Only (and always) put URLs in NSLinkAttributeName.

chrome/browser/ui/cocoa/tabs/tab_strip_controller.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 "chrome/browser/ui/cocoa/tabs/tab_strip_controller.h"
 
 #import <QuartzCore/QuartzCore.h>
 
 #include <cmath>
 #include <limits>
@@ skipping 2108 matching lines @@
   }
 
   //TODO(viettrungluu): dropping multiple URLs.
   if ([urls count] > 1)
     NOTIMPLEMENTED();
 
   // Get the first URL and fix it up.
   GURL url(GURL(url_formatter::FixupURL(
       base::SysNSStringToUTF8([urls objectAtIndex:0]), std::string())));
 
+  // If the URL isn't valid, don't bother.
+  if (!url.is_valid())
+    return;
+
   [self openURL:&url inView:view at:point];
 }
 
 // (URLDropTargetController protocol)
 - (void)dropText:(NSString*)text inView:(NSView*)view at:(NSPoint)point {
   DCHECK_EQ(view, tabStripView_.get());
 
   // If the input is plain text, classify the input and make the URL.
   AutocompleteMatch match;
   AutocompleteClassifierFactory::GetForProfile(browser_->profile())->Classify(
@@ skipping 184 matching lines @@
                     forButtonState:image_button_cell::kHoverStateBackground];
   } else {
     [[newTabButton_ cell] setImage:nil
                     forButtonState:image_button_cell::kDefaultStateBackground];
     [[newTabButton_ cell] setImage:nil
                     forButtonState:image_button_cell::kHoverStateBackground];
   }
 }
 
 @end