[CRD iOS] Fix the leaky RemotingClient

remoting/ios/display/gl_display_handler.mm

 // Copyright 2017 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.
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
 #endif
 
 #include <array>
 
@@ skipping 60 matching lines @@
   base::WeakPtr<RendererProxy> renderer_proxy_;
 
   // Will be std::move'd when GrabFrameConsumer() is called.
   std::unique_ptr<DualBufferFrameConsumer> owned_frame_consumer_;
   base::WeakPtr<DualBufferFrameConsumer> frame_consumer_;
 
   // TODO(yuweih): Release references once the surface is destroyed.
   EAGLContext* eagl_context_;
   std::unique_ptr<GlRenderer> renderer_;
   //  GlDemoScreen *demo_screen_;
-  id<GlDisplayHandlerDelegate> handler_delegate_;
+  __weak id<GlDisplayHandlerDelegate> handler_delegate_;
 
   // Used on display thread.
   base::WeakPtr<Core> weak_ptr_;
   base::WeakPtrFactory<Core> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(Core);
 };
 
 Core::Core() : weak_factory_(this) {
   runtime_ = ChromotingClientRuntime::GetInstance();
@@ skipping 198 matching lines @@
                  _core->GetWeakPtr(), delegate));
 }
 
 - (id<GlDisplayHandlerDelegate>)delegate {
   // Implementation is still required for UNAVAILABLE_ATTRIBUTE.
   NOTREACHED();
   return nil;
 }
 
 @end