Don't request missing favicon on every page request.

chrome/browser/favicon/favicon_tab_helper.cc

 // Copyright (c) 2012 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/favicon/favicon_tab_helper.h"
 
 #include "chrome/browser/favicon/favicon_handler.h"
 #include "chrome/browser/favicon/favicon_service_factory.h"
 #include "chrome/browser/favicon/favicon_util.h"
 #include "chrome/browser/history/history_service.h"
@@ skipping 117 matching lines @@
   }
   service->SetFavicons(entry->GetURL(), favicon.url, history::FAVICON,
                        favicon.image);
 }
 
 NavigationEntry* FaviconTabHelper::GetActiveEntry() {
   return web_contents()->GetController().GetActiveEntry();
 }
 
 int FaviconTabHelper::StartDownload(const GURL& url, int image_size) {
+  FaviconService* favicon_service = FaviconServiceFactory::GetForProfile(
+      profile_->GetOriginalProfile(), Profile::IMPLICIT_ACCESS);
+  if (favicon_service && favicon_service->IsMissingFavicon(url)) {
+    VLOG(1) << "Skip Missing FavIcon: " << url;
+    return 0;
+  }
+
   return web_contents()->DownloadImage(
       url,
       true,
       image_size,
       base::Bind(&FaviconTabHelper::DidDownloadFavicon,base::Unretained(this)));
 }
 
 void FaviconTabHelper::NotifyFaviconUpdated(bool icon_url_changed) {
   content::NotificationService::current()->Notify(
       chrome::NOTIFICATION_FAVICON_UPDATED,
@@ skipping 27 matching lines @@
   favicon_handler_->OnUpdateFaviconURL(page_id, candidates);
   if (touch_icon_handler_.get())
     touch_icon_handler_->OnUpdateFaviconURL(page_id, candidates);
 }
 
 void FaviconTabHelper::DidDownloadFavicon(
     int id,
     const GURL& image_url,
     int requested_size,
     const std::vector<SkBitmap>& bitmaps) {
+
+  if (bitmaps.size() == 0) {

[sky, 2013/05/01 14:00:07]

Under what circumstances should we be doing this? The comments indicate 404, yet
I don't think that empty bitmaps necessary means 404.

[mef, 2013/05/01 15:20:15]

My (possibly incorrect) understanding is that bitmaps vector will be empty if
request have failed for any reason or received data is not a valid image. As far
as I understand to handle 404 specifically this check needs to be done lower,
somewhere inside DownloadImage logic. I've put it here because I didn't want to
clutter DownloadImage with favicon specifics.

On 2013/05/01 14:00:07, sky wrote:

+    VLOG(1) << "Missing Favicon:" << image_url;
+    FaviconService* favicon_service = FaviconServiceFactory::GetForProfile(
+        profile_->GetOriginalProfile(), Profile::IMPLICIT_ACCESS);
+    if (favicon_service)
+      favicon_service->AddMissingFavicon(image_url);
+  }
+
   favicon_handler_->OnDidDownloadFavicon(
       id, image_url, requested_size, bitmaps);
   if (touch_icon_handler_.get()) {
     touch_icon_handler_->OnDidDownloadFavicon(
         id, image_url, requested_size, bitmaps);
   }
 }