SafeBrowsing DownloadProtectionService: only check final URL against whitelist.

chrome/browser/safe_browsing/download_protection_service.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/safe_browsing/download_protection_service.h"
 
 #include "base/bind.h"
 #include "base/compiler_specific.h"
 #include "base/format_macros.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 552 matching lines @@
     }
     OnFileFeatureExtractionDone();
   }
 
   void CheckWhitelists() {
     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
     DownloadCheckResultReason reason = REASON_MAX;
     if (!database_manager_.get()) {
       reason = REASON_SB_DISABLED;
     } else {
-      for (size_t i = 0; i < url_chain_.size(); ++i) {
-        const GURL& url = url_chain_[i];
-        if (url.is_valid() &&
-            database_manager_->MatchDownloadWhitelistUrl(url)) {
-          VLOG(2) << url << " is on the download whitelist.";
-          reason = REASON_WHITELISTED_URL;
-          break;
-        }
-      }
-      if (referrer_url_.is_valid() && reason == REASON_MAX &&
-          database_manager_->MatchDownloadWhitelistUrl(
-              referrer_url_)) {
-        VLOG(2) << "Referrer url " << referrer_url_
-                << " is on the download whitelist.";
-        reason = REASON_WHITELISTED_REFERRER;
+      const GURL& url = url_chain_.back();
+      if (url.is_valid() && database_manager_->MatchDownloadWhitelistUrl(url)) {
+        VLOG(2) << url << " is on the download whitelist.";
+        reason = REASON_WHITELISTED_URL;
       }
       if (reason != REASON_MAX || signature_info_.trusted()) {
         UMA_HISTOGRAM_COUNTS("SBClientDownload.SignedOrWhitelistedDownload", 1);
       }
     }
     if (reason == REASON_MAX && signature_info_.trusted()) {
       for (int i = 0; i < signature_info_.certificate_chain_size(); ++i) {
         if (CertificateChainIsWhitelisted(
                 signature_info_.certificate_chain(i))) {
           reason = REASON_TRUSTED_EXECUTABLE;
@@ skipping 369 matching lines @@
 GURL DownloadProtectionService::GetDownloadRequestUrl() {
   GURL url(kDownloadRequestUrl);
   std::string api_key = google_apis::GetAPIKey();
   if (!api_key.empty())
     url = url.Resolve("?key=" + net::EscapeQueryParamValue(api_key, true));
 
   return url;
 }
 
 }  // namespace safe_browsing