headless: Fix two issues that are making the bot red

headless/lib/headless_browser_browsertest.cc

Index: headless/lib/headless_browser_browsertest.cc
diff --git a/headless/lib/headless_browser_browsertest.cc b/headless/lib/headless_browser_browsertest.cc
index bd28321b2d0b73a8426840294907568479834366..77796ffe34978858f4a454273b862d446461734b 100644
--- a/headless/lib/headless_browser_browsertest.cc
+++ b/headless/lib/headless_browser_browsertest.cc
@@ -8,6 +8,7 @@
 #include "base/files/file_util.h"
 #include "base/memory/ptr_util.h"
 #include "base/strings/stringprintf.h"
+#include "base/threading/thread_restrictions.h"
 #include "content/public/test/browser_test.h"
 #include "headless/public/domains/network.h"
 #include "headless/public/domains/page.h"
@@ -603,6 +604,7 @@ IN_PROC_BROWSER_TEST_F(HeadlessBrowserTest, SetCookiesWithDevTools) {
 #define MAYBE_RendererCommandPrefixTest DISABLED_RendererCommandPrefixTest
 #endif  // defined(OS_POSIX)
 IN_PROC_BROWSER_TEST_F(HeadlessBrowserTest, MAYBE_RendererCommandPrefixTest) {
+  base::ThreadRestrictions::SetIOAllowed(true);
   base::FilePath launcher_stamp;
   base::CreateTemporaryFile(&launcher_stamp);