[Mac] Use an AppleEvent to tell the Finder to open downloaded items, rather than NSWorkspace.

base/scoped_aedesc.h

Index: base/scoped_aedesc.h
diff --git a/base/scoped_aedesc.h b/base/scoped_aedesc.h
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+++ b/base/scoped_aedesc.h
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+// Copyright (c) 2010 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.
+
+#ifndef BASE_SCOPED_AEDESC_H_
+#define BASE_SCOPED_AEDESC_H_
+#pragma once
+
+#import <CoreServices/CoreServices.h>
+
+#include "base/basictypes.h"
+
+// The scoped_aedesc is used to scope AppleEvent descriptors.  On creation,
+// it will store a NULL descriptor.  On destruction, it will dispose of the
+// descriptor.
+//
+// This class is parameterized for additional type safety checks.  You can use
+// the generic AEDesc type by not providing a template parameter:
+//  scoped_aedesc<> desc;
+template <typename AEDescType = AEDesc>
+class scoped_aedesc {
+ public:
+  scoped_aedesc() {
+    AECreateDesc(typeNull, NULL, 0, &desc_);
+  }
+
+  ~scoped_aedesc() {
+    AEDisposeDesc(&desc_);
+  }
+
+  // Used for in parameters.
+  operator const AEDescType*() {
+    return &desc_;
+  }
+
+  // Used for out parameters.
+  AEDescType* OutPointer() {
+    return &desc_;
+  }
+
+ private:
+  AEDescType desc_;
+
+  DISALLOW_COPY_AND_ASSIGN(scoped_aedesc);
+};
+
+#endif  // BASE_SCOPED_AEDESC_H_