Allow OSExchangeData::Provider to be overridden at run time.

ui/views/widget/desktop_aura/desktop_drop_target_win.cc

 // Copyright (c) 2011 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 "ui/views/widget/desktop_aura/desktop_drop_target_win.h"
 
+#include "base/memory/ptr_util.h"
 #include "base/metrics/histogram.h"
 #include "base/win/win_util.h"
 #include "ui/aura/window.h"
 #include "ui/aura/window_tree_host.h"
 #include "ui/base/dragdrop/drag_drop_types.h"
 #include "ui/base/dragdrop/drop_target_event.h"
 #include "ui/base/dragdrop/os_exchange_data_provider_win.h"
 #include "ui/events/event_constants.h"
 #include "ui/wm/public/drag_drop_client.h"
 #include "ui/wm/public/drag_drop_delegate.h"
@@ skipping 124 matching lines @@
       target_window_->AddObserver(this);
     target_window_changed = true;
   }
   *delegate = NULL;
   if (!target_window_)
     return;
   *delegate = aura::client::GetDragDropDelegate(target_window_);
   if (!*delegate)
     return;
 
-  data->reset(new OSExchangeData(new OSExchangeDataProviderWin(data_object)));
+  data->reset(new OSExchangeData(
+      base::MakeUnique<OSExchangeDataProviderWin>(data_object)));
   location = root_location;
   aura::Window::ConvertPointToTarget(root_window_, target_window_, &location);
   event->reset(new ui::DropTargetEvent(
       *(data->get()),
       location,
       root_location,
       ui::DragDropTypes::DropEffectToDragOperation(effect)));
   (*event)->set_flags(ConvertKeyStateToAuraEventFlags(key_state));
   if (target_window_changed)
     (*delegate)->OnDragEntered(*event->get());
 }
 
 void DesktopDropTargetWin::NotifyDragLeave() {
   if (!target_window_)
     return;
   DragDropDelegate* delegate =
       aura::client::GetDragDropDelegate(target_window_);
   if (delegate)
     delegate->OnDragExited();
   target_window_->RemoveObserver(this);
   target_window_ = NULL;
 }
 
 }  // namespace views