Split out the extensions gin::Runner implementation into a separate class.

extensions/renderer/script_context_unittest.cc

Index: extensions/renderer/script_context_unittest.cc
diff --git a/extensions/renderer/script_context_unittest.cc b/extensions/renderer/script_context_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..b0a846c6b66dd7ff3465154f9c8c062061dabf58
--- /dev/null
+++ b/extensions/renderer/script_context_unittest.cc
@@ -0,0 +1,24 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "extensions/renderer/module_system_test.h"
+#include "extensions/renderer/script_context.h"
+#include "gin/per_context_data.h"
+#include "gin/runner.h"
+
+namespace extensions {
+
+using ScriptContextTest = ModuleSystemTest;
+
+TEST_F(ScriptContextTest, GinRunnerLifetime) {
+  ExpectNoAssertionsMade();
+  base::WeakPtr<gin::Runner> weak_runner =
+      gin::PerContextData::From(env()->context()->v8_context())
+          ->runner()
+          ->GetWeakPtr();
+  env()->ShutdownModuleSystem();
+  EXPECT_FALSE(weak_runner);
+}
+
+}  // namespace extensions