Remove histograms for system IPCs returning NPEs.

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 dd923ab85b0b333f8d161b6b6681f0f3f2687ae7..561f1bcb0b803ac15667cd99b43649d5f32fd816 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -32782,6 +32782,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 
 <histogram name="NCN.getNetInfo1stSuccess"
     enum="BooleanAvoidedNullPointerException">
+  <obsolete>
+    Deprecated 5/2017 for Issue 592131.
+  </obsolete>
   <owner>pauljensen@chromium.org</owner>
   <summary>
     True if the first call to ConnectivityManager.getNetworkInfo(Network) did
@@ -32792,6 +32795,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 
 <histogram name="NCN.getNetInfo2ndSuccess"
     enum="BooleanAvoidedNullPointerException">
+  <obsolete>
+    Deprecated 5/2017 for Issue 592131.
+  </obsolete>
   <owner>pauljensen@chromium.org</owner>
   <summary>
     Recorded after the first call to ConnectivityManager.getNetworkInfo(Network)
@@ -32804,6 +32810,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 
 <histogram name="NCN.getWifiInfo1stSuccess"
     enum="BooleanAvoidedNullPointerException">
+  <obsolete>
+    Deprecated 5/2017 for Issue 592131.
+  </obsolete>
   <owner>pauljensen@chromium.org</owner>
   <summary>
     True if the first call to WifiManager.getConnectionInfo() did not throw
@@ -32814,6 +32823,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 
 <histogram name="NCN.getWifiInfo2ndSuccess"
     enum="BooleanAvoidedNullPointerException">
+  <obsolete>
+    Deprecated 5/2017 for Issue 592131.
+  </obsolete>
   <owner>pauljensen@chromium.org</owner>
   <summary>
     Recorded after the first call to WifiManager.getConnectionInfo() threw a