Add UMA stats for chroemos homedir encryption type

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 456f2a74f31cb810d4be4b8eb043c964e295f932..d662450de4bebd59b3146301191c022018c1e7a2 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -9502,6 +9502,14 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Cryptohome.HomedirEncryptionType" enum="HomedirEncryptionType">
+  <owner>dspaid@chromium.org</owner>
+  <summary>
+    The encryption type used for a user's cryptohome directory.  This is logged
+    each time the cryptohome is mounted.
+  </summary>
+</histogram>
+
 <histogram name="Cryptohome.MigrationToGaiaId"
     enum="CryptohomeMigrationToGaiaId">
   <owner>alemate@chromium.org</owner>
@@ -99907,6 +99915,11 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </int>
 </enum>
 
+<enum name="HomedirEncryptionType" type="int">
+  <int value="1" label="Ecryptfs"/>
+  <int value="2" label="Ext4 Dir Encryption"/>
+</enum>
+
 <enum name="HotwordAvailability" type="int">
   <int value="0" label="Unavailable -- reason may be unknown"/>
   <int value="1" label="Available"/>