[Cronet] Implement batch read in CronetInputStream

components/cronet/android/cronet_url_request.cc

Index: components/cronet/android/cronet_url_request.cc
diff --git a/components/cronet/android/cronet_url_request.cc b/components/cronet/android/cronet_url_request.cc
index bc7b29fea313a72e6d5a580c8669b23e6f1647d0..04489bfce73fe7c108f2c4ee7517424f609f2fac 100644
--- a/components/cronet/android/cronet_url_request.cc
+++ b/components/cronet/android/cronet_url_request.cc
@@ -285,6 +285,8 @@ static jstring GetHttpStatusText(JNIEnv* env,
   DCHECK(request_adapter->IsOnNetworkThread());
   const net::HttpResponseHeaders* headers =
       request_adapter->GetResponseHeaders();
+  if (headers == NULL)
+    return ConvertUTF8ToJavaString(env, "").Release();
   return ConvertUTF8ToJavaString(env, headers->GetStatusText()).Release();
 }