convert //gpu to std::unique_ptr

gpu/ipc/service/ca_layer_tree_mac.mm

 // 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 "gpu/ipc/service/ca_layer_tree_mac.h"
 
 #include <AVFoundation/AVFoundation.h>
 #include <CoreMedia/CoreMedia.h>
 #include <CoreVideo/CoreVideo.h>
 
@@ skipping 125 matching lines @@
   if (has_committed_) {
     LOG(ERROR) << "ScheduleCALayer called after CommitScheduledCALayers.";
     return false;
   }
   return root_layer_.AddContentLayer(is_clipped, clip_rect, sorting_context_id,
                                      transform, io_surface, contents_rect, rect,
                                      background_color, edge_aa_mask, opacity);
 }
 
 void CALayerTree::CommitScheduledCALayers(CALayer* superlayer,
-                                          scoped_ptr<CALayerTree> old_tree,
+                                          std::unique_ptr<CALayerTree> old_tree,
                                           float scale_factor) {
   TRACE_EVENT0("gpu", "CALayerTree::CommitScheduledCALayers");
   RootLayer* old_root_layer = nullptr;
   if (old_tree) {
     DCHECK(old_tree->has_committed_);
     if (old_tree->scale_factor_ == scale_factor)
       old_root_layer = &old_tree->root_layer_;
   }
 
   root_layer_.CommitToCA(superlayer, old_root_layer, scale_factor);
@@ skipping 405 matching lines @@
     } else {
       // Grey represents a CALayer that has not changed.
       color.reset(CGColorCreateGenericRGB(0, 0, 0, 0.1));
     }
     [ca_layer setBorderWidth:1];
     [ca_layer setBorderColor:color];
   }
 }
 
 }  // namespace gpu