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"
+#include "third_party/skia/include/core/SkBitmap.h"
+#include "url/gurl.h"
+
+namespace content {
+class WebContents;
+}  // namespace content
+
+class ManifestIconDownloader
+    : public content::WebContentsObserver {
+ public:
+  explicit ManifestIconDownloader(content::WebContents* web_contents);
+  virtual ~ManifestIconDownloader() {};
+
+  typedef base::Callback<void(const SkBitmap&)> Callback;

[gone, 2015/07/31 18:09:20]

nit: Move the typedef above the constructor.  Seems cleaner and is the same way
the CancelableTaskTracker and WaitableEventWatcher do it.

[Lalit Maganti, 2015/08/03 08:58:29]

Will do.

+  bool Download(const GURL& icon_url,

[gone, 2015/07/31 18:09:20]

Add documentation.

[Lalit Maganti, 2015/08/03 08:58:29]

Will do.

+                int ideal_icon_size,
+                const Callback& callback);
+
+ private:
+  // Callback run after an attempt to download manifest icon has been made.

[gone, 2015/07/31 18:09:20]

nit: to download the manifest icon

[Lalit Maganti, 2015/08/03 08:58:29]

Will do.

+  void OnIconFetched(const int ideal_icon_size,
+                     const Callback& callback,
+                     int id,
+                     int http_status_code,
+                     const GURL& url,
+                     const std::vector<SkBitmap>& bitmaps,
+                     const std::vector<gfx::Size>& sizes);
+  void ScaleAndCallback(const SkBitmap& image,
+                        const float scaled_ideal_icon_size,
+                        const Callback& callback);
+
+  base::WeakPtrFactory<ManifestIconDownloader> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(ManifestIconDownloader);
+};
+
+#endif  // CHROME_BROWSER_MANIFEST_MANIFEST_ICON_DOWNLOADER_H_