Add a warning when developing an extension that uses old manifest version.

chrome/common/extensions/extension_unittest.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 "chrome/common/extensions/extension.h"
 
 #include "base/format_macros.h"
 #include "base/file_path.h"
 #include "base/file_util.h"
 #include "base/json/json_file_value_serializer.h"
@@ skipping 171 matching lines @@
   // Test that absolute-looking paths ("/"-prefixed) are pasted correctly.
   EXPECT_EQ(extension->url().spec() + "test.html",
             extension->GetResourceURL("/test.html").spec());
 }
 
 TEST(ExtensionTest, GetAbsolutePathNoError) {
   scoped_refptr<Extension> extension = LoadManifestStrict("absolute_path",
       "absolute.json");
   EXPECT_TRUE(extension.get());
   std::string err;
-  std::vector<std::string> warnings;
+  Extension::InstallWarningVector warnings;
   EXPECT_TRUE(extension_file_util::ValidateExtension(extension.get(),
                                                      &err, &warnings));
   EXPECT_EQ(0U, warnings.size());
 
   EXPECT_EQ(extension->path().AppendASCII("test.html").value(),
             extension->GetResource("test.html").GetFilePath().value());
   EXPECT_EQ(extension->path().AppendASCII("test.js").value(),
             extension->GetResource("test.js").GetFilePath().value());
 }
 
@@ skipping 765 matching lines @@
 }
 
 TEST(ExtensionTest, GetSyncTypeExtensionWithTwoPlugins) {
   scoped_refptr<Extension> extension(
       MakeSyncTestExtension(EXTENSION, GURL(), GURL(),
                             Extension::INTERNAL, 2, FilePath()));
   if (extension)
     EXPECT_EQ(extension->GetSyncType(), Extension::SYNC_TYPE_NONE);
 }
 #endif // !defined(OS_CHROMEOS)