Add method getAllHeaders to HttpUrlRequest.

components/cronet/android/url_request_peer.cc

Index: components/cronet/android/url_request_peer.cc
diff --git a/components/cronet/android/url_request_peer.cc b/components/cronet/android/url_request_peer.cc
index 4c811941f723457a7fa1f60ca9430fe648f763e9..37385cfab871deb427539d1783b9cac585b6eaab 100644
--- a/components/cronet/android/url_request_peer.cc
+++ b/components/cronet/android/url_request_peer.cc
@@ -67,6 +67,13 @@ std::string URLRequestPeer::GetHeader(const std::string &name) const {
   return value;
 }
 
+net::HttpResponseHeaders* URLRequestPeer::GetResponseHeaders() const {
+  if (url_request_ == NULL) {
+    return NULL;
+  }
+  return url_request_->response_headers();
+}
+
 void URLRequestPeer::Start() {
   context_->GetNetworkTaskRunner()->PostTask(
       FROM_HERE,