[Mac] Remove usage of deprecated FNNotifyByPath().

This moves to using -[NSWorkspace noteFileSystemChanged:], which internally
strips the last path component and calls the deprecated function.

BUG=650794
R=avi@chromium.org

Review-Url: https://codereview.chromium.org/2391573004
Cr-Commit-Position: refs/heads/master@{#422977}

chrome/browser/download/download_status_updater_mac.mm

@@ -242,10 +242,6 @@ void DownloadStatusUpdater::UpdateAppIconDownloadProgress(
     }
 
     // Notify the Finder.
-    NSString* parent_path = [download_path stringByDeletingLastPathComponent];
-    FNNotifyByPath(
-        reinterpret_cast<const UInt8*>([parent_path fileSystemRepresentation]),
-        kFNDirectoryModifiedMessage,
-        kNilOptions);
+    [[NSWorkspace sharedWorkspace] noteFileSystemChanged:download_path];
   }
 }