Make ExtensionContentSettingsStore refcounted.

chrome/browser/content_settings/host_content_settings_map.cc

Index: chrome/browser/content_settings/host_content_settings_map.cc
diff --git a/chrome/browser/content_settings/host_content_settings_map.cc b/chrome/browser/content_settings/host_content_settings_map.cc
index 0c6bf93a3b46ad8e1d4a4473a0c0fdf92f418c0a..226be160d002918414df87852c5036efef24109d 100644
--- a/chrome/browser/content_settings/host_content_settings_map.cc
+++ b/chrome/browser/content_settings/host_content_settings_map.cc
@@ -106,7 +106,7 @@ HostContentSettingsMap::HostContentSettingsMap(Profile* profile)
     // |extension_service| can be NULL in unit tests.
     content_settings_providers_.push_back(make_linked_ptr(
         new content_settings::ExtensionProvider(
-            profile,
+            this,
             extension_service->GetExtensionContentSettingsStore(),
             is_off_the_record_)));
   }
@@ -522,6 +522,14 @@ bool HostContentSettingsMap::IsDefaultContentSettingManaged(
   return false;
 }
 
+void HostContentSettingsMap::ShutdownOnUIThread() {
+  for (ProviderIterator it = content_settings_providers_.begin();
+       it != content_settings_providers_.end();
+       ++it) {
+    (*it)->ShutdownOnUIThread();
+  }
+}
+
 void HostContentSettingsMap::UnregisterObservers() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   if (!profile_)