Add user facing Code Style Option.

src/Features/CSharp/Portable/UseDefaultLiteral/CSharpUseDefaultLiteralDiagnosticAnalyzer.cs

@@ -53,7 +53,7 @@ private void AnalyzeSyntax(SyntaxNodeAnalysisContext context)
                 return;
             }
 
-            var codeStyleOption = optionSet.GetOption(CSharpCodeStyleOptions.PreferSimpleDefault);
+            var codeStyleOption = optionSet.GetOption(CSharpCodeStyleOptions.PreferDefaultLiteral);
             if (!codeStyleOption.Value)
             {
                 return;

src/VisualStudio/CSharp/Impl/Options/Formatting/StyleViewModel.cs

@@ -425,6 +425,21 @@ public Customer()
 //]
     }}
 }}
+";
+
+        private static readonly string s_preferDefaultLiteral = $@"
+using System.Threading;
+
+class Customer
+{{
+//[
+    // {ServicesVSResources.Prefer_colon}
+    void DoWork(CancellationToken cancellationToken = default) {{ }}
+
+    // {ServicesVSResources.Over_colon}
+    void DoWork(CancellationToken cancellationToken = default(CancellationToken)) {{ }}
+//]
+}}
 ";
 
         private static readonly string s_preferInlinedVariableDeclaration = $@"
@@ -693,6 +708,7 @@ internal StyleViewModel(OptionSet optionSet, IServiceProvider serviceProvider) :
             CodeStyleItems.Add(new BooleanCodeStyleOptionViewModel(CSharpCodeStyleOptions.PreferPatternMatchingOverIsWithCastCheck, CSharpVSResources.Prefer_pattern_matching_over_is_with_cast_check, s_preferPatternMatchingOverIsWithCastCheck, s_preferPatternMatchingOverIsWithCastCheck, this, optionSet, expressionPreferencesGroupTitle));
             CodeStyleItems.Add(new BooleanCodeStyleOptionViewModel(CSharpCodeStyleOptions.PreferPatternMatchingOverAsWithNullCheck, CSharpVSResources.Prefer_pattern_matching_over_as_with_null_check, s_preferPatternMatchingOverAsWithNullCheck, s_preferPatternMatchingOverAsWithNullCheck, this, optionSet, expressionPreferencesGroupTitle));
             CodeStyleItems.Add(new BooleanCodeStyleOptionViewModel(CodeStyleOptions.PreferExplicitTupleNames, ServicesVSResources.Prefer_explicit_tuple_name, s_preferExplicitTupleName, s_preferExplicitTupleName, this, optionSet, expressionPreferencesGroupTitle));
+            CodeStyleItems.Add(new BooleanCodeStyleOptionViewModel(CSharpCodeStyleOptions.PreferDefaultLiteral, ServicesVSResources.Prefer_default_literal, s_preferDefaultLiteral, s_preferDefaultLiteral, this, optionSet, expressionPreferencesGroupTitle));
 
             AddExpressionBodyOptions(optionSet, expressionPreferencesGroupTitle);
 

src/VisualStudio/Core/Def/ServicesVSResources.Designer.cs

@@ -19,7 +19,7 @@ namespace Microsoft.VisualStudio.LanguageServices {
     // class via a tool like ResGen or Visual Studio.
     // To add or remove a member, edit your .ResX file then rerun ResGen
     // with the /str option, or rebuild your VS project.
-    [global::System.CodeDom.Compiler.GeneratedCodeAttribute("System.Resources.Tools.StronglyTypedResourceBuilder", "4.0.0.0")]
+    [global::System.CodeDom.Compiler.GeneratedCodeAttribute("System.Resources.Tools.StronglyTypedResourceBuilder", "15.0.0.0")]
     [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
     [global::System.Runtime.CompilerServices.CompilerGeneratedAttribute()]
     internal class ServicesVSResources {
@@ -1502,6 +1502,15 @@ internal class ServicesVSResources {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Prefer &apos;default&apos; literal.
+        /// </summary>
+        internal static string Prefer_default_literal {
+            get {
+                return ResourceManager.GetString("Prefer_default_literal", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Prefer explicit tuple name.
         /// </summary>

src/VisualStudio/Core/Def/ServicesVSResources.resx

@@ -906,10 +906,13 @@ Additional information: {1}</value>
   <data name="prefer_throwing_properties" xml:space="preserve">
     <value>prefer throwing properties</value>
   </data>
-    <data name="When_generating_properties" xml:space="preserve">
+  <data name="When_generating_properties" xml:space="preserve">
     <value>When generating properties:</value>
-    </data>
+  </data>
   <data name="Options" xml:space="preserve">
     <value>Options</value>
   </data>
+  <data name="Prefer_default_literal" xml:space="preserve">
+    <value>Prefer 'default' literal</value>
+  </data>
 </root>
\ No newline at end of file

src/Workspaces/CSharp/Portable/CodeStyle/CSharpCodeStyleOptions.cs

@@ -134,11 +134,11 @@ internal static class CSharpCodeStyleOptions
                 EditorConfigStorageLocation.ForBoolCodeStyleOption("csharp_prefer_braces"),
                 new RoamingProfileStorageLocation($"TextEditor.CSharp.Specific.{nameof(PreferBraces)}")});
 
-        public static readonly Option<CodeStyleOption<bool>> PreferSimpleDefault = new Option<CodeStyleOption<bool>>(
-            nameof(CodeStyleOptions), nameof(PreferSimpleDefault), defaultValue: CodeStyleOptions.TrueWithSuggestionEnforcement,
+        public static readonly Option<CodeStyleOption<bool>> PreferDefaultLiteral = new Option<CodeStyleOption<bool>>(
+            nameof(CodeStyleOptions), nameof(PreferDefaultLiteral), defaultValue: CodeStyleOptions.TrueWithSuggestionEnforcement,
             storageLocations: new OptionStorageLocation[] {
-                EditorConfigStorageLocation.ForBoolCodeStyleOption("csharp_prefer_simple_default"),
-                new RoamingProfileStorageLocation($"TextEditor.CSharp.Specific.{nameof(PreferSimpleDefault)}")});
+                EditorConfigStorageLocation.ForBoolCodeStyleOption("csharp_prefer_default_literal"),
+                new RoamingProfileStorageLocation($"TextEditor.CSharp.Specific.{nameof(PreferDefaultLiteral)}")});
 
         public static IEnumerable<Option<CodeStyleOption<bool>>> GetCodeStyleOptions()
         {
@@ -149,7 +149,7 @@ public static IEnumerable<Option<CodeStyleOption<bool>>> GetCodeStyleOptions()
             yield return PreferPatternMatchingOverAsWithNullCheck;
             yield return PreferPatternMatchingOverIsWithCastCheck;
             yield return PreferBraces;
-            yield return PreferSimpleDefault;
+            yield return PreferDefaultLiteral;
         }
 
         public static IEnumerable<Option<CodeStyleOption<ExpressionBodyPreference>>> GetExpressionBodyOptions()