Set the Feature's ChannelForTesting to Trunk during extension tests, so that

chrome/browser/extensions/lazy_background_page_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 "base/command_line.h"
 #include "base/file_path.h"
 #include "base/utf_string_conversions.h"
 #include "chrome/browser/bookmarks/bookmark_model.h"
 #include "chrome/browser/extensions/browser_action_test_util.h"
 #include "chrome/browser/extensions/extension_apitest.h"
@@ skipping 53 matching lines @@
 
   Profile* profile_;
   content::NotificationRegistrar registrar_;
   scoped_ptr<LazyBackgroundObserver> original_complete_;
   scoped_ptr<LazyBackgroundObserver> incognito_complete_;
 };
 
 }  // namespace
 
 class LazyBackgroundPageApiTest : public ExtensionApiTest {
-public:
+ public:
   void SetUpCommandLine(CommandLine* command_line) {
     ExtensionApiTest::SetUpCommandLine(command_line);
     command_line->AppendSwitch(switches::kEnableExperimentalExtensionApis);
     // Set shorter delays to prevent test timeouts.
     command_line->AppendSwitchASCII(switches::kEventPageIdleTime, "1");
     command_line->AppendSwitchASCII(switches::kEventPageUnloadingTime, "1");
   }
 
   // Loads the extension, which temporarily starts the lazy background page
   // to dispatch the onInstalled event. We wait until it shuts down again.
@@ skipping 284 matching lines @@
   EXPECT_FALSE(pm->GetBackgroundHostForExtension(last_loaded_extension_id_));
 
   // The browser action has a new title.
   BrowserActionTestUtil browser_action(browser());
   ASSERT_EQ(1, browser_action.NumberOfBrowserActions());
   EXPECT_EQ("Success", browser_action.GetTooltip(0));
 }
 
 // TODO: background page with timer.
 // TODO: background page that interacts with popup.