Never connect a port to the same frame

chrome/browser/extensions/extension_messages_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.
 
 #include <stddef.h>
 #include <stdint.h>
 #include <utility>
 
 #include "base/base64.h"
 #include "base/files/file_path.h"
@@ skipping 144 matching lines @@
                                   "page_in_main_frame.html")) << message_;
 }
 
 // Tests that messages with event_urls are only passed to extensions with
 // appropriate permissions.
 IN_PROC_BROWSER_TEST_F(ExtensionApiTest, MessagingEventURL) {
   MessageSender sender;
   ASSERT_TRUE(RunExtensionTest("messaging/event_url")) << message_;
 }
 
+// Tests that messages cannot be received from the same frame.
+IN_PROC_BROWSER_TEST_F(ExtensionApiTest, MessagingBackgroundOnly) {
+  ASSERT_TRUE(RunExtensionTest("messaging/background_only")) << message_;
+}
+
 // Tests connecting from a panel to its extension.
 class PanelMessagingTest : public ExtensionApiTest {
   void SetUpCommandLine(base::CommandLine* command_line) override {
     ExtensionApiTest::SetUpCommandLine(command_line);
     command_line->AppendSwitch(switches::kEnablePanels);
   }
 };
 
 IN_PROC_BROWSER_TEST_F(PanelMessagingTest, MessagingPanel) {
   ASSERT_TRUE(RunExtensionTest("messaging/connect_panel")) << message_;
@@ skipping 1049 matching lines @@
   ui_test_utils::NavigateToURL(browser(), chromium_org_url());
   EXPECT_EQ(COULD_NOT_ESTABLISH_CONNECTION_ERROR,
             CanConnectAndSendMessagesToMainFrame(invalid.get()));
 }
 
 #endif  // !defined(OS_WIN) - http://crbug.com/350517.
 
 }  // namespace
 
 };  // namespace extensions