Collect some histograms about signed binary downloads.

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
 
 #include <deque>
 #include <map>
 #include <set>
 #include <string>
 #include <vector>
 
 #include "base/hash_tables.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
 #include "base/synchronization/lock.h"
 #include "base/task.h"
 #include "base/time.h"
 #include "chrome/browser/safe_browsing/safe_browsing_util.h"
 #include "content/common/notification_observer.h"
 #include "content/common/notification_registrar.h"
 #include "googleurl/src/gurl.h"
 
 class MalwareDetails;
@@ skipping 12 matching lines @@
 }
 
 namespace safe_browsing {
 class ClientSideDetectionService;
 class DownloadProtectionService;
 }
 
 // Construction needs to happen on the main thread.
 class SafeBrowsingService
     : public base::RefCountedThreadSafe<SafeBrowsingService>,
+      public base::SupportsWeakPtr<SafeBrowsingService>,

[mattm, 2011/10/19 18:54:12]

Are you aiming to make SafeBrowsingService not refcounted in the future?  Should
add a comment why this is both refcounted and SupportsWeakPtr.

[Brian Ryner, 2011/10/19 19:20:11]

So, the issue I'm trying to address here is that currently, there's a circular
reference: SafeBrowsingService has a reference to DownloadProtectionService, and
DownloadProtectionService has a reference to SafeBrowsingService.

The cycle can be broken by calling SafeBrowsingService::ShutDown, but that isn't
something that is consistently called in various tests that use
SafeBrowsingSservice.  It seemed like it might be less error-prone to have a
strong reference going in only one direction.

Does that make sense, or do you think there's a better way to address this?

[mattm, 2011/10/19 20:04:10]

Still thinking this through, but I think we could:

Make DownloadProtectionService not refcounted at all, but instead
SupportsWeakPtr.  SafeBrowsingService would own the DownloadProtectionService,
and thus we could be sure that the SBService outlives the DPService.  Any time
we post a task for the DPService we'd use a WeakPtr, and those would be safe
since they would each be created only as needed rather than having a long-lived
one like this that would be accessed on multiple threads.

Does that sound sane?

On 2011/10/19 19:20:11, Brian Ryner wrote:

[mattm, 2011/10/19 20:06:07]

Oh, the one thing I forgot to mention: Since we are sure about the lifetime
being longer, then DownloadProtectionService would hold a bare pointer to
SafeBrowsingService instead of a refptr, breaking the cycle.

On 2011/10/19 20:04:10, mattm wrote:

       public NotificationObserver {
  public:
   class Client;
   // Users of this service implement this interface to be notified
   // asynchronously of the result.
   enum UrlCheckResult {
     SAFE,
     URL_PHISHING,
     URL_MALWARE,
     BINARY_MALWARE_URL,  // Binary url leads to a malware.
@@ skipping 502 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_