Tabs API is usable without tabs permission.

chrome/browser/extensions/message_service.cc

Index: chrome/browser/extensions/message_service.cc
diff --git a/chrome/browser/extensions/message_service.cc b/chrome/browser/extensions/message_service.cc
index 8758c13df577ec0dfbe168b1b215a1abc3c2b2fc..e5eb7610281d756f73fcda49cdb1d91655d4e7c3 100644
--- a/chrome/browser/extensions/message_service.cc
+++ b/chrome/browser/extensions/message_service.cc
@@ -219,8 +219,10 @@ void MessageService::OpenChannelToExtension(
   // Include info about the opener's tab (if it was a tab).
   std::string tab_json = "null";
   if (source_contents) {
-    scoped_ptr<DictionaryValue> tab_value(
-        ExtensionTabUtil::CreateTabValue(source_contents));
+    scoped_ptr<DictionaryValue> tab_value(ExtensionTabUtil::CreateTabValue(
+            source_contents,
+            profile->GetExtensionService()->extensions()->GetByID(
+                source_extension_id)));
     base::JSONWriter::Write(tab_value.get(), &tab_json);
   }
 
@@ -271,8 +273,10 @@ void MessageService::OpenChannelToTab(
   // Include info about the opener's tab (if it was a tab).
   std::string tab_json = "null";
   if (source_contents) {
-    scoped_ptr<DictionaryValue> tab_value(
-        ExtensionTabUtil::CreateTabValue(source_contents));
+    scoped_ptr<DictionaryValue> tab_value(ExtensionTabUtil::CreateTabValue(
+            source_contents,
+            profile->GetExtensionService()->extensions()->GetByID(
+                extension_id)));
     base::JSONWriter::Write(tab_value.get(), &tab_json);
   }