Linux: call xdg-open on downloaded files to open them.

chrome/common/platform_util_mac.mm

 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/common/platform_util.h"
 
 #import <Cocoa/Cocoa.h>
 
 #include "app/l10n_util.h"
 #include "base/file_path.h"
 #include "base/logging.h"
 #include "base/sys_string_conversions.h"
 #include "chrome/browser/cocoa/tab_window_controller.h"
 #include "grit/generated_resources.h"
 
 namespace platform_util {
 
 void ShowItemInFolder(const FilePath& full_path) {
   NSString* path_string = base::SysUTF8ToNSString(full_path.value());
   [[NSWorkspace sharedWorkspace] selectFile:path_string
                    inFileViewerRootedAtPath:nil];
 }
 
+void OpenItem(const FilePath& full_path) {
+  NOTIMPLEMENTED();
+}
+
 gfx::NativeWindow GetTopLevel(gfx::NativeView view) {
   return [view window];
 }
 
 string16 GetWindowTitle(gfx::NativeWindow window) {
   NSString* title = nil;
   if ([[window delegate] isKindOfClass:[TabWindowController class]])
     title = [[window delegate] selectedTabTitle];
   else
     title = [window title];
   // If we don't yet have a title, use "Untitled".
   if (![title length])
     return WideToUTF16(l10n_util::GetString(
         IDS_BROWSER_WINDOW_MAC_TAB_UNTITLED));
 
   return base::SysNSStringToUTF16(title);
 }
 
 bool IsWindowActive(gfx::NativeWindow window) {
   NOTIMPLEMENTED();
   return false;
 }
 
 bool IsVisible(gfx::NativeView view) {
   NOTIMPLEMENTED();
   return true;
 }
 
 }  // namespace platform_util