components/arc: implement multi advertising

components/arc/bluetooth/arc_bluetooth_bridge.h

Index: components/arc/bluetooth/arc_bluetooth_bridge.h
diff --git a/components/arc/bluetooth/arc_bluetooth_bridge.h b/components/arc/bluetooth/arc_bluetooth_bridge.h
index c1a6ade02b395302cca0302fb0cefdd8e0974edb..3dc6c5aa0ed8929047c2c692313ff89b05156c0c 100644
--- a/components/arc/bluetooth/arc_bluetooth_bridge.h
+++ b/components/arc/bluetooth/arc_bluetooth_bridge.h
@@ -19,6 +19,7 @@
 #include "components/arc/instance_holder.h"
 #include "device/bluetooth/bluetooth_adapter.h"
 #include "device/bluetooth/bluetooth_adapter_factory.h"
+#include "device/bluetooth/bluetooth_advertisement.h"
 #include "device/bluetooth/bluetooth_device.h"
 #include "device/bluetooth/bluetooth_discovery_session.h"
 #include "device/bluetooth/bluetooth_local_gatt_service.h"
@@ -266,6 +267,17 @@ class ArcBluetoothBridge
                       mojo::Array<uint8_t> value,
                       const SendIndicationCallback& callback) override;
 
+  // Set up or disable multiple advertising.
+  void ReserveAdvertisementHandle(
+      const ReserveAdvertisementHandleCallback& callback) override;
+  void BroadcastAdvertisement(
+      int32_t adv_handle,
+      mojom::BluetoothAdvertisementPtr advertisement,
+      const BroadcastAdvertisementCallback& callback) override;
+  void ReleaseAdvertisementHandle(
+      int32_t adv_handle,
+      const ReleaseAdvertisementHandleCallback& callback) override;
+
   // Chrome observer callbacks
   void OnPoweredOn(
       const base::Callback<void(mojom::BluetoothAdapterState)>& callback) const;
@@ -360,6 +372,42 @@ class ArcBluetoothBridge
                                    const base::Closure& success_callback,
                                    const ErrorCallback& error_callback);
 
+  // Callbacks for managing advertisements registered from the instance.
+
+  // Called when we have an open slot in the advertisement map and want to
+  // register the advertisement given by |data| for handle |adv_handle|.
+  void OnReadyToRegisterAdvertisement(
+      const BroadcastAdvertisementCallback& callback,
+      int32_t adv_handle,
+      std::unique_ptr<device::BluetoothAdvertisement::Data> data);
+  // Called when we've successfully registered a new advertisement for
+  // handle |adv_handle|.
+  void OnRegisterAdvertisementDone(
+      const BroadcastAdvertisementCallback& callback,
+      int32_t adv_handle,
+      scoped_refptr<device::BluetoothAdvertisement> advertisement);
+  // Called when the attempt to register an advertisement for handle
+  // |adv_handle| has failed. |adv_handle| remains reserved, but no
+  // advertisement is associated with it.
+  void OnRegisterAdvertisementError(
+      const BroadcastAdvertisementCallback& callback,
+      int32_t adv_handle,
+      device::BluetoothAdvertisement::ErrorCode error_code);
+  // Both of the following are called after we've tried to unregister
+  // the advertisement for |adv_handle|. Either way, we will no
+  // longer be broadcasting this advertisement, so in either case, the
+  // handle can be released.
+  void OnUnregisterAdvertisementDone(
+      const ReleaseAdvertisementHandleCallback& callback,
+      int32_t adv_handle);
+  void OnUnregisterAdvertisementError(
+      const ReleaseAdvertisementHandleCallback& callback,
+      int32_t adv_handle,
+      device::BluetoothAdvertisement::ErrorCode error_code);
+  // Find the next free advertisement handle and put it in *adv_handle,
+  // or return false if the advertisement map is full.
+  bool GetAdvertisementHandle(int32_t* adv_handle);
+
   bool CalledOnValidThread();
 
   mojo::Binding<mojom::BluetoothHost> binding_;
@@ -381,6 +429,11 @@ class ArcBluetoothBridge
   // Keeps track of all devices which initiated a GATT connection to us.
   std::unordered_set<std::string> gatt_connection_cache_;
 
+  // Holds advertising data registered by the instance.
+  static constexpr uint16_t kMaxAdvertisements = 5;
+  std::map<int32_t, scoped_refptr<device::BluetoothAdvertisement>>

[rickyz (no longer on Chrome), 2016/08/24 21:47:30]

Did you see rkc's comment on using std::array for this instead?

[Eric Caruso, 2016/08/24 22:24:42]

The design changed, and I got rid of AdvertisementInstance. I might also change
the keying to be simpler as puthik@ suggested, which would make std::array hard
to use for this.

Currently, the advertisements_ structure is to be interpreted as follows:
* key does not exist -> handle is free
* key exists, but value is nullptr -> handle is reserved and no advertisement is
registered
* key exists and value is not nullptr -> handle is reserved and in use.

If I did use std::array, the equivalent here would be some kind of optional type
for the scoped_refptr:
base::Optional<scoped_refptr<device::BluetoothAdvertisement>> (since we don't
have std::optional until C++17). Otherwise it would be difficult to encode the
reserved-but-unusued case. The above optional type allows me to encode it, but
in a weird way that I don't think is very easy to understand. I'd rather not go
back to a struct with an in-use bool either, since that was elided in favor of
stashing the struct in an std::unique_ptr to begin with.

+      advertisements_;
+
   base::ThreadChecker thread_checker_;
 
   // WeakPtrFactory to use for callbacks.