bluetooth: Add control for reading/writing of characteristics to internals page.

device/bluetooth/public/interfaces/device.mojom

Index: device/bluetooth/public/interfaces/device.mojom
diff --git a/device/bluetooth/public/interfaces/device.mojom b/device/bluetooth/public/interfaces/device.mojom
index 2e3773ac787d780f9e9f8eebf5b6d830b7565bfb..baa361150d058cc8660554e3e7fbda3fbe9ee7ab 100644
--- a/device/bluetooth/public/interfaces/device.mojom
+++ b/device/bluetooth/public/interfaces/device.mojom
@@ -15,6 +15,7 @@ import "device/bluetooth/public/interfaces/uuid.mojom";
 // contains additional properties pertaining to the characteristic.
 // The properties |RELIABLE_WRITE| and |WRITABLE_AUXILIARIES| are retrieved from
 // that characteristic.
+// TODO(crbug.com/684168): Remove assignment of values when this is automated.
 enum Property {
   NONE = 0,
   BROADCAST = 1,
@@ -33,6 +34,20 @@ enum Property {
   WRITE_ENCRYPTED_AUTHENTICATED = 8192
 };
 
+enum GattResult {
+  SUCCESS,
+  UNKNOWN,
+  FAILED,
+  IN_PROGRESS,
+  INVALID_LENGTH,
+  NOT_PERMITTED,
+  NOT_AUTHORIZED,
+  NOT_PAIRED,
+  NOT_SUPPORTED,
+  SERVICE_NOT_FOUND,
+  CHARACTERISTIC_NOT_FOUND
+};
+
 // TODO(crbug.com/657632): Remove when numerical values can be optional.
 struct RSSIWrapper {
   int8 value;
@@ -56,6 +71,7 @@ struct CharacteristicInfo {
   string id;
   UUID uuid;
   uint32 properties;
+  array<uint8> last_known_value;
 };
 
 struct DescriptorInfo {
@@ -81,6 +97,16 @@ interface Device {
   GetCharacteristics(string service_id) =>
       (array<CharacteristicInfo>? characteristics);
 
+  // Reads the value for the GATT Characteristic with |characteristic_id| in
+  // the GATT Service with |service_id|.
+  ReadValueForCharacteristic(string service_id, string characteristic_id) =>
+      (GattResult result, array<uint8>? value);
+
+  // Writes the |value| to the GATT Characteristic with |characteristic_id| in
+  // the GATT Service with |service_id|.
+  WriteValueForCharacteristic(string service_id, string characteristic_id,
+      array<uint8> value) => (GattResult result);
+
   // Gets the GATT Descriptors of the GATT Characteristic with matching
   // |characteristic_id| in the GATT Service with matching |service_id|.
   // If |descriptors| is null, an error occured while attempting to retrieve