Headless: filter out empty arguments

Users might specify an empty argument by mistake and it gets
then treated as a file path resulting in an unexpected internal page
with unexpected console messages. It probably makes sense to default
to about:blank if no file path was explicitly provided (similar to no args).

Bug: none
Change-Id: Iad93561de8da0249c23c9fbbd23f8fe2b2ba56bf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5155468
Auto-Submit: Alex Rudenko <alexrudenko@chromium.org>
Reviewed-by: Peter Kvitek <kvitekp@chromium.org>
Commit-Queue: Peter Kvitek <kvitekp@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1243333}

headless/app/headless_shell.cc

@@ -119,6 +119,10 @@ void HeadlessShell::OnBrowserStart(HeadlessBrowser* browser) {
   // driven by a debugger.
   base::CommandLine::StringVector args =
       base::CommandLine::ForCurrentProcess()->GetArgs();
+  args.erase(
+      std::remove(args.begin(), args.end(), base::CommandLine::StringType()),
+      args.end());
+
   if (args.empty() && !devtools_enabled) {
     args.push_back(kAboutBlank);
   }