Fix a crashing call to GURL::spec() in downloads_api.cc:DownloadItemToJSON()

content/browser/download/download_item_impl.cc

 // 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.
 
 // File method ordering: Methods in this file are in the same order as
 // in download_item_impl.h, with the following exception: The public
 // interface Start is placed in chronological order with the other
 // (private) routines that together define a DownloadItem's state
 // transitions as the download progresses.  See "Download progression
 // cascade" later in this file.
@@ skipping 456 matching lines @@
 
 bool DownloadItemImpl::IsInterrupted() const {
   return InternalToExternalState(state_) == INTERRUPTED;
 }
 
 bool DownloadItemImpl::IsComplete() const {
   return InternalToExternalState(state_) == COMPLETE;
 }
 
 const GURL& DownloadItemImpl::GetURL() const {
-  return url_chain_.empty() ?
-             GURL::EmptyGURL() : url_chain_.back();
+  return url_chain_.empty() ? GURL::EmptyGURL() : url_chain_.back();
 }
 
 const std::vector<GURL>& DownloadItemImpl::GetUrlChain() const {
   return url_chain_;
 }
 
 const GURL& DownloadItemImpl::GetOriginalUrl() const {
-  return url_chain_.front();
+  // Be careful about taking the front() of possibly-empty vectors!
+  // http://crbug.com/190096
+  return url_chain_.empty() ? GURL::EmptyGURL() : url_chain_.front();
 }
 
 const GURL& DownloadItemImpl::GetReferrerUrl() const {
   return referrer_url_;
 }
 
 std::string DownloadItemImpl::GetSuggestedFilename() const {
   return suggested_filename_;
 }
 
@@ skipping 217 matching lines @@
       base::StringPrintf("{ id = %d"
                          " state = %s",
                          download_id_.local(),
                          DebugDownloadStateString(state_));
 
   // Construct a string of the URL chain.
   std::string url_list("<none>");
   if (!url_chain_.empty()) {
     std::vector<GURL>::const_iterator iter = url_chain_.begin();
     std::vector<GURL>::const_iterator last = url_chain_.end();
-    url_list = (*iter).spec();
+    url_list = (*iter).is_valid() ? (*iter).spec() : "<invalid>";
     ++iter;
     for ( ; verbose && (iter != last); ++iter) {
       url_list += " ->\n\t";
       const GURL& next_url = *iter;
-      url_list += next_url.spec();
+      url_list += next_url.is_valid() ? next_url.spec() : "<invalid>";
     }
   }
 
   if (verbose) {
     description += base::StringPrintf(
         " total = %" PRId64
         " received = %" PRId64
         " reason = %s"
         " paused = %c"
         " resume_mode = %s"
@@ skipping 868 matching lines @@
     case RESUME_MODE_USER_CONTINUE:
       return "USER_CONTINUE";
     case RESUME_MODE_USER_RESTART:
       return "USER_RESTART";
   }
   NOTREACHED() << "Unknown resume mode " << mode;
   return "unknown";
 }
 
 }  // namespace content