device/bluetooth: Update GATT descriptor value D-Bus bindings.

chromeos/dbus/bluetooth_gatt_descriptor_client.h

Index: chromeos/dbus/bluetooth_gatt_descriptor_client.h
diff --git a/chromeos/dbus/bluetooth_gatt_descriptor_client.h b/chromeos/dbus/bluetooth_gatt_descriptor_client.h
index 3a7a26f57b2b773c69c9519b1836a98460dbb361..c3f24ac4ba2fdc1bdb0ba400892134cbb046657c 100644
--- a/chromeos/dbus/bluetooth_gatt_descriptor_client.h
+++ b/chromeos/dbus/bluetooth_gatt_descriptor_client.h
@@ -8,6 +8,7 @@
 #include <string>
 
 #include "base/basictypes.h"
+#include "base/callback.h"
 #include "chromeos/chromeos_export.h"
 #include "chromeos/dbus/dbus_client.h"
 #include "dbus/object_path.h"
@@ -28,11 +29,6 @@ class CHROMEOS_EXPORT BluetoothGattDescriptorClient : public DBusClient {
     // [read-only]
     dbus::Property<dbus::ObjectPath> characteristic;
 
-    // Raw characteristic descriptor value read from the remote Bluetooth
-    // device. Setting the value sends a write request to the remote device.
-    // [read-write]
-    dbus::Property<std::vector<uint8> > value;
-
     Properties(dbus::ObjectProxy* object_proxy,
                const std::string& interface_name,
                const PropertyChangedCallback& callback);
@@ -60,6 +56,11 @@ class CHROMEOS_EXPORT BluetoothGattDescriptorClient : public DBusClient {
         const std::string& property_name) {}
   };
 
+  // Callbacks used to report the result of asynchronous methods.
+  typedef base::Callback<void(const std::string& error_name,
+                              const std::string& error_message)> ErrorCallback;
+  typedef base::Callback<void(const std::vector<uint8>& value)> ValueCallback;
+
   virtual ~BluetoothGattDescriptorClient();
 
   // Adds and removes observers for events on all remote GATT descriptors. Check
@@ -75,9 +76,28 @@ class CHROMEOS_EXPORT BluetoothGattDescriptorClient : public DBusClient {
   // |object_path|. Values should be copied if needed.
   virtual Properties* GetProperties(const dbus::ObjectPath& object_path) = 0;
 
+  // Issues a request to read the value of GATT descriptor with object path
+  // |object_path| and returns the value in |callback| on success. On error,
+  // invokes |error_callback|.
+  virtual void ReadValue(const dbus::ObjectPath& object_path,
+                         const ValueCallback& callback,
+                         const ErrorCallback& error_callback) = 0;
+
+  // Issues a request to write the value of GATT descriptor with object path
+  // |object_path| with value |value|. Invokes |callback| on success and
+  // |error_callback| on failure.
+  virtual void WriteValue(const dbus::ObjectPath& object_path,
+                          const std::vector<uint8>& value,
+                          const base::Closure& callback,
+                          const ErrorCallback& error_callback) = 0;
+
   // Creates the instance.
   static BluetoothGattDescriptorClient* Create();
 
+  // Constants used to indicate exceptional error conditions.
+  static const char kNoResponseError[];
+  static const char kUnknownDescriptorError[];
+
  protected:
   BluetoothGattDescriptorClient();