Delete JumpListIconsOld and update revised links in every update

chrome/browser/win/jumplist_file_util.h

Index: chrome/browser/win/jumplist_file_util.h
diff --git a/chrome/browser/win/jumplist_file_util.h b/chrome/browser/win/jumplist_file_util.h
index ec618162aa256fcb35c3043ea52cd6b481928141..da37c4f5630c7d4c611e6d4fa9b356ec546883f0 100644
--- a/chrome/browser/win/jumplist_file_util.h
+++ b/chrome/browser/win/jumplist_file_util.h
@@ -5,10 +5,10 @@
 #ifndef CHROME_BROWSER_WIN_JUMPLIST_FILE_UTIL_H_
 #define CHROME_BROWSER_WIN_JUMPLIST_FILE_UTIL_H_
 
-#include "base/files/file_path.h"
+#include "base/files/file_util.h"
 
 // Maximum number of icon files allowed to delete per jumplist update.
-const int kFileDeleteLimit = 100;
+const int kFileDeleteLimit = 60;

[grt (UTC plus 2), 2017/03/27 19:18:48]

why lower this? do metrics indicate that 100 is too much?

[chengx, 2017/03/27 20:26:08]

For users having no trouble in using Chrome, 60 and 100 make no difference. For
users who have already thousands of icons in the folder, the difference between
60 and 100 is that as of 60, it takes less time to delete icons per update, but
more times to delete them all. However, given that it is suspicious base::Delete
has no guarantee that the icons are gone even the function return value is
SUCCESS, reducing the limit from 100 to 60 may give users a litter better
experience. 

 
 // Folder delete status enumeration, used in Delete* methods below.
 // This is used for UMA. Do not delete entries, and keep in sync with
@@ -36,14 +36,15 @@ enum FolderDeleteResult {
   END
 };
 
-// An enumeration indicating if a directory is empty or not.
+// An enumeration indicating if a directory exists or if it is empty or not.
 // This is used for UMA. Do not delete entries, and keep in sync with
 // histograms.xml.
-enum DirectoryEmptyStatus {
+enum DirectoryStatus {
   EMPTY = 0,
   NON_EMPTY,
+  NON_EXIST,
   // Add new items before this one, always keep this one at the end.
-  EMPTY_STATUS_END
+  DIRECTORY_STATUS_END
 };
 
 // This method is similar to base::DeleteFileRecursive in