Implement WebContentsView::GetDropData for Mac; disable on Aura

content/browser/web_contents/web_contents_view_mac.mm

 // Copyright (c) 2012 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.
 
 #import <Carbon/Carbon.h>
 
 #import "content/browser/web_contents/web_contents_view_mac.h"
 
 #include <string>
 
@@ skipping 230 matching lines @@
 }
 
 bool WebContentsViewMac::IsDoingDrag() const {
   return false;
 }
 
 void WebContentsViewMac::CancelDragAndCloseTab() {
 }
 
 WebDropData* WebContentsViewMac::GetDropData() const {
-  return NULL;
+  return [dragDest_ currentDropData];
 }
 
 void WebContentsViewMac::UpdateDragCursor(WebDragOperation operation) {
   [cocoa_view_ setCurrentDragOperation: operation];
 }
 
 void WebContentsViewMac::GotFocus() {
   // This is only used in the views FocusManager stuff but it bleeds through
   // all subclasses. http://crbug.com/21875
 }
@@ skipping 312 matching lines @@
       [[[notification userInfo] objectForKey:kSelectionDirection]
         unsignedIntegerValue];
   if (direction == NSDirectSelection)
     return;
 
   [self webContents]->
       FocusThroughTabTraversal(direction == NSSelectingPrevious);
 }
 
 @end