Extensions: Send the tab id to platform apps.

chrome/renderer/resources/extensions/send_request.js

Index: chrome/renderer/resources/extensions/send_request.js
===================================================================
--- chrome/renderer/resources/extensions/send_request.js	(revision 246091)
+++ chrome/renderer/resources/extensions/send_request.js	(working copy)
@@ -123,6 +123,7 @@
 // - forIOThread: true if this function should be handled on the browser IO
 //   thread.
 // - preserveNullInObjects: true if it is safe for null to be in objects.
+// - senderTabId: the ID of the tab that triggered this request.
 function sendRequest(functionName, args, argSchemas, optArgs) {
   calledSendRequest = true;
   if (!optArgs)
@@ -145,7 +146,8 @@
                         requestId,
                         hasCallback,
                         optArgs.forIOThread,
-                        optArgs.preserveNullInObjects);
+                        optArgs.preserveNullInObjects,
+                        optArgs.senderTabId);
 }
 
 function getCalledSendRequest() {