Host fingerprint mojo service within the device service.

services/device/fingerprint/fingerprint_impl_default.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 SERVICES_DEVICE_FINGERPRINT_FINGERPRINT_IMPL_DEFAULT_H_
+#define SERVICES_DEVICE_FINGERPRINT_FINGERPRINT_IMPL_DEFAULT_H_
+
+#include "base/macros.h"
+#include "services/device/public/interfaces/fingerprint.mojom.h"
+
+namespace device {
+
+// An empty implementation of Fingerprint.
+// Used on platforms where a real implementation is not available.
+class FingerprintImplDefault : public mojom::Fingerprint {

[Rahul Chaturvedi, 2017/02/06 21:31:57]

Is this class strictly necessary? Can we instead just an empty definition of
class Fingerprint?

[xiaoyinh(OOO Sep 11-29), 2017/02/22 00:04:50]

Done.

+ public:
+  explicit FingerprintImplDefault();
+  ~FingerprintImplDefault() override;
+
+  // mojom::Fingerprint:
+  void GetFingerprintsList(
+      const GetFingerprintsListCallback& callback) override;
+  void StartEnroll(const std::string& user_id,
+                   const std::string& label) override;
+  void CancelCurrentEnroll() override;
+  void GetLabel(int32_t index, const GetLabelCallback& callback) override;
+  void SetLabel(const std::string& label, int32_t index) override;
+  void RemoveEnrollment(int32_t index) override;
+  void StartAuthentication() override;
+  void EndCurrentAuthentication() override;
+  void DestroyAllEnrollments() override;
+  void AddBiodObserver(mojom::BiodObserverPtr observer) override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(FingerprintImplDefault);
+};
+
+}  // namespace device
+
+#endif  // SERVICES_DEVICE_FINGERPRINT_FINGERPRINT_IMPL_DEFAULT_H_