bluetooth: Implement allowed devices map

content/browser/bluetooth/bluetooth_allowed_devices_map.h

+// Copyright 2015 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 CONTENT_BROWSER_BLUETOOTH_BLUETOOTH_ALLOWED_DEVICES_MAP_
+#define CONTENT_BROWSER_BLUETOOTH_BLUETOOTH_ALLOWED_DEVICES_MAP_
+
+#include <map>
+#include <set>
+#include <vector>
+
+#include "base/memory/scoped_ptr.h"
+#include "content/common/content_export.h"
+#include "url/origin.h"
+
+namespace device {
+class BluetoothUUID;
+}
+
+namespace content {
+
+struct BluetoothScanFilter;
+
+// Keeps track of which origins are allowed to access which devices and
+// their services.
+//
+// When talking about |device_id|s we are referring to
+// the generated |device_id| for each origin for a given device.

[palmer, 2016/01/15 01:13:59]

Nit: I'd reword this comment, along these lines:

    |AddDevice| generates device IDs, which are random strings that are unique
for each (origin, device address) pair. 

(The |...| notation should be reserved for specific identifiers.)

[ortuno, 2016/01/15 02:52:21]

Done.

+class CONTENT_EXPORT BluetoothAllowedDevicesMap final {
+ public:
+  BluetoothAllowedDevicesMap();
+  ~BluetoothAllowedDevicesMap();
+
+  // Adds the Bluetooth Device with |device_address| to the map of allowed
+  // devices for that origin. Returns the generated |device_id| for |origin|

[palmer, 2016/01/15 01:13:59]

...then you can change the last sentence in this comment to something like:

    Generates and returns a device ID for the (|origin|, |device_address|) pair.

[ortuno, 2016/01/15 02:52:22]

Done.

+  // for the device with |device_address|.
+  const std::string& AddDevice(
+      const url::Origin& origin,
+      const std::string& device_address,
+      const std::vector<BluetoothScanFilter>& filters,
+      const std::vector<device::BluetoothUUID>& optional_services);
+
+  // Removes the Bluetooth Device with |device_address| from the map of allowed
+  // devices for |origin|.
+  void RemoveDevice(const url::Origin& origin,
+                    const std::string& device_address);
+
+  // TODO(ortuno): Add function to check if origin is allowed to access
+  // a device's service and add tests for that function.
+  // https://crbug.com/493460
+
+  // Returns the Bluetooth Device's id for |origin|. Returns an empty string
+  // if the origin is not allowed to access the device.
+  const std::string& GetDeviceId(const url::Origin& origin,
+                                 const std::string& device_address);
+
+  // Returns the Bluetooth Device's address from |device_id_for_origin|. Returns

[palmer, 2016/01/15 01:13:59]

Minor Nit: Maybe word this in such a way that the comment for this public
function does not depend on the reader knowing about a private data member?
Something like:

    For |device_id| in |origin|, returns the Bluetooth device's address. If
there is no such |device_id| in |origin|, returns an empty string.

[ortuno, 2016/01/15 02:52:21]

Done.

+  // an empty string if the origin is not allowed to access the device.
+  const std::string& GetDeviceAddress(const url::Origin& origin,
+                                      const std::string& device_id);
+
+ private:
+  typedef std::map<std::string, std::string> DeviceAddressToIdMap;
+  typedef std::map<std::string, std::string> DeviceIdToAddressMap;
+  typedef std::map<std::string, std::set<std::string>> DeviceIdToServicesMap;
+
+  // Returns an id guaranteed to be unique for the origin. The id is randomly
+  // generated so that an origin can't guess the ID used in another origin.
+  std::string GenerateDeviceId(const url::Origin& origin);
+  std::set<std::string> UnionOfServices(
+      const std::vector<BluetoothScanFilter>& filters,
+      const std::vector<device::BluetoothUUID>& optional_services);
+
+  std::map<url::Origin, DeviceAddressToIdMap>

[palmer, 2016/01/15 01:13:59]

This 3-way mapping system seems complex. I wonder if it could be simplified,
such as by combining  the origin and the UUID?

    device-id := origin + "," + uuid

or the like? Perhaps you've already considered this and rejected it. Just an
idea.

[ortuno, 2016/01/15 02:52:22]

Interesting. This class implements the spec so I opened an issue there:
https://github.com/WebBluetoothCG/web-bluetooth/issues/199

+      origin_to_device_address_to_id_map_;
+  std::map<url::Origin, DeviceIdToAddressMap>
+      origin_to_device_id_to_address_map_;
+  std::map<url::Origin, DeviceIdToServicesMap>
+      origin_to_device_id_to_services_map_;
+};
+
+}  //  namespace content
+
+#endif  // CONTENT_BROWSER_BLUETOOTH_BLUETOOTH_ALLOWED_DEVICES_MAP_