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 f166cdfab7cd4afbeed3e75e019eded52dd52c16..301262c35abe914d2f46f8000ee9fa260df94227 100644
--- a/chrome/common/extensions/permissions/permission_set.cc
+++ b/chrome/common/extensions/permissions/permission_set.cc
@@ -46,6 +46,7 @@ const char* kNonPermissionModuleNames[] = {
   "permissions",
   "runtime",
   "scriptBadge",
+  "tabs",
   "test",
   "types"
 };
@@ -63,10 +64,6 @@ const char* kNonPermissionFunctionNames[] = {
   "app.installState",
   "app.runningState",
   "management.getPermissionWarningsByManifest",
-  "tabs.create",
-  "tabs.onRemoved",
-  "tabs.remove",
-  "tabs.update",
 };
 const size_t kNumNonPermissionFunctionNames =
     arraysize(kNonPermissionFunctionNames);