Bug 1334465 - Set mIPCClosed to true before calling SendDeleteSelf in order to avoid race r=bagder

In the previous code, a race condition could cause us to call SendSetPriority() after calling SendDeleteSelf.

For example:
T1: SendDeleteSelf()
T2: if (!mIPCClosed) SendSetPriority()
T1: mIPCClosed = true

MozReview-Commit-ID: 3XOwCaphb2o

--HG--
extra : rebase_source : 609b9d111d97a8e4a60117dd79ecd741725ec611

netwerk/protocol/http/HttpChannelParent.cpp

@@ -2292,8 +2292,8 @@ HttpChannelParent::UpdateAndSerializeSecurityInfo(nsACString& aSerializedSecurit
 bool
 HttpChannelParent::DoSendDeleteSelf()
 {
-  bool rv = SendDeleteSelf();
   mIPCClosed = true;
+  bool rv = SendDeleteSelf();
 
   CleanupBackgroundChannel();