Only (and always) put URLs in NSLinkAttributeName.

ui/base/cocoa/controls/hyperlink_text_view.mm

 // 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.
 
 #import "ui/base/cocoa/controls/hyperlink_text_view.h"
 
+#include "base/logging.h"
 #include "base/mac/scoped_nsobject.h"
 #include "ui/base/cocoa/nsview_additions.h"
 
 // The baseline shift for text in the NSTextView.
 const float kTextBaselineShift = -1.0;
 
 @interface HyperlinkTextView(Private)
 // Initialize the NSTextView properties for this subclass.
 - (void)configureTextView;
 
@@ skipping 98 matching lines @@
   // Create the attributed string for the message.
   base::scoped_nsobject<NSAttributedString> attributedMessage(
       [[NSMutableAttributedString alloc] initWithString:message
                                              attributes:attributes]);
 
   // Update the text view with the new text.
   [[self textStorage] setAttributedString:attributedMessage];
 }
 
 - (void)addLinkRange:(NSRange)range
-            withName:(id)name
+             withURL:(NSString*)url
            linkColor:(NSColor*)linkColor {
+  // When the NSLinkAttributeName attribute is used, AppKit makes the link
+  // draggable. If no URL is provided, dropping it on the tab strip will crash
+  // <http://crbug.com/528228>. Require that a URL is used, and that only a URL
+  // is used.
+  DCHECK_GE([url length], 0u);
+  DCHECK([NSURL URLWithString:url]);
   NSDictionary* attributes = @{
     NSForegroundColorAttributeName : linkColor,
     NSUnderlineStyleAttributeName : @(YES),
     NSCursorAttributeName : [NSCursor pointingHandCursor],
-    NSLinkAttributeName : name,
+    NSLinkAttributeName : url,
     NSUnderlineStyleAttributeName : @(NSSingleUnderlineStyle)
   };
 
   [[self textStorage] addAttributes:attributes range:range];
 }
 
 - (void)setRefusesFirstResponder:(BOOL)refusesFirstResponder {
   refusesFirstResponder_ = refusesFirstResponder;
 }
 
 @end