Don't crash DRT if dumpFilenameBeingDragged() is called outside a drag.

content/shell/renderer/test_runner/event_sender.cc

 // Copyright 2014 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 "content/shell/renderer/test_runner/event_sender.h"
 
 #include "base/basictypes.h"
 #include "base/logging.h"
 #include "base/strings/stringprintf.h"
 #include "content/public/common/page_zoom.h"
@@ skipping 1541 matching lines @@
     touch_modifiers_ |= mask;
   else
     touch_modifiers_ &= ~mask;
 }
 
 void EventSender::SetTouchCancelable(bool cancelable) {
   touch_cancelable_ = cancelable;
 }
 
 void EventSender::DumpFilenameBeingDragged() {
+  if (current_drag_data_.isNull())
+    return;
+
   WebString filename;
   WebVector<WebDragData::Item> items = current_drag_data_.items();
   for (size_t i = 0; i < items.size(); ++i) {
     if (items[i].storageType == WebDragData::Item::StorageTypeBinaryData) {
       filename = items[i].title;
       break;
     }
   }
   delegate_->PrintMessage(std::string("Filename being dragged: ") +
                           filename.utf8().data() + "\n");
@@ skipping 765 matching lines @@
 
 bool EventSender::HandleInputEventOnViewOrPopup(const WebInputEvent& event) {
   if (WebPagePopup* popup = view_->pagePopup()) {
     if (!WebInputEvent::isKeyboardEventType(event.type))
       return popup->handleInputEvent(event);
   }
   return view_->handleInputEvent(event);
 }
 
 }  // namespace content