Instrument some of the exit paths likely to suffer hangs.

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 1ff3523031afb90d1fd162dd5a3f24c2209a3499..9f0258e34491ccb5889614b9db281b09d8ff4361 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -35438,6 +35438,71 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="Stability.ExitFunnel.BackgroundOff" units="milliseconds">
+  <owner>siggi@chromium.org</owner>
+  <summary>Temporary instrumentation. See http://crbug.com/412384.</summary>

[Mark P, 2014/12/15 19:01:54]

This is unsatisfactory.

Do none of this histograms have any future use, ever?  Will you remove them
_all_?  I am okay with bad histogram descriptions if they're going to be marked
as obsolete real soon now.  Please create a new bug assigned to you targeting
M-41 (is that where the crashes started appearing and that's where you have to
make any fixes?) to clean up the histogram recording and histograms
descriptions.

+</histogram>
+
+<histogram name="Stability.ExitFunnel.BackgroundOn" units="milliseconds">
+  <owner>siggi@chromium.org</owner>
+  <summary>Temporary instrumentation. See http://crbug.com/412384.</summary>
+</histogram>
+
+<histogram name="Stability.ExitFunnel.BrowserExit" units="milliseconds">
+  <owner>siggi@chromium.org</owner>
+  <summary>Temporary instrumentation. See http://crbug.com/412384.</summary>
+</histogram>
+
+<histogram name="Stability.ExitFunnel.EndSession" units="milliseconds">
+  <owner>siggi@chromium.org</owner>
+  <summary>Temporary instrumentation. See http://crbug.com/412384.</summary>
+</histogram>
+
+<histogram name="Stability.ExitFunnel.ES_CloseApp" units="milliseconds">
+  <owner>siggi@chromium.org</owner>
+  <summary>Temporary instrumentation. See http://crbug.com/412384.</summary>
+</histogram>
+
+<histogram name="Stability.ExitFunnel.ES_Critical" units="milliseconds">
+  <owner>siggi@chromium.org</owner>
+  <summary>Temporary instrumentation. See http://crbug.com/412384.</summary>
+</histogram>
+
+<histogram name="Stability.ExitFunnel.ES_Logoff" units="milliseconds">
+  <owner>siggi@chromium.org</owner>
+  <summary>Temporary instrumentation. See http://crbug.com/412384.</summary>
+</histogram>
+
+<histogram name="Stability.ExitFunnel.ES_Other" units="milliseconds">
+  <owner>siggi@chromium.org</owner>
+  <summary>Temporary instrumentation. See http://crbug.com/412384.</summary>
+</histogram>
+
+<histogram name="Stability.ExitFunnel.KillProcess" units="milliseconds">
+  <owner>siggi@chromium.org</owner>
+  <summary>Temporary instrumentation. See http://crbug.com/412384.</summary>
+</histogram>
+
+<histogram name="Stability.ExitFunnel.LastWindowClose" units="milliseconds">
+  <owner>siggi@chromium.org</owner>
+  <summary>Temporary instrumentation. See http://crbug.com/412384.</summary>
+</histogram>
+
+<histogram name="Stability.ExitFunnel.SessionEnding" units="milliseconds">
+  <owner>siggi@chromium.org</owner>
+  <summary>Temporary instrumentation. See http://crbug.com/412384.</summary>
+</histogram>
+
+<histogram name="Stability.ExitFunnel.TraybarExit" units="milliseconds">
+  <owner>siggi@chromium.org</owner>
+  <summary>Temporary instrumentation. See http://crbug.com/412384.</summary>
+</histogram>
+
+<histogram name="Stability.ExitFunnel.WM_ENDSESSION" units="milliseconds">
+  <owner>siggi@chromium.org</owner>
+  <summary>Temporary instrumentation. See http://crbug.com/412384.</summary>
+</histogram>
+
 <histogram name="Stars.Goog_Related" units="percent">
   <owner>yefim@chromium.org</owner>
   <summary>