Update OS version functions for OS X 10.11 El Capitan.

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 4535bdc83c5fadfbb5795d54b934a75d48d68eb9..09d3ff970a808ce8496194b4d6da73df11242281 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -51595,9 +51595,12 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="15" label="Yosemite (10.10), 32-bit (?)"/>
   <int value="16" label="Yosemite (10.10), 64-bit"/>
   <int value="17" label="Yosemite (10.10), 8-bit (?)"/>
-  <int value="18" label="FutureCat (&gt;10.10), 32-bit (?)"/>
-  <int value="19" label="FutureCat (&gt;10.10), 64-bit"/>
-  <int value="20" label="FutureCat (&gt;10.10), 8-bit (?)"/>
+  <int value="18" label="El Capitan (10.11), 32-bit (?)"/>
+  <int value="19" label="El Capitan (10.11), 64-bit"/>
+  <int value="20" label="El Capitan (10.11), 8-bit (?)"/>
+  <int value="21" label="FutureCat (&gt;10.11), 32-bit (?)"/>
+  <int value="22" label="FutureCat (&gt;10.11), 64-bit"/>
+  <int value="23" label="FutureCat (&gt;10.11), 8-bit (?)"/>

[Avi (use Gerrit), 2015/07/15 23:29:01]

CatSixtyFour is an obsolete histogram
(https://codereview.chromium.org/1030253003), so we don't need to update it.

[Andre, 2015/07/16 20:18:39]

Done.

 </enum>
 
 <enum name="CdmPromiseResult" type="int">