Implement WebBluetooth descriptor.readValue()

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

Index: third_party/WebKit/Source/modules/bluetooth/BluetoothDevice.cpp
diff --git a/third_party/WebKit/Source/modules/bluetooth/BluetoothDevice.cpp b/third_party/WebKit/Source/modules/bluetooth/BluetoothDevice.cpp
index dde3df2afd038565362397085a5b25020b1684b3..7669ccb13d98f54981810cda3957bbf07ffc36b7 100644
--- a/third_party/WebKit/Source/modules/bluetooth/BluetoothDevice.cpp
+++ b/third_party/WebKit/Source/modules/bluetooth/BluetoothDevice.cpp
@@ -71,6 +71,10 @@ BluetoothDevice::getOrCreateBluetoothRemoteGATTDescriptor(
       std::move(descriptor), characteristic);
 }
 
+bool BluetoothDevice::isValidDescriptor(const String& descriptorInstanceId) {
+  return m_attributeInstanceMap->containsDescriptor(descriptorInstanceId);
+}
+
 void BluetoothDevice::dispose() {
   disconnectGATTIfConnected();
 }