Disable the new avatar menu in a test.

This will make the test not fail once the new avatar menu is enabled by default.

BUG=400667

Review URL: https://codereview.chromium.org/489823003

Cr-Commit-Position: refs/heads/master@{#292126}

chrome/browser/profiles/profile_info_cache_unittest.cc

@@ -639,6 +639,8 @@ TEST_F(ProfileInfoCacheTest, MigrateLegacyProfileNamesWithNewAvatarMenu) {
 
 TEST_F(ProfileInfoCacheTest,
        DontMigrateLegacyProfileNamesWithoutNewAvatarMenu) {
+  switches::DisableNewAvatarMenuForTesting(CommandLine::ForCurrentProcess());
+
   EXPECT_EQ(0U, GetCache()->GetNumberOfProfiles());
 
   base::string16 name_1 = ASCIIToUTF16("Default Profile");