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

chrome/browser/extensions/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_EXTENSIONS_FAVICON_DOWNLOADER_H_
+#define CHROME_BROWSER_EXTENSIONS_FAVICON_DOWNLOADER_H_
+
+#include <map>
+#include <set>
+#include <vector>
+
+#include "base/callback.h"
+#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 all favicons for a tab.
+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;
+  // |extra_favicon_urls| allows callers to provide icon urls that aren't
+  // |provided by the renderer (e.g touch icons on non-android environments).
+  FaviconDownloader(content::WebContents* web_contents,
+                    const std::vector<GURL>& extra_favicon_urls,
+                    FaviconDownloaderCallback callback);
+  virtual ~FaviconDownloader();
+
+  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);
+
+  // Queries FaviconTabHelper for the page's current favicon URLs.
+  // This is overridden in testing.
+  virtual std::vector<content::FaviconURL> GetFaviconURLsFromWebContents();
+
+  // Fetches icons for the given urls.
+  // |callback| is run when all downloads complete.

[benwells, 2013/12/12 21:17:57]

Nit: what |callback|?

Update: Oh - the |callback_| field? It's missing the underscore.

[calamity, 2013/12/13 03:11:55]

Done.

+  void FetchIcons(const std::vector<content::FaviconURL>& favicon_urls);
+  void FetchIcons(const std::vector<GURL>& urls);
+
+  // 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;
+
+  // Whether we have received favicons from the renderer.
+  // FaviconURLs are received from GetFaviconURLsFromWebContents() if available.

[benwells, 2013/12/12 21:17:57]

Nit: I'd recommend just the first line of this comment describing what the bool
represents, not how the favicon urls are provided. The details here are probably
just going to get out of date.

[calamity, 2013/12/13 03:11:55]

Done.

+  // Otherwise they are provided when WebContentsObserver::DidUpdateFaviconURL()
+  // is called.
+  bool got_favicon_urls_;
+
+  // URLs that aren't given by WebContentsObserver::DidUpdateFaviconURL() that
+  // should be used for this favicon. This is necessary in order to get touch
+  // icons on non-android environments.
+  std::vector<GURL> extra_favicon_urls_;
+
+  // The icons which were downloaded. Populated by FetchIcons().
+  FaviconMap favicon_map_;
+
+  // Request ids of in-progress requests.
+  std::set<int> in_progress_requests_;
+
+  // Urls for which a download has already been initiated. Used to prevent
+  // duplicate downloads of the same url.
+  std::set<GURL> processed_urls_;
+
+  // Callback to run on favicon download completion.
+  FaviconDownloaderCallback callback_;
+
+  base::WeakPtrFactory<FaviconDownloader> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(FaviconDownloader);
+};
+
+#endif  // CHROME_BROWSER_EXTENSIONS_FAVICON_DOWNLOADER_H_