Use container::back() and container::pop_back() for content.

content/renderer/image_downloader/image_downloader_impl.cc

 // Copyright 2015 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/renderer/image_downloader/image_downloader_impl.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/location.h"
@@ skipping 60 matching lines @@
 // in a box of size |max_image_size|.
 // Sets |original_image_sizes| to the sizes of |images| before resizing.
 void FilterAndResizeImagesForMaximalSize(
     const std::vector<SkBitmap>& unfiltered,
     uint32_t max_image_size,
     std::vector<SkBitmap>* images,
     std::vector<gfx::Size>* original_image_sizes) {
   images->clear();
   original_image_sizes->clear();
 
-  if (!unfiltered.size())
+  if (unfiltered.empty())
     return;
 
   if (max_image_size == 0)
     max_image_size = std::numeric_limits<uint32_t>::max();
 
   const SkBitmap* min_image = NULL;
   uint32_t min_image_size = std::numeric_limits<uint32_t>::max();
   // Filter the images by |max_image_size|, and also identify the smallest image
   // in case all the images are bigger than |max_image_size|.
   for (std::vector<SkBitmap>::const_iterator it = unfiltered.begin();
@@ skipping 127 matching lines @@
     const DownloadImageCallback& callback) {
   callback.Run(http_status_code, mojo::Array<SkBitmap>::From(result_images),
                result_original_image_sizes);
 }
 
 void ImageDownloaderImpl::OnDestruct() {
   delete this;
 }
 
 }  // namespace content