Remove the majority of the high-traffic Net.Async* histograms.

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 c681c594f1cfa81a87ba5c27743cb80b21b6aa27..adc91c244a4a16d273548380b31224951026dbbf 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -16529,6 +16529,9 @@ Therefore, the affected-histogram name has to have at least one dot in it.
 </histogram>
 
 <histogram name="Net.AsyncResourceHandler_PendingDataCount">
+  <obsolete>
+    Deprecated 03/2015.
+  </obsolete>
   <owner>Please list the metric's owners. Add more owner tags as needed.</owner>
   <summary>
     The count of unacknowledged ResourceMsg_DataReceived messages.  This message
@@ -16537,6 +16540,9 @@ Therefore, the affected-histogram name has to have at least one dot in it.
 </histogram>
 
 <histogram name="Net.AsyncResourceHandler_PendingDataCount_WhenFull">
+  <obsolete>
+    Deprecated 03/2015.
+  </obsolete>
   <owner>Please list the metric's owners. Add more owner tags as needed.</owner>
   <summary>
     The count of unacknowledged ResourceMsg_DataReceived messages at the point
@@ -16554,17 +16560,26 @@ Therefore, the affected-histogram name has to have at least one dot in it.
 </histogram>
 
 <histogram name="Net.AsyncResourceHandler_SharedIOBuffer_Alloc" units="bytes">
+  <obsolete>
+    Deprecated 03/2015.
+  </obsolete>
   <owner>Please list the metric's owners. Add more owner tags as needed.</owner>
   <summary>The size of a SharedIOBuffer allocation.</summary>
 </histogram>
 
 <histogram name="Net.AsyncResourceHandler_SharedIOBuffer_Used" units="bytes">
+  <obsolete>
+    Deprecated 03/2015.
+  </obsolete>
   <owner>Please list the metric's owners. Add more owner tags as needed.</owner>
   <summary>The number of bytes copied into a SharedIOBuffer.</summary>
 </histogram>
 
 <histogram name="Net.AsyncResourceHandler_SharedIOBuffer_UsedPercentage"
     units="percentage">
+  <obsolete>
+    Deprecated 03/2015.
+  </obsolete>
   <owner>Please list the metric's owners. Add more owner tags as needed.</owner>
   <summary>
     The percentage of a SharedIOBuffer allocation that is actually used.