Implement BluetoothGattNotifySession::Stop on Android, 2nd attempt

device/bluetooth/bluetooth_gatt_notify_session.cc

Index: device/bluetooth/bluetooth_gatt_notify_session.cc
diff --git a/device/bluetooth/bluetooth_gatt_notify_session.cc b/device/bluetooth/bluetooth_gatt_notify_session.cc
index 3c9a242388024c5321d4bf4bc1529bd1aaa98b23..cc0c89b2267a22276e40c7363c978a0cd76d3d6e 100644
--- a/device/bluetooth/bluetooth_gatt_notify_session.cc
+++ b/device/bluetooth/bluetooth_gatt_notify_session.cc
@@ -4,12 +4,45 @@
 
 #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));
+  }
+}
+
+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