Don't request missing favicon on every page request.

content/renderer/fetchers/multi_resolution_image_resource_fetcher.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 "content/renderer/fetchers/multi_resolution_image_resource_fetcher.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebFrame.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "ui/gfx/size.h"
 #include "webkit/glue/image_decoder.h"
 
 using WebKit::WebFrame;
 using WebKit::WebURLRequest;
 using WebKit::WebURLResponse;
 
 namespace content {
 
 MultiResolutionImageResourceFetcher::MultiResolutionImageResourceFetcher(
     const GURL& image_url,
     WebFrame* frame,
     int id,
     WebURLRequest::TargetType target_type,
     const Callback& callback)
     : callback_(callback),
       id_(id),
+      http_status_code_(0),
       image_url_(image_url) {
   fetcher_.reset(new ResourceFetcher(
       image_url, frame, target_type,
       base::Bind(&MultiResolutionImageResourceFetcher::OnURLFetchComplete,
                  base::Unretained(this))));
 }
 
 MultiResolutionImageResourceFetcher::~MultiResolutionImageResourceFetcher() {
   if (!fetcher_->completed())
     fetcher_->Cancel();
 }
 
 void MultiResolutionImageResourceFetcher::OnURLFetchComplete(
     const WebURLResponse& response,
     const std::string& data) {
   std::vector<SkBitmap> bitmaps;
-  if (!response.isNull() && response.httpStatusCode() == 200) {
-    // Request succeeded, try to convert it to an image.
-    bitmaps = webkit_glue::ImageDecoder::DecodeAll(
-        reinterpret_cast<const unsigned char*>(data.data()), data.size());
+  if (!response.isNull()) {
+    http_status_code_ = response.httpStatusCode();
+    if (http_status_code_ == 200) {
+      // Request succeeded, try to convert it to an image.
+      bitmaps = webkit_glue::ImageDecoder::DecodeAll(
+          reinterpret_cast<const unsigned char*>(data.data()), data.size());
+    }
   } // else case:
     // If we get here, it means no image from server or couldn't decode the
     // response as an image. The delegate will see an empty vector.
 
   // Take a reference to the callback as running the callback may lead to our
   // destruction.
   Callback callback = callback_;
   callback.Run(this, bitmaps);
 }
 
 }  // namespace content