Implement DBus changes needed for notifications.

device/bluetooth/dbus/bluetooth_gatt_characteristic_service_provider_impl.cc

Index: device/bluetooth/dbus/bluetooth_gatt_characteristic_service_provider_impl.cc
diff --git a/device/bluetooth/dbus/bluetooth_gatt_characteristic_service_provider_impl.cc b/device/bluetooth/dbus/bluetooth_gatt_characteristic_service_provider_impl.cc
index d7acdb41c5bf41584d11328d52023ed00e5c12c9..97f36fac5ae395ac10fe6d3001f2bbf37c5588bb 100644
--- a/device/bluetooth/dbus/bluetooth_gatt_characteristic_service_provider_impl.cc
+++ b/device/bluetooth/dbus/bluetooth_gatt_characteristic_service_provider_impl.cc
@@ -40,9 +40,6 @@ BluetoothGattCharacteristicServiceProviderImpl::
       weak_ptr_factory_(this) {
   VLOG(1) << "Created Bluetooth GATT characteristic: " << object_path.value()
           << " UUID: " << uuid;
-
-  // If we have a null bus, this means that this is being initialized for a
-  // test, hence we shouldn't do any other setup.
   if (!bus_)
     return;
 
@@ -90,6 +87,20 @@ BluetoothGattCharacteristicServiceProviderImpl::
                  weak_ptr_factory_.GetWeakPtr()),
       base::Bind(&BluetoothGattCharacteristicServiceProviderImpl::OnExported,
                  weak_ptr_factory_.GetWeakPtr()));
+  exported_object_->ExportMethod(
+      bluetooth_gatt_characteristic::kBluetoothGattCharacteristicInterface,
+      bluetooth_gatt_characteristic::kStartNotify,
+      base::Bind(&BluetoothGattCharacteristicServiceProviderImpl::StartNotify,
+                 weak_ptr_factory_.GetWeakPtr()),
+      base::Bind(&BluetoothGattCharacteristicServiceProviderImpl::OnExported,
+                 weak_ptr_factory_.GetWeakPtr()));
+  exported_object_->ExportMethod(
+      bluetooth_gatt_characteristic::kBluetoothGattCharacteristicInterface,
+      bluetooth_gatt_characteristic::kStopNotify,
+      base::Bind(&BluetoothGattCharacteristicServiceProviderImpl::StopNotify,
+                 weak_ptr_factory_.GetWeakPtr()),
+      base::Bind(&BluetoothGattCharacteristicServiceProviderImpl::OnExported,
+                 weak_ptr_factory_.GetWeakPtr()));
 }
 
 BluetoothGattCharacteristicServiceProviderImpl::
@@ -102,6 +113,10 @@ BluetoothGattCharacteristicServiceProviderImpl::
 
 void BluetoothGattCharacteristicServiceProviderImpl::SendValueChanged(
     const std::vector<uint8_t>& value) {
+  // Running a test, don't actually try to write to use DBus.
+  if (!bus_)
+    return;
+
   VLOG(2) << "Emitting a PropertiesChanged signal for characteristic value.";
   dbus::Signal signal(dbus::kDBusPropertiesInterface,
                       dbus::kDBusPropertiesChangedSignal);
@@ -359,6 +374,46 @@ void BluetoothGattCharacteristicServiceProviderImpl::WriteValue(
                  weak_ptr_factory_.GetWeakPtr(), method_call, response_sender));
 }
 
+void BluetoothGattCharacteristicServiceProviderImpl::StartNotify(

[xiyuan, 2016/05/12 18:33:18]

Silly question: Why StartNotify do delegate_->GetValue and StopNotify do
delegate_->SetValue ?

It does not look like what I saw from bluez doc:
https://kernel.googlesource.com/pub/scm/bluetooth/bluez/+/master/doc/gatt-api...

It seems StartNotify should not return anything and StopNotify does not have any
input.

[rkc, 2016/05/12 19:51:50]

Ugh, this is really stupid of me. I apologize! This is of course, all wrong. I
copy/pasted the code from ReadValue/WriteValue and completely forgot to change
the actual implementation.

This is why we need end-to-end tests. :-\

Fixed.

+    dbus::MethodCall* method_call,
+    dbus::ExportedObject::ResponseSender response_sender) {
+  VLOG(3) << "BluetoothGattCharacteristicServiceProvider::StartNotify: "
+          << object_path_.value();
+  DCHECK(OnOriginThread());
+  DCHECK(delegate_);
+  delegate_->GetValue(
+      base::Bind(&BluetoothGattCharacteristicServiceProviderImpl::OnReadValue,
+                 weak_ptr_factory_.GetWeakPtr(), method_call, response_sender),
+      base::Bind(&BluetoothGattCharacteristicServiceProviderImpl::OnFailure,
+                 weak_ptr_factory_.GetWeakPtr(), method_call, response_sender));
+}
+
+void BluetoothGattCharacteristicServiceProviderImpl::StopNotify(
+    dbus::MethodCall* method_call,
+    dbus::ExportedObject::ResponseSender response_sender) {
+  VLOG(3) << "BluetoothGattCharacteristicServiceProvider::WriteValue: "

[xiyuan, 2016/05/12 18:33:18]

nit: update the message, WriteValue -> StopNotify?

[rkc, 2016/05/12 19:51:50]

Done.

+          << object_path_.value();
+  DCHECK(OnOriginThread());
+
+  dbus::MessageReader reader(method_call);
+  const uint8_t* bytes = NULL;
+  size_t length = 0;
+
+  if (!reader.PopArrayOfBytes(&bytes, &length))
+    VLOG(2) << "Error reading array of bytes in in WriteValue";

[xiyuan, 2016/05/12 18:33:18]

nit: update the message

[rkc, 2016/05/12 19:51:50]

Done.

+  std::vector<uint8_t> value;
+  if (bytes)
+    value.assign(bytes, bytes + length);
+
+  DCHECK(delegate_);
+  delegate_->SetValue(
+      value,
+      base::Bind(&BluetoothGattCharacteristicServiceProviderImpl::OnWriteValue,
+                 weak_ptr_factory_.GetWeakPtr(), method_call, response_sender),
+      base::Bind(&BluetoothGattCharacteristicServiceProviderImpl::OnFailure,
+                 weak_ptr_factory_.GetWeakPtr(), method_call, response_sender));
+}
+
 void BluetoothGattCharacteristicServiceProviderImpl::OnExported(
     const std::string& interface_name,
     const std::string& method_name,