Retire some metrics and update file util methods for JumpList

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 12b8f38552a570320bf2fdd9795435ae19855797..b86cebffac48c486dff9913b15277d5fbf9ce66a 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -82313,14 +82313,22 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 
 <histogram name="WinJumplist.DeleteDirectoryContentDuration" units="ms">
   <owner>chengx@chromium.org</owner>
-  <summary>
-    Time spent in DeleteDirectoryContentAndLogResults(). This method is to
-    delete the icon files in JumpListIcons folder.
-  </summary>
+  <summary>Time spent in DeleteDirectoryContentAndLogRuntime().</summary>
+</histogram>
+
+<histogram name="WinJumplist.DeleteDirectoryDuration" units="ms">
+  <obsolete>
+    Obsolete 04/25/2016 as we are no long recording this metric.
+  </obsolete>
+  <owner>chengx@chromium.org</owner>
+  <summary>Time spent in DeleteDirectoryAndLogResults().</summary>
 </histogram>
 
 <histogram name="WinJumplist.DeleteStatusJumpListIcons"
     enum="JumplisticonsDeleteCategory">
+  <obsolete>
+    Obsolete 04/25/2016 as we are no long recording this metric.
+  </obsolete>
   <owner>chengx@chromium.org</owner>
   <summary>
     This metric records the detailed delete result of JumpListIcons directory.
@@ -82329,6 +82337,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 
 <histogram name="WinJumplist.DeleteStatusJumpListIconsOld"
     enum="JumplisticonsDeleteCategory">
+  <obsolete>
+    Obsolete 04/25/2016 as we are no long recording this metric.
+  </obsolete>
   <owner>chengx@chromium.org</owner>
   <summary>
     This metric records the detailed delete result of JumpListIconsOld
@@ -82394,6 +82405,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 
 <histogram name="WinJumplist.DirectoryStatusJumpListIcons"
     enum="JumpListIconsFolderExistOrEmptyCategory">
+  <obsolete>
+    Obsolete 04/25/2016 as we are no long recording this metric.
+  </obsolete>
   <owner>chengx@chromium.org</owner>
   <summary>
         This metric records whether the folder JumpListIcons exists; and if it
@@ -82403,6 +82417,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 
 <histogram name="WinJumplist.DirectoryStatusJumpListIconsOld"
     enum="JumpListIconsFolderExistOrEmptyCategory">
+  <obsolete>
+    Obsolete 04/25/2016 as we are no long recording this metric.
+  </obsolete>
   <owner>chengx@chromium.org</owner>
   <summary>
         This metric records whether the folder JumpListIconsOld exists; and if