6f40cdb591d027
--- /dev/null
+++ b/device/fingerprint/public/interfaces/fingerprint.mojom
@@ -0,0 +1,26 @@
+// 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.
+
+module device.mojom;
+
+interface BiodObserver{
+  OnRestarted();
+  OnScanned(uint32 scan_result, bool is_complete);

[Tom Sepez, 2017/02/01 16:30:17]

is scan_result really a uint32, or some sort of enum?  

[xiaoyinh(OOO Sep 11-29), 2017/02/02 23:25:59]

Thanks for your comment.

You're right, scan_result is a enum and it will be defined in
third_party/cros_system_api/dbus/service_constants.h along with other
fingerprint related constants.

I can keep a copy of the enum here if that's desired.

+  OnAttempt(uint32 scan_result, array<string> recognized_user_ids);
+  OnFailure();
+};
+
+interface Fingerprint {
+  GetFingerprintsList() => (array<string> enrollments);

[Tom Sepez, 2017/02/01 16:30:17]

Is this a privileged interface?  Which clients do you expect to call this?  Are
the callers more trusted than the service itself?

[xiaoyinh(OOO Sep 11-29), 2017/02/02 23:25:59]

I think right now only md-settings and lock screen will call this. And they are
inside the chrome process, so I assume they are more trusted than the service
itself. Let me know if you think otherwise.

+  StartEnroll(string user_id, string label);
+  CancelCurrentEnroll();
+  GetLabel(int32 index) => (string label);
+  SetLabel(string label, int32 index);
+  RemoveEnrollment(int32 index);
+  StartAuthentication();
+  EndCurrentAuthentication();
+  DestroyAllEnrollments();
+  AddBiodObserver(BiodObserver observer);
+};
+