Adds UMA histograms for desktop tab and audio capture through

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 33edbd3bab3aa72b40c95c125f5aae49f6016745..21f8dbe39721443b31d8ee5894743cfe863824be 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -63062,10 +63062,15 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 <enum name="DesktopCaptureCounters" type="int">
   <int value="0" label="Screen capturer created."/>
   <int value="1" label="Window capturer created."/>
-  <int value="2" label="First screen capture call succeeded."/>
-  <int value="3" label="First screen capture call failed."/>
-  <int value="4" label="First window capture call succeeded."/>
-  <int value="5" label="First window capture call failed."/>
+  <int value="2" label="Tab video capturer created."/>
+  <int value="3" label="Tab audio capturer created."/>
+  <int value="4" label="System loopback audio capturer created."/>
+  <int value="5" label="First screen capture call succeeded."/>
+  <int value="6" label="First screen capture call failed."/>
+  <int value="7" label="First window capture call succeeded."/>
+  <int value="8" label="First window capture call failed."/>
+  <int value="9" label="First tab capture call succeeded."/>
+  <int value="10" label="First tab capture call failed."/>
 </enum>
 
 <enum name="DesktopSearchRedirectionInfobarCloseAction" type="int">