Use high resolution icons where possible for streamlined hosted app icons.

chrome/browser/favicon/favicon_downloader.h

+// Copyright 2013 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_FAVICON_FAVICON_DOWNLOADER_H_
+#define CHROME_BROWSER_FAVICON_FAVICON_DOWNLOADER_H_
+
+#include <set>
+#include <vector>
+
+#include "base/callback.h"
+#include "base/memory/scoped_ptr.h"

[pkotwicz, 2013/12/02 01:00:57]

You do not need to include scoped_ptr.h

[calamity, 2013/12/03 05:52:15]

Done.

+#include "base/memory/weak_ptr.h"
+#include "content/public/browser/web_contents_observer.h"
+
+class SkBitmap;
+
+namespace content {
+struct FaviconURL;
+}
+
+namespace gfx {
+class Size;
+}
+
+// Class to help download the full-size favicons for a tab.

[pkotwicz, 2013/12/02 01:00:57]

Can you update the class description? The goal of the class is to download all
of the favicons for a tab, not the largest one.

[calamity, 2013/12/03 05:52:15]

Done.

+class FaviconDownloader : public content::WebContentsObserver {
+ public:
+  typedef std::map<GURL, std::vector<SkBitmap> > FaviconMap;
+  typedef base::Callback<void(
+          bool,  /* success */
+          /* A map of icon urls to the bitmaps provided by that url. */
+          const FaviconMap&)>
+      FaviconDownloaderCallback;
+
+  FaviconDownloader(content::WebContents* web_contents,
+                    FaviconDownloaderCallback callback);

[pkotwicz, 2013/12/02 01:00:57]

Can the extra favicon URLs be passed into the constructor? Can you also add a
comment as to why the |extra_favicons| field is necessary. (i.e. because you
want touch icons elsewhere than on Android)

[calamity, 2013/12/03 05:52:15]

Done.

+  virtual ~FaviconDownloader();
+
+  void AddExtraFaviconUrl(const GURL& url);
+
+  void Start();
+
+ private:
+  friend class TestFaviconDownloader;
+
+  // Initiates a download of the image at |url| and returns the download id.
+  // This is overridden in testing.
+  virtual int DownloadImage(const GURL& url);
+
+  // Populates |favicon_url_candidates_| if possible.
+  // This is overridden in testing.

[pkotwicz, 2013/12/02 01:00:57]

How about: "Queries FaviconTabHelper for the page's current favicon URLs."

[calamity, 2013/12/03 05:52:15]

Done.

+  virtual void PopulateFaviconURLsFromWebContents();
+
+  // Fetches icons for |favicon_url_candidates_| and |extra_favicon_urls_|.
+  // |callback| is run when all downloads complete.
+  void FetchIcons();
+
+  // Icon download callback.
+  void DidDownloadFavicon(int id,
+                          int http_status_code,
+                          const GURL& image_url,
+                          const std::vector<SkBitmap>& bitmaps,
+                          const std::vector<gfx::Size>& original_bitmap_sizes);
+
+  // content::WebContentsObserver overrides:
+  virtual void DidNavigateMainFrame(
+      const content::LoadCommittedDetails& details,
+      const content::FrameNavigateParams& params) OVERRIDE;
+  virtual void DidUpdateFaviconURL(
+      int32 page_id,
+      const std::vector<content::FaviconURL>& candidates) OVERRIDE;
+
+  // FaviconURLs for the current web contents.
+  // This is populated when PopulateFaviconURLsFromWebContents() is called if
+  // available. Otherwise it is populated when
+  // WebContentsObserver::DidUpdateFaviconURL() is called.
+  const std::vector<content::FaviconURL>* favicon_url_candidates_;
+
+  // URLs that aren't given by WebContentsObserver::DidUpdateFaviconURL() that
+  // should be used for this favicon.
+  std::vector<GURL> extra_favicon_urls_;
+
+  // The current page's icons. Populated by FetchIcons().
+  FaviconMap favicon_map_;
+
+  // Request ids of in-progress requests.
+  std::set<int> in_progress_requests_;
+
+  // Callback to run on favicon download completion.
+  FaviconDownloaderCallback callback_;
+
+  base::WeakPtrFactory<FaviconDownloader> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(FaviconDownloader);
+};
+
+#endif  // CHROME_BROWSER_FAVICON_FAVICON_DOWNLOADER_H_