Bug fix: handle type=crashpad-handler (#2449)

I was seeing instances of the subprocess being spawned this way when running the CefSharp.Wpf.Example project. Debugging showed me that no such argument was being passed to the process. This PR works around the issue by opting out from getting the parent process ID for such processes.

Author: perlun

CefSharp.BrowserSubprocess/Program.cs

@@ -4,6 +4,7 @@
 
 using System;
 using System.Diagnostics;
+using System.Linq;
 using System.Threading.Tasks;
 using CefSharp.Internals;
 
@@ -19,13 +20,21 @@ public static int Main(string[] args)
 
             int result;
             var type = args.GetArgumentValue(CefSharpArguments.SubProcessTypeArgument);
-            var parentProcessId = int.Parse(args.GetArgumentValue(CefSharpArguments.HostProcessIdArgument));
-            if (args.HasArgument(CefSharpArguments.ExitIfParentProcessClosed))
+
+            var parentProcessId = -1;
+
+            // The Crashpad Handler doesn't have any HostProcessIdArgument, so we must not try to
+            // parse it lest we want an ArgumentNullException.
+            if (type != "crashpad-handler")
             {
-                Task.Factory.StartNew(() => AwaitParentProcessExit(parentProcessId), TaskCreationOptions.LongRunning);
+                parentProcessId = int.Parse(args.GetArgumentValue(CefSharpArguments.HostProcessIdArgument));
+                if (args.HasArgument(CefSharpArguments.ExitIfParentProcessClosed))
+                {
+                    Task.Factory.StartNew(() => AwaitParentProcessExit(parentProcessId), TaskCreationOptions.LongRunning);
+                }
             }
 
-            //Use our custom subProcess provides features like EvaluateJavascript
+            // Use our custom subProcess provides features like EvaluateJavascript
             if (type == "renderer")
             {
                 var wcfEnabled = args.HasArgument(CefSharpArguments.WcfEnabledArgument);