First round of dead file removal

experimental/visual_studio_plugin/src/NaClVsx.Package/Installation/ProvideMSBuildTargetAttribute.cs

-/***************************************************************************
-
-Copyright (c) Microsoft Corporation. All rights reserved.
-This code is licensed under the Visual Studio SDK license terms.
-THIS CODE IS PROVIDED *AS IS* WITHOUT WARRANTY OF
-ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING ANY
-IMPLIED WARRANTIES OF FITNESS FOR A PARTICULAR
-PURPOSE, MERCHANTABILITY, OR NON-INFRINGEMENT.
-
-***************************************************************************/
-
-using System;
-
-namespace Microsoft.VisualStudio.Shell
-{
-    /// <summary>
-    /// This attribute register a custom .targets files to the list of the
-    /// targets known and trusted by MSBuild.
-    /// 
-    /// The registry entries created are:
-    ///   [%RegistryRoot%\MSBuild\SafeImports]
-    ///                 "TargetsLabel"="PathToTheTargetsFile"
-    /// 
-    /// </summary>
-    [AttributeUsage(AttributeTargets.Class, AllowMultiple = true, Inherited = true)]
-    public sealed class ProvideMSBuildTargetsAttribute : RegistrationAttribute
-    {
-        private const string MSBuildSafeImportsPath = @"MSBuild\SafeImports";
-        private string targetsLabel;
-        private string targetsPath;
-
-        /// <summary>
-        /// Creates a new ProvideMSBuildTargets attribute to register a targets file
-        /// to the list of the MSBuild safe imports.
-        /// </summary>
-        /// <param name="targetsLabel">Label to identify the targets.</param>
-        /// <param name="targetsPath">Full path to the targets file.</param>
-        public ProvideMSBuildTargetsAttribute(string targetsLabel, string targetsPath)
-        {
-            if (string.IsNullOrEmpty(targetsLabel))
-            {
-                throw new ArgumentNullException("targetsLabel");
-            }
-            if (string.IsNullOrEmpty(targetsPath))
-            {
-                throw new ArgumentNullException("targetsPath");
-            }
-            this.targetsLabel = targetsLabel;
-            this.targetsPath = targetsPath;
-        }
-
-        /// <summary>
-        ///     Called to register this attribute with the given context.  The context
-        ///     contains the location where the registration inforomation should be placed.
-        ///     It also contains other information such as the type being registered and path information.
-        /// </summary>
-        public override void Register(RegistrationContext context)
-        {
-            if (null == context) {
-                new ArgumentNullException("context");
-            }
-            using (Key safeImportsKey = context.CreateKey(MSBuildSafeImportsPath))
-            {
-                safeImportsKey.SetValue(targetsLabel, targetsPath);
-            }
-
-        }
-
-        /// <summary>
-        /// Unregister this file extension.
-        /// </summary>
-        /// <param name="context"></param>
-        public override void Unregister(RegistrationContext context)
-        {
-            if (null != context)
-            {
-                context.RemoveValue(MSBuildSafeImportsPath, targetsLabel);
-            }
-        }
-    }
-}