Implement manifest icon downloader

chrome/browser/manifest/manifest_icon_downloader.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 CHROME_BROWSER_MANIFEST_MANIFEST_ICON_DOWNLOADER_H_
+#define CHROME_BROWSER_MANIFEST_MANIFEST_ICON_DOWNLOADER_H_
+
+#include "base/basictypes.h"
+#include "base/bind.h"
+#include "base/memory/ref_counted.h"
+#include "content/public/browser/web_contents_observer.h"
+#include "content/public/common/manifest.h"

[mlamouri (slow - plz ping), 2015/08/05 08:20:17]

nit: do you need that include?

[Lalit Maganti, 2015/08/05 14:47:13]

Removed.

+#include "third_party/skia/include/core/SkBitmap.h"
+#include "url/gurl.h"

[mlamouri (slow - plz ping), 2015/08/05 08:20:17]

I think you can forward declare GURL.

[Lalit Maganti, 2015/08/05 14:47:13]

Done.

+
+namespace content {
+class WebContents;
+}  // namespace content
+
+class ManifestIconDownloader
+    : public content::WebContentsObserver {
+ public:
+  typedef base::Callback<void(const SkBitmap&)> Callback;

[mlamouri (slow - plz ping), 2015/08/05 08:20:17]

nit: Callback is too generic of a name, maybe IconFetchCallback or
DownloadCallback?

also, let's be modern and do:
using YourCallbackName = base::Callback<void(const SkBitmap&)>;

[Lalit Maganti, 2015/08/05 14:47:13]

Done.

+
+  explicit ManifestIconDownloader(content::WebContents* web_contents);
+  virtual ~ManifestIconDownloader() {}

[mlamouri (slow - plz ping), 2015/08/05 08:20:17]

s/{}/= default;/

[Lalit Maganti, 2015/08/05 14:47:13]

Done.

+
+  // Downloads the icon located at icon_url. If more than one icon is present
+  // at the URL then it attempts to pick the one closest in size bigger than or

[mlamouri (slow - plz ping), 2015/08/05 08:20:17]

nit: I would say "If the file contains multiple icons" instead of "If more than
one icon is present at the URL"

[Lalit Maganti, 2015/08/05 14:47:13]

Done.

+  // equal to ideal_icon_size_in_dp, taking into account the density of the
+  // device. If a bigger icon is chosen then the icon is scaled down to be equal
+  // to ideal_icon_size_in_dp.

[mlamouri (slow - plz ping), 2015/08/05 08:20:17]

nit: could you document what the return value means?

[Lalit Maganti, 2015/08/05 14:47:13]

Done.

+  bool Download(const GURL& icon_url,
+                int ideal_icon_size_in_dp,
+                const Callback& callback);
+
+ private:
+  // Callback run after an attempt to download the manifest icon has been made.
+  void OnIconFetched(const int ideal_icon_size_in_dp,
+                     const Callback& callback,
+                     int id,
+                     int http_status_code,
+                     const GURL& url,
+                     const std::vector<SkBitmap>& bitmaps,
+                     const std::vector<gfx::Size>& sizes);
+
+  base::WeakPtrFactory<ManifestIconDownloader> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(ManifestIconDownloader);
+};
+
+#endif  // CHROME_BROWSER_MANIFEST_MANIFEST_ICON_DOWNLOADER_H_