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

chrome/browser/extensions/favicon_downloader.cc

+// 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.
+
+#include "chrome/browser/extensions/favicon_downloader.h"
+
+#include "base/bind.h"
+#include "chrome/browser/favicon/favicon_tab_helper.h"
+#include "content/public/browser/web_contents.h"
+#include "content/public/common/favicon_url.h"
+#include "third_party/skia/include/core/SkBitmap.h"
+#include "ui/gfx/size.h"
+
+FaviconDownloader::FaviconDownloader(
+  content::WebContents* web_contents,
+  const std::vector<GURL>& extra_favicon_urls,
+  FaviconDownloaderCallback callback)
+  : content::WebContentsObserver(web_contents),
+    got_favicon_urls_(false),
+    extra_favicon_urls_(extra_favicon_urls),
+    callback_(callback),
+    weak_ptr_factory_(this) {
+}
+
+FaviconDownloader::~FaviconDownloader() {
+}
+
+void FaviconDownloader::Start() {
+  // If the candidates aren't loaded, icons will be fetched when
+  // DidUpdateFaviconURL() is called.
+  FetchIcons(extra_favicon_urls_);
+  std::vector<content::FaviconURL> favicon_tab_helper_urls =
+      GetFaviconURLsFromWebContents();
+  if (!favicon_tab_helper_urls.empty()) {

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

Could this ever be empty, but all favicon urls have been retrieved? 

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

No, WebContentsObserver::DidUpdateFaviconURL is only called with a non-empty
vector so favicon_tab_helper->favicon_urls() is only empty if the favicon urls
haven't been retrieved yet. There is a test I added in the latest patch set that
enforces this.

Added a comment below that explains the assumption.

+    got_favicon_urls_ = true;
+    FetchIcons(favicon_tab_helper_urls);
+  }
+}
+
+int FaviconDownloader::DownloadImage(const GURL& url) {
+  return web_contents()->DownloadImage(
+      url,
+      true,  // is_favicon
+      0,     // no max size
+      base::Bind(&FaviconDownloader::DidDownloadFavicon,
+                 weak_ptr_factory_.GetWeakPtr()));
+}
+
+std::vector<content::FaviconURL>
+    FaviconDownloader::GetFaviconURLsFromWebContents() {
+  FaviconTabHelper* favicon_tab_helper =
+      web_contents() ? FaviconTabHelper::FromWebContents(web_contents()) : NULL;
+  return favicon_tab_helper ? favicon_tab_helper->favicon_urls()
+                            : std::vector<content::FaviconURL>();
+}
+
+void FaviconDownloader::FetchIcons(
+    const std::vector<content::FaviconURL>& favicon_urls) {
+  std::vector<GURL> urls;
+  for (std::vector<content::FaviconURL>::const_iterator it =
+           favicon_urls.begin();
+       it != favicon_urls.end(); ++it) {
+    if (it->icon_type != content::FaviconURL::INVALID_ICON)
+      urls.push_back(it->icon_url);
+  }
+  FetchIcons(urls);
+}
+
+void FaviconDownloader::FetchIcons(const std::vector<GURL>& urls) {
+  // Download icons; put their download ids into |in_progress_requests_| and
+  // their urls into |processed_urls_|.
+  for (std::vector<GURL>::const_iterator it = urls.begin();
+       it != urls.end(); ++it) {
+    // Only start the download if the url hasn't been processed before.
+    if (processed_urls_.insert(*it).second)
+      in_progress_requests_.insert(DownloadImage(*it));
+  }
+
+  // If no downloads were initiated, we can proceed directly to running the
+  // callback.
+  if (in_progress_requests_.empty() && got_favicon_urls_)
+    callback_.Run(true, favicon_map_);
+}
+
+void FaviconDownloader::DidDownloadFavicon(
+    int id,
+    int http_status_code,
+    const GURL& image_url,
+    const std::vector<SkBitmap>& bitmaps,
+    const std::vector<gfx::Size>& original_bitmap_sizes) {
+  // Request may have been canceled by DidNavigateMainFrame().
+  if (in_progress_requests_.erase(id) == 0)
+    return;
+
+  favicon_map_[image_url] = bitmaps;
+
+  // Once all requests have been resolved, perform post-download tasks.
+  if (in_progress_requests_.empty() && got_favicon_urls_)
+    callback_.Run(true, favicon_map_);
+}
+
+// content::WebContentsObserver overrides:
+void FaviconDownloader::DidNavigateMainFrame(
+    const content::LoadCommittedDetails& details,
+    const content::FrameNavigateParams& params) {
+  // Clear all pending requests.
+  in_progress_requests_.clear();
+  favicon_map_.clear();
+  callback_.Run(false, favicon_map_);
+}
+
+void FaviconDownloader::DidUpdateFaviconURL(
+    int32 page_id,
+    const std::vector<content::FaviconURL>& candidates) {
+  // Only consider the first candidates we are given. This prevents pages that
+  // change their favicon from spamming us.
+  if (got_favicon_urls_)
+    return;
+
+  got_favicon_urls_ = true;
+  FetchIcons(candidates);
+}