Explicitly ShutdownOnUIThread the HostContentSettingsMap when destroying the Profile.

chrome/browser/content_settings/host_content_settings_map.h

Index: chrome/browser/content_settings/host_content_settings_map.h
diff --git a/chrome/browser/content_settings/host_content_settings_map.h b/chrome/browser/content_settings/host_content_settings_map.h
index 63f59b092419bfb2e5d112d413c2511807179556..d993bd563c86b884d253dcaad453ab7835658b6f 100644
--- a/chrome/browser/content_settings/host_content_settings_map.h
+++ b/chrome/browser/content_settings/host_content_settings_map.h
@@ -38,8 +38,7 @@ class Profile;
 
 class HostContentSettingsMap
     : public NotificationObserver,
-      public base::RefCountedThreadSafe<HostContentSettingsMap,
-                                        BrowserThread::DeleteOnUIThread> {
+      public base::RefCountedThreadSafe<HostContentSettingsMap> {
  public:
   typedef Tuple3<ContentSettingsPattern, ContentSetting, std::string>
       PatternSettingSourceTriple;
@@ -194,8 +193,7 @@ class HostContentSettingsMap
                        const NotificationDetails& details);
 
  private:
-  friend struct BrowserThread::DeleteOnThread<BrowserThread::UI>;
-  friend class DeleteTask<HostContentSettingsMap>;
+  friend class base::RefCountedThreadSafe<HostContentSettingsMap>;
 
   virtual ~HostContentSettingsMap();
 
@@ -205,16 +203,13 @@ class HostContentSettingsMap
       ContentSettingsType content_type,
       const std::string& resource_identifier) const;
 
-  void UnregisterObservers();
-
   // Various migration methods (old cookie, popup and per-host data gets
   // migrated to the new format).
-  void MigrateObsoleteCookiePref(PrefService* prefs);
+  void MigrateObsoleteCookiePref();
 
-  // The profile we're associated with.
-  Profile* profile_;
+  // Weak; owned by the Profile.
+  PrefService* prefs_;
 
-  NotificationRegistrar notification_registrar_;
   PrefChangeRegistrar pref_change_registrar_;
 
   // Whether this settings map is for an OTR session.