Record shutdown type UMA

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 aa083e83b395db11a79197c856ce191ae347b272..84bd069376d9ce8159d278d88b1975ccd4b87ff5 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -55489,6 +55489,11 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Shutdown.ShutdownType" enum="ShutdownType">
+  <owner>hashimoto@chromium.org</owner>
+  <summary>The type of the last shutdown.</summary>
+</histogram>
+
 <histogram name="Signin" enum="SigninHelperFlow">
   <owner>mlerman@chromium.org</owner>
   <summary>
@@ -94395,6 +94400,13 @@ To add a new entry, add it with any value and run test to compute valid value.
   <int value="6" label="Dark resume failed"/>
 </enum>
 
+<enum name="ShutdownType" type="int">
+  <int value="0" label="Not valid"/>
+  <int value="1" label="Window close"/>
+  <int value="2" label="Browser exit"/>
+  <int value="3" label="End session"/>
+</enum>
+
 <enum name="SideloadUIEvents" type="int">
   <int value="0" label="Extension installed"/>
   <int value="1" label="Extension ignored"/>