RtcEventLogOutputFile needs to reset file_ whenever the file is not successfully opened

RtcEventLogOutputFile needs to reset file_ whenever the file is not successfully opened. (The destructor DCHECKs that file_ only exists if it's active, so as to help maintain this.)

Bug: webrtc:8111
Change-Id: I9a375a142af821b3c7183032f0b5d4d612dfa6b8
Reviewed-on: https://webrtc-review.googlesource.com/8080
Commit-Queue: Elad Alon <eladalon@webrtc.org>
Reviewed-by: Björn Terelius <terelius@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20229}
diff --git a/logging/rtc_event_log/output/rtc_event_log_output_file.cc b/logging/rtc_event_log/output/rtc_event_log_output_file.cc
index 2f8b81c..2e06a36 100644
--- a/logging/rtc_event_log/output/rtc_event_log_output_file.cc
+++ b/logging/rtc_event_log/output/rtc_event_log_output_file.cc
@@ -55,8 +55,8 @@
     // and needs to be closed.
     if (!rtc::ClosePlatformFile(file)) {
       LOG(LS_ERROR) << "Can't close file.";
-      file_.reset();
     }
+    file_.reset();
     return;
   }