[Mac] On Mavericks or later, use NSWorkspace to open download items.

base/mac/sdk_forward_declarations.h

 // Copyright (c) 2012 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.
 
 // This file contains forward declarations for items in later SDKs than the
 // default one with which Chromium is built (currently 10.6).
 // If you call any function from this header, be sure to check at runtime for
 // respondsToSelector: before calling these functions (else your code will crash
 // on older OS X versions that chrome still supports).
 
@@ skipping 267 matching lines @@
 
 enum {
   NSWindowOcclusionStateVisible = 1UL << 1,
 };
 typedef NSUInteger NSWindowOcclusionState;
 
 @interface NSWindow (MavericksSDK)
 - (NSWindowOcclusionState)occlusionState;
 @end
 
+enum {
+  NSWorkspaceLaunchWithErrorPresentation = 0x00000040
+};
+
 #else  // !MAC_OS_X_VERSION_10_9
 
 typedef enum {
    kCWSecurityModeOpen = 0,
    kCWSecurityModeWEP,
    kCWSecurityModeWPA_PSK,
    kCWSecurityModeWPA2_PSK,
    kCWSecurityModeWPA_Enterprise,
    kCWSecurityModeWPA2_Enterprise,
    kCWSecurityModeWPS,
@@ skipping 19 matching lines @@
 
 @end
 
 BASE_EXPORT extern "C" NSString* const NSUserActivityTypeBrowsingWeb;
 
 BASE_EXPORT extern "C" NSString* const NSAppearanceNameVibrantDark;
 
 #endif  // MAC_OS_X_VERSION_10_10
 
 #endif  // BASE_MAC_SDK_FORWARD_DECLARATIONS_H_