GCM Engine: Split up reg/unreg UNKNOWN_ERROR to improve metrics

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 eb57758267721b6f1b06e9e2b8ccce269c29ba51..257fb2653bc41cc0ddf90370557ba0fdb6b745e1 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -86092,6 +86092,10 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="7" label="HTTP not OK"/>
   <int value="8" label="No response body"/>
   <int value="9" label="Reached maximum number of retries"/>
+  <int value="10" label="Response parsing failed"/>
+  <int value="11" label="Internal server error"/>
+  <int value="12" label="Quota exceeded"/>
+  <int value="13" label="Device has too many registrations"/>
 </enum>
 
 <enum name="GCMResetStoreError" type="int">
@@ -86121,6 +86125,7 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="8" label="HTTP reponse code not OK"/>
   <int value="9" label="Unknown error"/>
   <int value="10" label="Reached maximum number of retries"/>
+  <int value="11" label="Device registration error"/>
 </enum>
 
 <enum name="GCMUpstreamMessageStatus" type="int">