[iOS Reading List] Skip invalid images in distillation.

ios/chrome/browser/reading_list/url_downloader.cc

 // Copyright 2016 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 "ios/chrome/browser/reading_list/url_downloader.h"
 
 #include <string>
 #include <vector>
 
 #include "base/files/file_path.h"
@@ skipping 315 matching lines @@
   bool local_images_found = false;
   for (size_t i = 0; i < images.size(); i++) {
     if (images[i].url.SchemeIs(url::kDataScheme)) {
       // Data URI, the data part of the image is empty, no need to store it.
       continue;
     }
     std::string local_image_name;
     // Mixed content is HTTP images on HTTPS pages.
     bool image_is_mixed_content = distilled_url_.SchemeIsCryptographic() &&
                                   !images[i].url.SchemeIsCryptographic();
-    // Only save images if it is not mixed content.
-    if (!image_is_mixed_content) {
+    // Only save images if it is not mixed content and image data is valid.
+    if (!image_is_mixed_content && images[i].url.is_valid() &&
+        !images[i].data.empty()) {
       if (!SaveImage(url, images[i].url, images[i].data, &local_image_name)) {
         return std::string();
       }
     }
     std::string image_url = net::EscapeForHTML(images[i].url.spec());
     size_t image_url_size = image_url.size();
     size_t pos = mutable_html.find(image_url, 0);
     while (pos != std::string::npos) {
       local_images_found = true;
       mutable_html.replace(pos, image_url_size, local_image_name);
       pos = mutable_html.find(image_url, pos + local_image_name.size());
     }
   }
   if (local_images_found) {
     mutable_html += kDisableImageContextMenuScript;
   }
 
   return mutable_html;
 }
 
 bool URLDownloader::SaveHTMLForURL(std::string html, const GURL& url) {
   if (html.empty()) {
     return false;
   }
   base::FilePath path = reading_list::OfflineURLAbsolutePathFromRelativePath(
       base_directory_,
       reading_list::OfflinePagePath(url, reading_list::OFFLINE_TYPE_HTML));
   return base::WriteFile(path, html.c_str(), html.length()) > 0;
 }