[Extensions] Don't allow gin::Define to be overridden

chrome/browser/extensions/extension_bindings_apitest.cc

 // Copyright (c) 2012 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.
 
 // Contains holistic tests of the bindings infrastructure
 
 #include "chrome/browser/extensions/api/permissions/permissions_api.h"
 #include "chrome/browser/extensions/extension_apitest.h"
 #include "chrome/browser/net/url_request_mock_util.h"
 #include "chrome/browser/ui/browser.h"
@@ skipping 120 matching lines @@
   // See chrome/test/data/extensions/api_test/bindings/override_exports.html.
   std::string result;
   EXPECT_TRUE(content::ExecuteScriptAndExtractString(
       browser()->tab_strip_model()->GetActiveWebContents(),
       "window.domAutomationController.send("
           "document.getElementById('status').textContent.trim());",
       &result));
   EXPECT_EQ("success", result);
 }
 
+IN_PROC_BROWSER_TEST_F(ExtensionBindingsApiTest, NoGinDefineOverriding) {
+  ASSERT_TRUE(embedded_test_server()->InitializeAndWaitUntilReady());
+
+  // We need to create runtime bindings in the web page. An extension that's
+  // externally connectable will do that for us.
+  ASSERT_TRUE(LoadExtension(
+      test_data_dir_.AppendASCII("bindings")
+                    .AppendASCII("externally_connectable_everywhere")));
+
+  ui_test_utils::NavigateToURL(
+      browser(),
+      embedded_test_server()->GetURL(
+          "/extensions/api_test/bindings/override_gin_define.html"));
+  ASSERT_FALSE(
+      browser()->tab_strip_model()->GetActiveWebContents()->IsCrashed());
+
+  // See chrome/test/data/extensions/api_test/bindings/override_gin_define.html.
+  std::string result;
+  EXPECT_TRUE(content::ExecuteScriptAndExtractString(
+      browser()->tab_strip_model()->GetActiveWebContents(),
+      "window.domAutomationController.send("
+          "document.getElementById('status').textContent.trim());",
+      &result));
+  EXPECT_EQ("success", result);
+}
+
 IN_PROC_BROWSER_TEST_F(ExtensionBindingsApiTest, HandlerFunctionTypeChecking) {
   ASSERT_TRUE(embedded_test_server()->InitializeAndWaitUntilReady());
   ui_test_utils::NavigateToURL(
       browser(),
       embedded_test_server()->GetURL(
           "/extensions/api_test/bindings/handler_function_type_checking.html"));
   content::WebContents* web_contents =
       browser()->tab_strip_model()->GetActiveWebContents();
   EXPECT_FALSE(web_contents->IsCrashed());
   // See handler_function_type_checking.html.
   std::string result;
   EXPECT_TRUE(content::ExecuteScriptAndExtractString(
       web_contents,
       "window.domAutomationController.send("
           "document.getElementById('status').textContent.trim());",
       &result));
   EXPECT_EQ("success", result);
 }
 
 }  // namespace
 }  // namespace extensions