bluetooth: {start,stop}Notifications() return the characteristic

third_party/WebKit/Source/modules/bluetooth/BluetoothRemoteGATTCharacteristic.cpp

 // 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.
 
 #include "modules/bluetooth/BluetoothRemoteGATTCharacteristic.h"
 
 #include "bindings/core/v8/CallbackPromiseAdapter.h"
 #include "bindings/core/v8/ScriptPromise.h"
 #include "bindings/core/v8/ScriptPromiseResolver.h"
 #include "core/dom/DOMDataView.h"
@@ skipping 177 matching lines @@
     WebVector<uint8_t> valueVector(value.bytes(), value.byteLength());
 
     ScriptPromiseResolver* resolver = ScriptPromiseResolver::create(scriptState);
 
     ScriptPromise promise = resolver->promise();
     webbluetooth->writeValue(m_webCharacteristic->characteristicInstanceID, valueVector, new WriteValueCallback(this, resolver));
 
     return promise;
 }
 
+class NotificationsCallback : public WebBluetoothNotificationsCallbacks {
+public:
+    NotificationsCallback(BluetoothRemoteGATTCharacteristic* characteristic, ScriptPromiseResolver* resolver) : m_webCharacteristic(characteristic), m_resolver(resolver) {}
+
+    void onSuccess() override
+    {
+        if (!m_resolver->getExecutionContext() || m_resolver->getExecutionContext()->activeDOMObjectsAreStopped())
+            return;
+
+        m_resolver->resolve(m_webCharacteristic);
+    }
+
+    void onError(int32_t error /* Corresponds to WebBluetoothError in web_bluetooth.mojom */) override
+    {
+        if (!m_resolver->getExecutionContext() || m_resolver->getExecutionContext()->activeDOMObjectsAreStopped())
+            return;
+        m_resolver->reject(BluetoothError::take(m_resolver, error));
+    }
+
+private:
+    WeakPersistent<BluetoothRemoteGATTCharacteristic> m_webCharacteristic;

[ortuno, 2016/08/05 01:43:44]

This needs to be Persistent. Otherwise you might resolve the promise with null.

[haraken, 2016/08/05 04:27:58]

Are you sure that the persistents don't create a cycle? i.e., is it guaranteed
that onSuccess or onError is called in a finite time period?

[ortuno, 2016/08/05 14:35:38]

Yes, it's guaranteed. If we don't ever call onSuccess or onError then it's a bug
on our mojo service.

+    Persistent<ScriptPromiseResolver> m_resolver;
+};
+
 ScriptPromise BluetoothRemoteGATTCharacteristic::startNotifications(ScriptState* scriptState)
 {
     WebBluetooth* webbluetooth = BluetoothSupplement::fromScriptState(scriptState);
     ScriptPromiseResolver* resolver = ScriptPromiseResolver::create(scriptState);
     ScriptPromise promise = resolver->promise();
-    webbluetooth->startNotifications(m_webCharacteristic->characteristicInstanceID, new CallbackPromiseAdapter<void, BluetoothError>(resolver));
+    webbluetooth->startNotifications(m_webCharacteristic->characteristicInstanceID, new NotificationsCallback(this, resolver));
     return promise;
 }
 
 ScriptPromise BluetoothRemoteGATTCharacteristic::stopNotifications(ScriptState* scriptState)
 {
 #if OS(MACOSX) || OS(ANDROID)
     // TODO(jlebel): Remove when stopNotifications is implemented.
     // TODO(scheib): Remove when stopNotifications is implemented.
     return ScriptPromise::rejectWithDOMException(scriptState,
         DOMException::create(NotSupportedError,
             "stopNotifications is not implemented yet. See https://goo.gl/J6ASzs"));
 #endif // OS(MACOSX) || OS(ANDROID)
 
     WebBluetooth* webbluetooth = BluetoothSupplement::fromScriptState(scriptState);
     ScriptPromiseResolver* resolver = ScriptPromiseResolver::create(scriptState);
     ScriptPromise promise = resolver->promise();
-    webbluetooth->stopNotifications(m_webCharacteristic->characteristicInstanceID, new CallbackPromiseAdapter<void, BluetoothError>(resolver));
+    webbluetooth->stopNotifications(m_webCharacteristic->characteristicInstanceID, new NotificationsCallback(this, resolver));
     return promise;
 }
 
 DEFINE_TRACE(BluetoothRemoteGATTCharacteristic)
 {
     visitor->trace(m_service);
     visitor->trace(m_properties);
     visitor->trace(m_value);
     EventTargetWithInlineData::trace(visitor);
     ActiveDOMObject::trace(visitor);
 }
 
 } // namespace blink