Force the channel to be dev for active tab and manfiest unit tests.

chrome/common/extensions/manifest_tests/extension_manifest_test.h

 // 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.
 
 #ifndef CHROME_COMMON_EXTENSIONS_MANIFEST_TESTS_EXTENSION_MANIFEST_TEST_H_
 #define CHROME_COMMON_EXTENSIONS_MANIFEST_TESTS_EXTENSION_MANIFEST_TEST_H_
 
 #include "base/values.h"
 #include "base/memory/scoped_ptr.h"
 #include "chrome/common/extensions/extension.h"
 #include "chrome/common/extensions/extension_manifest_constants.h"
+#include "chrome/common/extensions/features/feature.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace errors = extension_manifest_errors;
 namespace keys = extension_manifest_keys;
 
 class ExtensionManifestTest : public testing::Test {
  public:
   ExtensionManifestTest();
 
  protected:
@@ skipping 106 matching lines @@
 
     Testcase(std::string manifest_filename,
              extensions::Extension::Location location,
              int flags);
   };
 
   void RunTestcases(const Testcase* testcases, size_t num_testcases,
       EXPECT_TYPE type);
 
   bool enable_apps_;
+
+  // Force the manifest tests to run as though it were dev channel, since
+  // several tests rely on manifest features being available that aren't
+  // on stable/beta.
+  //
+  // These objects nest, so if a test wants to explicitly test the behaviour
+  // on stable or beta, declare it inside that test.
+  extensions::Feature::ScopedCurrentChannel current_channel_;
 };
 
 #endif  // CHROME_COMMON_EXTENSIONS_MANIFEST_TESTS_EXTENSION_MANIFEST_TEST_H_