Collect some histograms about signed binary downloads.

chrome/browser/download/chrome_download_manager_delegate.h

Index: chrome/browser/download/chrome_download_manager_delegate.h
===================================================================
--- chrome/browser/download/chrome_download_manager_delegate.h	(revision 106177)
+++ chrome/browser/download/chrome_download_manager_delegate.h	(working copy)
@@ -11,6 +11,7 @@
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/task.h"
+#include "chrome/browser/safe_browsing/download_protection_service.h"
 #include "content/browser/download/download_manager_delegate.h"
 #include "content/common/notification_observer.h"
 #include "content/common/notification_registrar.h"
@@ -134,6 +135,11 @@
   // service.
   void CheckDownloadHashDone(int32 download_id, bool is_dangerous_hash);
 
+  // Callback function after the DownloadProtectionService completes.
+  void CheckClientDownloadDone(
+      DownloadItem* item,
+      safe_browsing::DownloadProtectionService::DownloadCheckResult result);
+
   Profile* profile_;
   scoped_ptr<DownloadPrefs> download_prefs_;
   scoped_ptr<DownloadHistory> download_history_;