Views a11y: Implement AXPlatformNode::FromNativeViewAccessible on all platforms.

ui/views/accessibility/native_view_accessibility_mac.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.
 
 #include "ui/views/accessibility/native_view_accessibility_mac.h"
 
-#include <memory>
-
-#include "base/memory/ptr_util.h"
 #include "ui/views/view.h"
 #include "ui/views/widget/widget.h"
 
 namespace views {
 
 // static
-std::unique_ptr<NativeViewAccessibility> NativeViewAccessibility::Create(
-    View* view) {
-  return base::MakeUnique<NativeViewAccessibilityMac>(view);
+NativeViewAccessibility* NativeViewAccessibility::Create(View* view) {
+  return new NativeViewAccessibilityMac(view);
 }
 
 NativeViewAccessibilityMac::NativeViewAccessibilityMac(View* view)
     : NativeViewAccessibility(view) {}
 
 gfx::NativeViewAccessible NativeViewAccessibilityMac::GetParent() {
   if (view_->parent())
     return view_->parent()->GetNativeViewAccessible();
 
   if (view_->GetWidget())
     return view_->GetWidget()->GetNativeView();
 
   if (parent_widget_)
     return parent_widget_->GetRootView()->GetNativeViewAccessible();
 
   return nullptr;
 }
 
 }  // namespace views