Mac: Clean up plumbing of accelerated widgets

gpu/ipc/client/gpu_process_hosted_ca_layer_tree_params.h

 // Copyright 2016 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.
 
 #include <IOSurface/IOSurface.h>
 
 #include "base/mac/scoped_cftyperef.h"
 #include "gpu/command_buffer/common/texture_in_use_response.h"
 #include "gpu/gpu_export.h"
 #include "ui/base/cocoa/remote_layer_api.h"
 #include "ui/gfx/geometry/size.h"
 
 namespace gpu {
 
 struct GPU_EXPORT GpuProcessHostedCALayerTreeParamsMac {
   GpuProcessHostedCALayerTreeParamsMac();
   ~GpuProcessHostedCALayerTreeParamsMac();
 
-  int surface_handle = 0;
   CAContextID ca_context_id = 0;
   bool fullscreen_low_power_ca_context_valid = false;
   CAContextID fullscreen_low_power_ca_context_id = 0;
   base::ScopedCFTypeRef<IOSurfaceRef> io_surface;
   gfx::Size pixel_size;
   float scale_factor = 1;
   TextureInUseResponses responses;
 };
 
 }  // namespace gpu