Add test for CHECK exit code behavior.

content/renderer/render_frame_impl.cc

Index: content/renderer/render_frame_impl.cc
diff --git a/content/renderer/render_frame_impl.cc b/content/renderer/render_frame_impl.cc
index 2e9c7d131fbccf9a12eacfe4eaef8db1e9da4f8a..afda05747d424e005138b33c04e90cc079688211 100644
--- a/content/renderer/render_frame_impl.cc
+++ b/content/renderer/render_frame_impl.cc
@@ -547,6 +547,11 @@ void MaybeHandleDebugURL(const GURL& url) {
         << "Intentionally exhausting renderer memory because user navigated to "
         << url.spec();
     ExhaustMemory();
+  } else if (url == kChromeUICheckCrashURL) {
+    LOG(ERROR)
+        << "Intentionally causing CHECK because user navigated to "
+        << url.spec();
+    CHECK(false);
   }
 
 #if defined(ADDRESS_SANITIZER) || defined(SYZYASAN)