Implement WebBluetooth getDescriptor[s]

third_party/WebKit/public/platform/modules/bluetooth/web_bluetooth.mojom

Index: third_party/WebKit/public/platform/modules/bluetooth/web_bluetooth.mojom
diff --git a/third_party/WebKit/public/platform/modules/bluetooth/web_bluetooth.mojom b/third_party/WebKit/public/platform/modules/bluetooth/web_bluetooth.mojom
index b1eca7bc2de49c90ab832bf01744fb4305c8f2c1..34845337eef5125be434d5a52ce5719f0117925d 100644
--- a/third_party/WebKit/public/platform/modules/bluetooth/web_bluetooth.mojom
+++ b/third_party/WebKit/public/platform/modules/bluetooth/web_bluetooth.mojom
@@ -51,6 +51,8 @@ enum WebBluetoothResult {
   NO_SERVICES_FOUND,
   CHARACTERISTIC_NOT_FOUND,
   NO_CHARACTERISTICS_FOUND,
+  DESCRIPTOR_NOT_FOUND,
+  NO_DESCRIPTORS_FOUND,
   WEB_BLUETOOTH_NOT_SUPPORTED,
   BLUETOOTH_LOW_ENERGY_NOT_AVAILABLE,
   // NotSupportedError:
@@ -61,6 +63,7 @@ enum WebBluetoothResult {
   GATT_UNTRANSLATED_ERROR_CODE,
   // SecurityError:
   GATT_NOT_AUTHORIZED,
+  BLOCKLISTED_DESCRIPTOR_UUID,
   BLOCKLISTED_CHARACTERISTIC_UUID,
   BLOCKLISTED_READ,
   BLOCKLISTED_WRITE,
@@ -110,6 +113,11 @@ struct WebBluetoothRemoteGATTCharacteristic {
   uint32 properties;
 };
 
+struct WebBluetoothRemoteGATTDescriptor {
+  string instance_id;
+  string uuid;

[dcheng, 2016/12/29 09:07:18]

What's instance_id? Can it be any arbitrary string? Is it ever parsed in some
way?

In general, these structs all need more documentation on what the freeform
string fields can hold. The pre-existing structs can be done in a followup, but
this new one should be documented.

Also, use bluetooth.mojom.UUID for the uuid?

[dougt, 2017/01/12 19:38:16]

Acknowledged.  Filed 676720.

[scheib, 2017/01/12 23:41:35]

https://bugs.chromium.org/p/chromium/issues/detail?id=680587 I think?

FYI: the IDs are platform specific opaque identifiers. Each platform generates
them differently, and e.g. on linux they come from the drivers, while on Android
we generate our own. They are not intended to be exposed to javascript code, but
are necessary for the renderer implementation to be able to refer to specific
instances.

+};
+
 // Web Bluetooth Interface that Blink can use to perform
 // Bluetooth GATT Operations on Bluetooth Devices.
 interface WebBluetoothService {
@@ -179,6 +187,16 @@ interface WebBluetoothService {
   // |characteristic_instance_id|.
   RemoteCharacteristicStopNotifications(
     string characteristic_instance_id) => ();
+
+  // Returns the Descriptors of a GATT Characteristic with |characteristics_instance_id|.
+  // If |quantity| == WebBluetoothGATTQueryQuantity::SINGLE, only one
+  // descriptor will be returned.
+  RemoteCharacteristicGetDescriptors(
+    string characteristics_instance_id,

[dcheng, 2016/12/29 09:07:18]

Similar question here: what is a characteristics_instance_id: is it any freeform
string or something more specific?

[dougt, 2017/01/12 19:38:16]

Acknowledged.

This is used id throughout. We can follow up and add better comments.

+    WebBluetoothGATTQueryQuantity quantity,
+    bluetooth.mojom.UUID? descriptor_uuid) => (
+      WebBluetoothResult result,
+      array<WebBluetoothRemoteGATTDescriptor>? descriptors);
 };
 
 // Classes should implement this interface and pass an associated pointer