[Extensions] More bindings improvements

Explicitly freeze the schema in chrome, pass safe arguments to GetAvailability,
and broaden test access checks.

BUG=603725
BUG=591164

Review URL: https://codereview.chromium.org/1899973002

Cr-Commit-Position: refs/heads/master@{#388353}
diff --git a/extensions/renderer/module_system_test.cc b/extensions/renderer/module_system_test.cc
index b987ee7..e51cc63 100644
--- a/extensions/renderer/module_system_test.cc
+++ b/extensions/renderer/module_system_test.cc
@@ -11,6 +11,7 @@
 #include <utility>
 
 #include "base/callback.h"
+#include "base/command_line.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/lazy_instance.h"
@@ -224,6 +225,7 @@
 
 void ModuleSystemTest::SetUp() {
   env_ = CreateEnvironment();
+  base::CommandLine::ForCurrentProcess()->AppendSwitch("test-type");
 }
 
 void ModuleSystemTest::TearDown() {