bluetooth: Add basic scanning to chrome://bluetooth-internals.

device/bluetooth/discovery_session.h

Index: device/bluetooth/discovery_session.h
diff --git a/device/bluetooth/discovery_session.h b/device/bluetooth/discovery_session.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 DEVICE_BLUETOOTH_DISCOVERY_SESSION_H_
+#define DEVICE_BLUETOOTH_DISCOVERY_SESSION_H_
+
+#include "base/memory/ptr_util.h"
+#include "device/bluetooth/bluetooth_discovery_session.h"
+#include "device/bluetooth/public/interfaces/adapter.mojom.h"
+
+namespace bluetooth {
+
+// Implementation of Mojo DiscoverySession in
+// device/bluetooth/public/interfaces/adapter.mojom.
+// It handles requests to interact with a DiscoverySession.
+// Uses the platform abstraction of device/bluetooth.
+// An instance of this class is constructed by Adapter and strongly bound
+// to its MessagePipe. When the instance is destroyed, the underlying
+// BluetoothDiscoverySession is requested to stop. Users are encouraged to call
+// DiscoverySession::Stop in order to respond to a failed request to stop
+// device discovery.
+class DiscoverySession : public mojom::DiscoverySession {
+ public:
+  explicit DiscoverySession(
+      std::unique_ptr<device::BluetoothDiscoverySession> session);
+  ~DiscoverySession() override;
+
+  // mojom::DiscoverySession overrides:
+  void IsActive(const IsActiveCallback& callback) override;
+  void Stop(const StopCallback& callback) override;
+
+ private:
+  void OnStop(const StopCallback& callback);
+  void OnStopError(const StopCallback& callback);
+
+  // The underlying discovery session.
+  std::unique_ptr<device::BluetoothDiscoverySession> discovery_session_;
+
+  base::WeakPtrFactory<DiscoverySession> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(DiscoverySession);
+};
+
+}  // namespace bluetooth
+
+#endif