Implement BluetoothGattNotifySession::Stop on Android, 2nd attempt

device/bluetooth/bluetooth_gatt_notify_session.cc

 // Copyright 2014 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.
 
 #include "device/bluetooth/bluetooth_gatt_notify_session.h"
 
+#include "base/bind.h"
+#include "base/logging.h"
+#include "device/bluetooth/bluetooth_remote_gatt_characteristic.h"
+
 namespace device {
 
-BluetoothGattNotifySession::BluetoothGattNotifySession() {
+BluetoothGattNotifySession::BluetoothGattNotifySession(
+    base::WeakPtr<BluetoothRemoteGattCharacteristic> characteristic)
+    : characteristic_(characteristic),
+      characteristic_id_(characteristic.get() ? characteristic->GetIdentifier()
+                                              : std::string()) {}
+
+BluetoothGattNotifySession::~BluetoothGattNotifySession() {
+  if (characteristic_.get()) {

[ortuno, 2016/07/28 21:59:29]

optional nit: I think the preferred method for checking that a WeakPtr is still
valid is to use its  !=(..., nullptr) operator:

characteristic_ != nullptr;

Alternative you could use IsActive():

if (IsActive()) {
  Stop(...);
}

[tommyt, 2016/08/01 11:39:21]

Done.

+    Stop(base::Bind(&base::DoNothing));
+  }
 }
 
-BluetoothGattNotifySession::~BluetoothGattNotifySession() {
+std::string BluetoothGattNotifySession::GetCharacteristicIdentifier() const {
+  return characteristic_id_;
+}
+
+BluetoothRemoteGattCharacteristic*
+BluetoothGattNotifySession::GetCharacteristic() const {
+  return characteristic_.get();
+}
+
+bool BluetoothGattNotifySession::IsActive() {
+  return characteristic_.get() != nullptr && characteristic_->IsNotifying();

[ortuno, 2016/07/28 21:59:30]

When would characteristic_.get() != nullptr and IsNotifying be false?

[tommyt, 2016/08/01 11:39:21]

Currently never. However, if we move towards creating session objects instantly
in StartNotifySession, this will be the case between the time when the session
object is created, until the characteristic successfully starts notifying.

+}
+
+void BluetoothGattNotifySession::Stop(const base::Closure& callback) {
+  BluetoothRemoteGattCharacteristic* characteristic = characteristic_.get();
+  characteristic_.reset();
+  if (characteristic) {

[ortuno, 2016/07/28 21:59:30]

optional nit for clarity: characteristic != nullptr 

[tommyt, 2016/08/01 11:39:21]

Done.

+    characteristic->StopNotifySession(this, callback);
+  } else {
+    callback.Run();
+  }
 }
 
 }  // namespace device