Fix enum.xml for QuicInternalErrorLocation to map

QUIC_CHROMIUM_CLIENT_SESSION_CLOSE_SESSION_ON_ERROR

Bug: 815241
Change-Id: I807f9e6938fb6cd02b0d047e31f7056325adb71c
Reviewed-on: https://chromium-review.googlesource.com/951856Reviewed-by: Miriam Gershenson <mgersh@chromium.org>
Commit-Queue: Zhongyi Shi <zhongyi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#541244}

tools/metrics/histograms/enums.xml

@@ -37268,6 +37268,7 @@ Called by update_net_trust_anchors.py.-->
   <int value="18" label="QUIC_STREAM_ACKED_UNSENT_FIN"/>
   <int value="19" label="QUIC_STREAM_ACKED_UNSENT_FIN"/>
   <int value="20" label="QUIC_STREAM_SEQUENCER_BUFFER"/>
+  <int value="21" label="QUIC_CHROMIUM_CLIENT_SESSION_CLOSE_SESSION_ON_ERROR"/>
 </enum>
 
 <enum name="QuickofficeErrorTypes">