make SetReceiveBufferSize and SetSendBufferSize return net error codes (instead of bools)

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 d9fcfa784509e970ab671816f522ef5992c3b335..7b5063287d3491dc4d68f8b717b39b73b26b85cb 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -12892,6 +12892,9 @@ other types of suffix sets.
 </histogram>
 
 <histogram name="Net.SocketReceiveBufferUnchangeable" units="Bytes">
+  <obsolete>
+    Replaced by Net.SocketUnchangeableReceiveBuffer 3/31/2014.
+  </obsolete>
   <owner>jar@chromium.org</owner>
   <summary>
     The size of a socket's receive buffer when the attempt to change it via
@@ -12964,6 +12967,14 @@ other types of suffix sets.
   </summary>
 </histogram>
 
+<histogram name="Net.SocketUnchangeableReceiveBuffer" units="Bytes">
+  <owner>jar@chromium.org</owner>
+  <summary>
+    The size of a socket's receive buffer when the attempt to change it via
+    setsockopt failed.
+  </summary>
+</histogram>
+
 <histogram name="Net.SocketUnchangeableSendBuffer" units="Bytes">
   <owner>jar@chromium.org</owner>
   <summary>