Media Remoting: Draw remoting interstitial on poster image.

content/renderer/image_downloader/single_image_downloader.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/single_image_downloader.h"
+
+#include "base/bind.h"
+#include "base/logging.h"
+
+namespace content {
+
+// Static
+void SingleImageDownloader::DownloadImage(
+    base::WeakPtr<RenderFrame> render_frame,
+    const GURL& url,
+    const DownloadImageCallback& cb) {
+  DCHECK(!cb.is_null());
+  if (!render_frame) {
+    cb.Run(SkBitmap());
+    return;
+  }
+
+  std::unique_ptr<ImageDownloaderBase> image_downloader(
+      new ImageDownloaderBase(render_frame.get()));
+  ImageDownloaderBase* image_downloader_ptr = image_downloader.get();
+  image_downloader_ptr->DownloadImage(
+      url, false, false, base::Bind(&SingleImageDownloader::DidDownloadImage,
+                                    base::Passed(&image_downloader), cb));
+}
+
+// Static
+void SingleImageDownloader::DidDownloadImage(
+    std::unique_ptr<ImageDownloaderBase> image_downloader,

[nasko, 2017/01/04 17:45:33]

nit: Maybe put a comment as to why image_download is unused. Seem we pass it in
as unique_ptr to keep it alive, but it might not be obvious.

[xjz, 2017/01/04 18:37:58]

Done. Yes, this is to keep it alive while downloading and destroy it after
downloading finishes. Added comments in header file.

+    const DownloadImageCallback& callback,
+    int http_status_code,
+    const std::vector<SkBitmap>& images) {
+  DCHECK(!callback.is_null());
+  callback.Run(images.empty() ? SkBitmap() : images[0]);
+}
+
+}  // namespace content