Clear DNS cache and passive log collected on incognito close.

chrome/browser/io_thread.h

Index: chrome/browser/io_thread.h
===================================================================
--- chrome/browser/io_thread.h	(revision 112998)
+++ chrome/browser/io_thread.h	(working copy)
@@ -106,6 +106,9 @@
 
   ChromeNetLog* net_log();
 
+  // Handles changing to On The Record mode, discarding confidential data.
+  void ChangedToOnTheRecord();
+
   // Returns a getter for the URLRequestContext.  Only called on the UI thread.
   net::URLRequestContextGetter* system_url_request_context_getter();
 
@@ -143,6 +146,8 @@
   // Returns an SSLConfigService instance.
   net::SSLConfigService* GetSSLConfigService();
 
+  void ChangedToOnTheRecordOnIOThread();
+
   // The NetLog is owned by the browser process, to allow logging from other
   // threads during shutdown, but is used most frequently on the IOThread.
   ChromeNetLog* net_log_;