Enable use_once_callback for //content/common/*.mojom

content/renderer/image_downloader/image_downloader_impl.h

 // 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.
 
 #ifndef CONTENT_RENDERER_IMAGE_DOWNLOADER_IMAGE_DOWNLOADER_IMPL_H_
 #define CONTENT_RENDERER_IMAGE_DOWNLOADER_IMAGE_DOWNLOADER_IMPL_H_
 
 #include "content/common/image_downloader/image_downloader.mojom.h"
 #include "content/renderer/image_downloader/image_downloader_base.h"
 #include "mojo/public/cpp/bindings/binding.h"
@@ skipping 13 matching lines @@
                       mojom::ImageDownloaderRequest request);
 
   // Override ImageDownloaderBase::OnDestruct().
   void OnDestruct() override;
 
   // ImageDownloader implementation.
   void DownloadImage(const GURL& url,
                      bool is_favicon,
                      uint32_t max_bitmap_size,
                      bool bypass_cache,
-                     const DownloadImageCallback& callback) override;
+                     DownloadImageCallback callback) override;
 
   // Called when downloading finishes. All frames in |images| whose size <=
   // |max_image_size| will be returned through |callback|. If all of the frames
   // are larger than |max_image_size|, the smallest frame is resized to
   // |max_image_size| and is the only result. |max_image_size| == 0 is
   // interpreted as no max image size.
   void DidDownloadImage(uint32_t max_bitmap_size,
-                        const DownloadImageCallback& callback,
+                        DownloadImageCallback callback,
                         int32_t http_status_code,
                         const std::vector<SkBitmap>& images);
 
   mojo::Binding<mojom::ImageDownloader> binding_;
 
   DISALLOW_COPY_AND_ASSIGN(ImageDownloaderImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_IMAGE_DOWNLOADER_IMAGE_DOWNLOADER_IMPL_H_