Remove "Login Proxy (prototype)" from the chrome.webstorePrivate whitelist.

R=rockot@chromium.org

Review URL: https://codereview.chromium.org/971793002

Cr-Commit-Position: refs/heads/master@{#318836}

chrome/common/extensions/api/_permission_features.json

@@ -989,8 +989,7 @@
     "extension_types": ["extension", "legacy_packaged_app", "hosted_app"],
     "whitelist": [
       "B44D08FD98F1523ED5837D78D0A606EA9D6206E5",  // Web Store
-      "2653F6F6C39BC6EEBD36A09AFB92A19782FF7EB4",  // Enterprise Web Store
-      "2779FA8B45841D61A37207CCFAC9CB393964FE5B"   // Login Proxy (prototype)
+      "2653F6F6C39BC6EEBD36A09AFB92A19782FF7EB4"   // Enterprise Web Store
     ]
   }
 }