bluetooth: Blink-side implementation of getCharacteristic.

Source/modules/bluetooth/BluetoothGATTService.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef BluetoothGATTService_h
 #define BluetoothGATTService_h
 
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "platform/heap/Handle.h"
 #include "public/platform/modules/bluetooth/WebBluetoothGATTService.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
 
+class ScriptPromise;
 class ScriptPromiseResolver;
+class ScriptState;
 
 // Represents a GATT Service within a Bluetooth Peripheral, a collection of
 // characteristics and relationships to other services that encapsulate the
 // behavior of part of a device.
 //
 // Callbacks providing WebBluetoothGATTService objects are handled by
 // CallbackPromiseAdapter templatized with this class. See this class's
 // "Interface required by CallbackPromiseAdapter" section and the
 // CallbackPromiseAdapter class comments.
 class BluetoothGATTService final
     : public GarbageCollectedFinalized<BluetoothGATTService>
     , public ScriptWrappable {
     DEFINE_WRAPPERTYPEINFO();
 public:
     explicit BluetoothGATTService(const WebBluetoothGATTService&);
 
     // Interface required by CallbackPromiseAdapter:
     typedef WebBluetoothGATTService WebType;
     static BluetoothGATTService* take(ScriptPromiseResolver*, WebBluetoothGATTService*);
     static void dispose(WebBluetoothGATTService*);
 
     // Interface required by garbage collection.
     DEFINE_INLINE_TRACE() { }
 
     // IDL exposed interface:
     String uuid() { return m_webService.uuid; }
     bool isPrimary() { return m_webService.isPrimary; }
+    ScriptPromise getCharacteristic(ScriptState*, String characteristicUUID);
 
 private:
     WebBluetoothGATTService m_webService;
 };
 
 } // namespace blink
 
 #endif // BluetoothGATTService_h