Provide UI for per-extension enabling/disabling of error collection.

chrome/browser/extensions/api/developer_private/developer_private_api.cc

Index: chrome/browser/extensions/api/developer_private/developer_private_api.cc
diff --git a/chrome/browser/extensions/api/developer_private/developer_private_api.cc b/chrome/browser/extensions/api/developer_private/developer_private_api.cc
index 22954c2dcdfed1c73c8e5a908845135c78f7832c..294beb5673c51a378b3c834d708680fd6fc08a94 100644
--- a/chrome/browser/extensions/api/developer_private/developer_private_api.cc
+++ b/chrome/browser/extensions/api/developer_private/developer_private_api.cc
@@ -389,6 +389,9 @@ DeveloperPrivateGetItemsInfoFunction::CreateItemInfo(const Extension& item,
               info->runtime_errors.push_back(make_linked_ptr(value.release()));
               break;
             }
+            case ExtensionError::NUM_ERROR_TYPES:
+              NOTREACHED();
+              break;
           }
         }
       }