Log aggregated abort metrics when histograms are uploaded

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 6a23d3b6f868c5b94f614a9351600babdd86877b..2882e398cae7c55ed10d7d63d73510f7c086808c 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -24931,6 +24931,22 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Net.ErrAborted.CountPerUpload" units="counts">

[Ilya Sherman, 2016/03/16 22:33:41]

nit: I'd either write something like units="aborts", or just omit the units
entirely.

[Charlie Harrison, 2016/03/17 14:03:20]

Changed to units="aborts"

+  <owner>csharrison@chromium.org</owner>
+  <summary>
+    The count of the ABORTED bucket in Net.ErrorCodesForMainFrame3 at the time
+    histograms are being uploaded.
+  </summary>
+</histogram>
+
+<histogram name="Net.ErrAborted.ProportionPerUpload" units="%">
+  <owner>csharrison@chromium.org</owner>
+  <summary>
+    The bucket proportion of the ABORTED bucket in Net.ErrorCodesForMainFrame3
+    at the time histograms are being uploaded.
+  </summary>
+</histogram>
+
 <histogram name="Net.ErrAborted.ReceivedBytes" units="bytes">
   <owner>csharrison@chromium.org</owner>
   <summary>