Determine test coverage for this case.

content/browser/child_process_security_policy_impl.cc

Index: content/browser/child_process_security_policy_impl.cc
diff --git a/content/browser/child_process_security_policy_impl.cc b/content/browser/child_process_security_policy_impl.cc
index a7b4d8854ed4893e2e40bdd26fda909b90c3f31f..a0238134c588230b224cd461ed8f595ee3d56b76 100644
--- a/content/browser/child_process_security_policy_impl.cc
+++ b/content/browser/child_process_security_policy_impl.cc
@@ -800,6 +800,7 @@ bool ChildProcessSecurityPolicyImpl::HasPermissionsForFileSystemFile(
   // page should not be able to place content in that origin via the filesystem
   // API either.
   if (!CanCommitURL(child_id, filesystem_url.origin())) {
+    CHECK(false);
     UMA_HISTOGRAM_BOOLEAN("FileSystem.OriginFailedCanCommitURL", true);
     return false;
   }