Reject unadvertised encodings

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index ac4e64011ed63046411ed39fe56f03bcdb570fbc..0a256ac64c0d35bd0730c96e32351d7a34ef4d0b 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -103716,6 +103716,16 @@ from previous Chrome versions.
   <int value="5" label="SDCHPossible"/>
   <int value="6" label="Invalid"/>
   <int value="7" label="None"/>
+  <int value="8" label="Rejected">
+    Unlike other values, this one is reported from HttpNetworkTransaction in
+    case when unadvertised, but known encoding appears in
+    &quot;Content-Encoding&quot;.

[Randy Smith (Not in Mondays), 2017/04/05 00:03:32]

nit: Add "... and is thus not comparable with the other values, which are
potentially returned from cached entries".

+  </int>
+  <int value="9" label="Unknown">
+    Reported from URLRequestHttpJob::SetUpSourceStream when unknown encoding
+    appears in &quot;Content-Encoding&quot; header. Despite of being reported in
+    this histogram, event does not cause CONTENT_DECODING_FAILED error.
+  </int>
 </enum>
 
 <enum name="NetInternalsUiFeature" type="int">