[Cronet] Unregister NetLog observer during shutdown

components/cronet/android/cronet_url_request_context_adapter.h

Index: components/cronet/android/cronet_url_request_context_adapter.h
diff --git a/components/cronet/android/cronet_url_request_context_adapter.h b/components/cronet/android/cronet_url_request_context_adapter.h
index 49c2c76fb78eb9e93cc56af87c41c2ed1be47135..7b764314e714c75fc1ad859bebcb9e472c662234 100644
--- a/components/cronet/android/cronet_url_request_context_adapter.h
+++ b/components/cronet/android/cronet_url_request_context_adapter.h
@@ -161,6 +161,10 @@ class CronetURLRequestContextAdapter
       const base::TimeTicks& timestamp,
       net::NetworkQualityObservationSource source) override;
 
+  // Helper method to stop NetLog logging to file. This can be called on any
+  // thread. This will flush any remaining writes to disk.
+  void StopNetLogHelper();
+
   // Network thread is owned by |this|, but is destroyed from java thread.
   base::Thread* network_thread_;