Don't pass SDCH GetDictionary event for cached responses

net/url_request/url_request_http_job.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 "net/url_request/url_request_http_job.h"
 
 #include "base/base_switches.h"
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
@@ skipping 348 matching lines @@
       // seen, but rather wait until we can justify their usefulness.
       // For now, we will only fetch the first dictionary, which will at least
       // require multiple suggestions before we get additional ones for this
       // site. Eventually we should wait until a dictionary is requested
       // several times
       // before we even download it (so that we don't waste memory or
       // bandwidth).
       if (GetResponseHeaders()->EnumerateHeader(&iter, name, &url_text)) {
         // Resolve suggested URL relative to request url.
         GURL sdch_dictionary_url = request_->url().Resolve(url_text);
-        if (sdch_dictionary_url.is_valid()) {
+        // Don't try to download Dictionary for cached responses. It's either
+        // useless or too late.
+        if (sdch_dictionary_url.is_valid() && !is_cached_content_) {
           rv = sdch_manager->OnGetDictionary(request_->url(),
                                              sdch_dictionary_url);
           if (rv != SDCH_OK) {
             SdchManager::SdchErrorRecovery(rv);
             request_->net_log().AddEvent(
                 NetLog::TYPE_SDCH_DICTIONARY_ERROR,
                 base::Bind(&NetLogSdchDictionaryFetchProblemCallback, rv,
                            sdch_dictionary_url, false));
           }
         }
@@ skipping 1230 matching lines @@
   return override_response_headers_.get() ?
              override_response_headers_.get() :
              transaction_->GetResponseInfo()->headers.get();
 }
 
 void URLRequestHttpJob::NotifyURLRequestDestroyed() {
   awaiting_callback_ = false;
 }
 
 }  // namespace net