On uninstall, delete shortcuts first, and then remove directory only if empty.

Previously, ShellUtil::RemoveShortcuts() simply wipes out the entire directory if |location| is SHORTCUT_LOCATION_START_MENU or SHORTCUT_LOCATION_APP_SHORTCUTS, for efficiency. But we're now writing code to migrate shortcuts on the self-destruct flow. In this case, wiping out the directory would destroy our results. Therefore the new logic for deletion of these directories are:
- Use same code to remove Chrome-specific shortcuts (this is what's done for other diretories, e.g., Start Menu).
- If the directory becomes empty, then remove it; otherwise do nothing.

The side effect is that if user creates any non-Chrome shortcuts in these directories, then these shortcuts (and the containing directory) will persist after Chrome uninstall. I think this is a pretty normal behavior.

BUG=235857

Review URL: https://chromiumcodereview.appspot.com/22870004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@217130 0039d316-1c4b-4281-b951-d872f2087c98

chrome/installer/util/shell_util.cc

@@ -1289,8 +1289,10 @@ bool BatchShortcutAction(const ShortcutFilterCallback& shortcut_filter,
   return success;
 }
 
-// Removes folder spsecified by {|location|, |dist|, |level|}.
-bool RemoveShortcutFolder(ShellUtil::ShortcutLocation location,
+// If the folder specified by {|location|, |dist|, |level|} is empty, remove it.
+// Otherwise do nothing. Returns true on success, including the vacuous case
+// where no deletion occurred because the directory is non-empty.
+bool RemoveShortcutFolderIfEmpty(ShellUtil::ShortcutLocation location,
                                  BrowserDistribution* dist,
                                  ShellUtil::ShellChange level) {
 
@@ -1306,7 +1308,8 @@ bool RemoveShortcutFolder(ShellUtil::ShortcutLocation location,
     LOG(WARNING) << "Cannot find path at location " << location;
     return false;
   }
-  if (!base::DeleteFile(shortcut_folder, true)) {
+  if (file_util::IsDirectoryEmpty(shortcut_folder) &&
+      !base::DeleteFile(shortcut_folder, true)) {
     LOG(ERROR) << "Cannot remove folder " << shortcut_folder.value();
     return false;
   }
@@ -2029,8 +2032,13 @@ bool ShellUtil::RemoveShortcuts(ShellUtil::ShortcutLocation location,
 
   switch (location) {
     case SHORTCUT_LOCATION_START_MENU:  // Falls through.
-    case SHORTCUT_LOCATION_APP_SHORTCUTS:
-      return RemoveShortcutFolder(location, dist, level);
+    case SHORTCUT_LOCATION_APP_SHORTCUTS: {
+      bool delete_success =
+          BatchShortcutAction(base::Bind(&ShortcutOpDelete), location,
+                                         dist, level, target_exe);
+      bool rmdir_success = RemoveShortcutFolderIfEmpty(location, dist, level);
+      return delete_success && rmdir_success;
+    }
 
     case SHORTCUT_LOCATION_TASKBAR_PINS:
       return BatchShortcutAction(FilterTargetEq(target_exe).