bluetooth: Create base class BluetoothDevice::CreateGattConnection impl.

device/bluetooth/bluetooth_device.h

Index: device/bluetooth/bluetooth_device.h
diff --git a/device/bluetooth/bluetooth_device.h b/device/bluetooth/bluetooth_device.h
index 67948f800b92fb36ca8e046a080e3717b5652435..0eae80850c2d9999a87c61b91c2c8756a2662b43 100644
--- a/device/bluetooth/bluetooth_device.h
+++ b/device/bluetooth/bluetooth_device.h
@@ -240,6 +240,9 @@ class DEVICE_BLUETOOTH_EXPORT BluetoothDevice {
   // they could be connected to the adapter but not to an application.
   virtual bool IsConnected() const = 0;
 
+  // Indicates whether an active GATT connection exists to the device.
+  virtual bool IsGattConnected() const = 0;
+
   // Indicates whether the paired device accepts connections initiated from the
   // adapter. This value is undefined for unpaired devices.
   virtual bool IsConnectable() const = 0;
@@ -407,9 +410,8 @@ class DEVICE_BLUETOOTH_EXPORT BluetoothDevice {
   // BluetoothAdapter::Observer::DeviceChanged method.
   typedef base::Callback<void(scoped_ptr<BluetoothGattConnection>)>
       GattConnectionCallback;
-  virtual void CreateGattConnection(
-      const GattConnectionCallback& callback,
-      const ConnectErrorCallback& error_callback) = 0;
+  virtual void CreateGattConnection(const GattConnectionCallback& callback,
+                                    const ConnectErrorCallback& error_callback);
 
   // Returns the list of discovered GATT services.
   virtual std::vector<BluetoothGattService*> GetGattServices() const;
@@ -431,11 +433,37 @@ class DEVICE_BLUETOOTH_EXPORT BluetoothDevice {
   static std::string CanonicalizeAddress(const std::string& address);
 
  protected:
+  // BluetoothGattConnection is a friend to call
+  // In/DecrementGattConnectionReferenceCount.

[Jeffrey Yasskin, 2015/08/19 22:49:45]

"Inc/Decrement", I think.

[scheib, 2015/09/13 02:40:27]

Done.

+  friend BluetoothGattConnection;
+
   BluetoothDevice(BluetoothAdapter* adapter);
 
   // Returns the internal name of the Bluetooth device, used by GetName().
   virtual std::string GetDeviceName() const = 0;
 
+  // Implements platform specific operations to initiate a GATT connection.
+  // Subclasses must also call DidConnectGatt, DidFailToConnectGatt, or
+  // DidDisconnectGatt immediately or asynchronously as the connection state

[Jeffrey Yasskin, 2015/08/19 22:49:45]

"immediately or asynchronously" covers all the options, so you can probably skip
it.

[scheib, 2015/09/13 02:40:27]

Done. I was trying to communicate that these may be called safely at any time.

[Jeffrey Yasskin, 2015/09/16 00:45:39]

Ah, yeah, I like the explicit statement you've added to those functions that
they can be called at any time.

You didn't remove the "immediately or asynchronously" here. I don't insist, but
still think it's extraneous.

+  // changes.
+  virtual void CreateGattConnectionImpl() = 0;

[Jeffrey Yasskin, 2015/08/19 22:49:45]

If you intend to only call this from BluetoothDevice, it should be private.
Subclasses can still override private members.

[scheib, 2015/09/13 02:40:28]

Doesn't overriding for implementation then defeat the private scoping? I'm not
sure how this adds compile safety, but I do see that it will split related
methods to be non contiguous.

[Jeffrey Yasskin, 2015/09/16 00:45:39]

Yeah, good point: subclasses will be able to call their own overrides. Making
the function private still makes it clear that the base class doesn't intend to
provide any service to the subclasses through this function, but, on the other
hand, the =0 makes the same statement, so I guess it doesn't matter much.

+
+  // Disconnects GATT connection on platforms that maintain a specific GATT
+  // connection.
+  virtual void DisconnectGatt() = 0;
+
+  // Calls pending callbacks for CreateGattConnection based on result of

[Jeffrey Yasskin, 2015/08/19 22:49:45]

Say something about how Did*Gatt() calls need to match up with
CreateGattConnectionImpl and DisconnectGatt calls. Are they 1-1? Can Did*Gatt()
calls come in spontaneously? Does one of these report the device going out of
range?

[scheib, 2015/09/13 02:40:27]

Done. Regarding out of range, there isn't anything specific in this design that
addresses out of range - but if the platform indicates that the GATT connection
is disconnected then DidDisconnectGatt is the only expected API point to call.
BluetoothDevice doesn't otherwise make any statements about out of range.

+  // subclasses actions initiated in CreateGattConnectionImpl or related
+  // disconnection event.
+  void DidConnectGatt();
+  void DidFailToConnectGatt(ConnectErrorCode);
+  void DidDisconnectGatt();
+
+  // Maintains GattConnection reference count. Called by friend class
+  // BluetoothGattConnection.
+  void IncrementGattConnectionReferenceCount();
+  void DecrementGattConnectionReferenceCount();
+
   // Clears the list of service data.
   void ClearServiceData();
 
@@ -447,6 +475,14 @@ class DEVICE_BLUETOOTH_EXPORT BluetoothDevice {
   // specific pointers via adapter_.
   BluetoothAdapter* adapter_;
 
+  // Callbacks for pending success and error result of CreateGattConnection.
+  std::vector<GattConnectionCallback> create_gatt_connection_success_callbacks_;
+  std::vector<ConnectErrorCallback> create_gatt_connection_error_callbacks_;
+
+  // Represents the number of BluetoothGattConnection objects keeping the
+  // Gatt connection alive to the device.
+  uint32_t gatt_connection_reference_count_ = 0;
+
   // Mapping from the platform-specific GATT service identifiers to
   // BluetoothGattService objects.
   typedef std::map<std::string, BluetoothGattService*> GattServiceMap;