Re-land alexbost's experimental Offscreen Tabs API work.

chrome/browser/extensions/extension_offscreen_tabs_apitest.cc

Index: chrome/browser/extensions/extension_offscreen_tabs_apitest.cc
diff --git a/chrome/browser/extensions/extension_offscreen_tabs_apitest.cc b/chrome/browser/extensions/extension_offscreen_tabs_apitest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..72a4e8eae6ff7d97358d99280224b16350afd452
--- /dev/null
+++ b/chrome/browser/extensions/extension_offscreen_tabs_apitest.cc
@@ -0,0 +1,20 @@
+// 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 "base/command_line.h"
+#include "chrome/browser/extensions/extension_apitest.h"
+#include "chrome/common/chrome_switches.h"
+
+class OffscreenTabsApiTest : public ExtensionApiTest {
+ public:
+  void SetUpCommandLine(CommandLine* command_line) {
+    ExtensionApiTest::SetUpCommandLine(command_line);
+    command_line->AppendSwitch(switches::kEnableExperimentalExtensionApis);
+  }
+};
+
+IN_PROC_BROWSER_TEST_F(OffscreenTabsApiTest, OffscreenTabs) {
+  ASSERT_TRUE(RunExtensionTest("offscreen_tabs")) << message_;
+}
+