Merge pull request dotnet/corefx#9089 from vancem/EventSourceIndexFixInMaster

Fix for corefx issue dotnet/corefx#9060 visibility fix for EventSourceIndex method

Commit migrated from https://github.com/dotnet/corefx/commit/f8734467c040960defbefb22b7879e9a1cd0664d

src/libraries/System.Diagnostics.Tracing/ref/System.Diagnostics.Tracing.cs

@@ -121,7 +121,7 @@ public abstract partial class EventListener : System.IDisposable
         public void EnableEvents(System.Diagnostics.Tracing.EventSource eventSource, System.Diagnostics.Tracing.EventLevel level) { }
         public void EnableEvents(System.Diagnostics.Tracing.EventSource eventSource, System.Diagnostics.Tracing.EventLevel level, System.Diagnostics.Tracing.EventKeywords matchAnyKeyword) { }
         public void EnableEvents(System.Diagnostics.Tracing.EventSource eventSource, System.Diagnostics.Tracing.EventLevel level, System.Diagnostics.Tracing.EventKeywords matchAnyKeyword, System.Collections.Generic.IDictionary<string, string> arguments) { }
-        public static int EventSourceIndex(System.Diagnostics.Tracing.EventSource eventSource) { return default(int); }
+        protected static int EventSourceIndex(System.Diagnostics.Tracing.EventSource eventSource) { return default(int); }
         protected internal virtual void OnEventSourceCreated(System.Diagnostics.Tracing.EventSource eventSource) { }
         protected internal abstract void OnEventWritten(System.Diagnostics.Tracing.EventWrittenEventArgs eventData);
     }

src/libraries/System.Diagnostics.Tracing/src/ApiCompatBaseline.net462.txt

-CannotMakeMoreVisible : Visibility of member 'System.Diagnostics.Tracing.EventListener.EventSourceIndex(System.Diagnostics.Tracing.EventSource)' is 'Family' in the implementation but 'Public' in the contract.
-MembersMustExist : Member 'System.Diagnostics.Tracing.EventSource.add_EventCommandExecuted(System.EventHandler<System.Diagnostics.Tracing.EventCommandEventArgs>)' does not exist in the implementation but it does exist in the contract.
-MembersMustExist : Member 'System.Diagnostics.Tracing.EventSource.remove_EventCommandExecuted(System.EventHandler<System.Diagnostics.Tracing.EventCommandEventArgs>)' does not exist in the implementation but it does exist in the contract.
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