Tabs API is usable without tabs permission.

chrome/common/extensions/permissions/permission_set.cc

Index: chrome/common/extensions/permissions/permission_set.cc
diff --git a/chrome/common/extensions/permissions/permission_set.cc b/chrome/common/extensions/permissions/permission_set.cc
index 39b8476580186ccc99fea94504d7c4af427cf20c..65b6f27169b375ccd7a0944a92490369299da1a0 100644
--- a/chrome/common/extensions/permissions/permission_set.cc
+++ b/chrome/common/extensions/permissions/permission_set.cc
@@ -47,6 +47,7 @@ const char* kNonPermissionModuleNames[] = {
   "permissions",
   "runtime",
   "scriptBadge",
+  "tabs",
   "test",
   "types"
 };
@@ -58,10 +59,6 @@ const size_t kNumNonPermissionModuleNames =
 // use with no permissions specified.
 const char* kNonPermissionFunctionNames[] = {
   "management.getPermissionWarningsByManifest",
-  "tabs.create",
-  "tabs.onRemoved",
-  "tabs.remove",
-  "tabs.update",
 };
 const size_t kNumNonPermissionFunctionNames =
     arraysize(kNonPermissionFunctionNames);