Revert of Remove Referrer Policy from URLFetcher.

net/url_request/url_fetcher.h

Index: net/url_request/url_fetcher.h
diff --git a/net/url_request/url_fetcher.h b/net/url_request/url_fetcher.h
index 80ff3297d6c6d939afb4d240dfe1697a6275ebe2..a83181953ea4e1bae253cae50c6aeb2c4e92b94f 100644
--- a/net/url_request/url_fetcher.h
+++ b/net/url_request/url_fetcher.h
@@ -171,6 +171,11 @@
   // started.
   virtual void SetReferrer(const std::string& referrer) = 0;
 
+  // The referrer policy to apply when updating the referrer during redirects.
+  // The referrer policy may only be changed before Start() is called.
+  virtual void SetReferrerPolicy(
+      URLRequest::ReferrerPolicy referrer_policy) = 0;
+
   // Set extra headers on the request.  Must be called before the request
   // is started.
   // This replaces the entire extra request headers.