Add the ThirdPartyModules.Uninstallable histogram.

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 5ac1c53e896294c72a492fbd07bdc6d7bb06cc95..03f409238e85da7c326dd713030d7095c8332f29 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -74767,6 +74767,14 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="ThirdPartyModules.Uninstallable" enum="BooleanUninstallable">
+  <owner>pmonette@chromium.org</owner>
+  <summary>
+    Records whether or not a loaded third party module could be uninstalled
+    using the Windows Apps &amp; Features page.
+  </summary>
+</histogram>
+
 <histogram name="ThreadWatcher.ResponseTime" units="ms">
   <owner>rch@chromium.org</owner>
   <summary>
@@ -86157,6 +86165,11 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="1" label="Translated"/>
 </enum>
 
+<enum name="BooleanUninstallable" type="int">
+  <int value="0" label="Not uninstallable"/>
+  <int value="1" label="Uninstallable"/>
+</enum>
+
 <enum name="BooleanUnknown" type="int">
   <int value="0" label="Known"/>
   <int value="1" label="Unknown"/>