Allow requesting Automation tree by tabId

chrome/common/extensions/api/automation_internal.idl

Index: chrome/common/extensions/api/automation_internal.idl
diff --git a/chrome/common/extensions/api/automation_internal.idl b/chrome/common/extensions/api/automation_internal.idl
index c396eb063f3331d7b00b2152b259ec654638d0ea..1b1d721f4c83fe492e88fe424bf6265d53e88549 100644
--- a/chrome/common/extensions/api/automation_internal.idl
+++ b/chrome/common/extensions/api/automation_internal.idl
@@ -83,9 +83,10 @@ namespace automationInternal {
   callback EnableDesktopCallback = void();
 
   interface Functions {
-    // Enable automation of the active tab and retrieves its routing id for use
-    // in future updates.
-    static void enableCurrentTab(EnableTabCallback callback);
+    // Enable automation of the tab with the given id, or the active tab if no
+    // tab id is given, and retrieves its process and routing ids for use in
+    // future updates.
+    static void enableTab(optional long tabId, EnableTabCallback callback);
 
     // Enables desktop automation.
     static void enableDesktop(EnableDesktopCallback callback);