Don't request missing favicon on every page request.

chrome/browser/favicon/favicon_tab_helper.cc

Index: chrome/browser/favicon/favicon_tab_helper.cc
diff --git a/chrome/browser/favicon/favicon_tab_helper.cc b/chrome/browser/favicon/favicon_tab_helper.cc
index 768e950c9c49e1377436549f26eee8530ec9dd0a..17e4f4a6e2a31fc6990ba25e1e72d1da9baab41d 100644
--- a/chrome/browser/favicon/favicon_tab_helper.cc
+++ b/chrome/browser/favicon/favicon_tab_helper.cc
@@ -135,6 +135,13 @@ NavigationEntry* FaviconTabHelper::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,
@@ -182,6 +189,15 @@ void FaviconTabHelper::DidDownloadFavicon(
     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()) {