[Extensions] Allow revokable permissions

Add back-end support for revokable extension permissions for optional
permissions, or, if the click-to-script feature is enabled, granted host
permissions.

BUG=532507
[email protected] (micro change in c/b/background/)

Review URL: https://codereview.chromium.org/1327523005

Cr-Commit-Position: refs/heads/master@{#349148}
diff --git a/chrome/browser/extensions/extension_service.cc b/chrome/browser/extensions/extension_service.cc
index 9ccb01e..19cee30 100644
--- a/chrome/browser/extensions/extension_service.cc
+++ b/chrome/browser/extensions/extension_service.cc
@@ -1849,7 +1849,7 @@
     if (!settings->IsPermissionSetAllowed(
             extension.get(),
             extension->permissions_data()->active_permissions())) {
-      extensions::PermissionsUpdater(profile()).RemovePermissions(
+      extensions::PermissionsUpdater(profile()).RemovePermissionsUnsafe(
           extension.get(),
           settings->GetBlockedPermissions(extension.get()).get());
     }