The optional Malware Details also collects HTTP cache information. See design...

chrome/browser/safe_browsing/safe_browsing_service.h

 // Copyright (c) 2011 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.
 //
 // The Safe Browsing service is responsible for downloading anti-phishing and
 // anti-malware tables and checking urls against them.
 
 #ifndef CHROME_BROWSER_SAFE_BROWSING_SAFE_BROWSING_SERVICE_H_
 #define CHROME_BROWSER_SAFE_BROWSING_SAFE_BROWSING_SERVICE_H_
 #pragma once
@@ skipping 221 matching lines @@
 
   // Called on the IO thread to reset the database.
   void ResetDatabase();
 
   // Log the user perceived delay caused by SafeBrowsing. This delay is the time
   // delta starting from when we would have started reading data from the
   // network, and ending when the SafeBrowsing check completes indicating that
   // the current page is 'safe'.
   void LogPauseDelay(base::TimeDelta time);
 
-  // When a safebrowsing blocking page goes away, it calls this method
-  // so the service can serialize and send MalwareDetails.
-  virtual void ReportMalwareDetails(scoped_refptr<MalwareDetails> details);
+  // Called on the IO thread by the MalwareDetails with the serialized
+  // protocol buffer, so the service can send it over.
+  virtual void SendSerializedMalwareDetails(const std::string& serialized);
 
   // Report hits to the unsafe contents (malware, phishing, unsafe download URL)
   // to the server. Can only be called on UI thread.
   void ReportSafeBrowsingHit(const GURL& malicious_url,
                              const GURL& page_url,
                              const GURL& referrer_url,
                              bool is_subresource,
                              UrlCheckResult threat_type);
 
  protected:
@@ skipping 206 matching lines @@
 class SafeBrowsingServiceFactory {
  public:
   SafeBrowsingServiceFactory() { }
   virtual ~SafeBrowsingServiceFactory() { }
   virtual SafeBrowsingService* CreateSafeBrowsingService() = 0;
  private:
   DISALLOW_COPY_AND_ASSIGN(SafeBrowsingServiceFactory);
 };
 
 #endif  // CHROME_BROWSER_SAFE_BROWSING_SAFE_BROWSING_SERVICE_H_