Extensions: Grant nuisance and already-implied permissions on update

BUG=603822

Review-Url: https://codereview.chromium.org/1995533002
Cr-Commit-Position: refs/heads/master@{#394511}
diff --git a/chrome/browser/extensions/extension_service.cc b/chrome/browser/extensions/extension_service.cc
index 046574a6..93c7c595 100644
--- a/chrome/browser/extensions/extension_service.cc
+++ b/chrome/browser/extensions/extension_service.cc
@@ -1600,6 +1600,13 @@
             *granted_permissions,
             extension->permissions_data()->active_permissions(),
             extension->GetType());
+
+    // If there was no privilege increase, the extension might still have new
+    // permissions (which either don't generate a warning message, or whose
+    // warning messages are suppressed by existing permissions). Grant the new
+    // permissions.
+    if (!is_privilege_increase)
+      GrantPermissions(extension);
   }
 
   if (is_extension_installed) {