Allow requesting Automation tree by tabId

chrome/common/extensions/api/automation.idl

Index: chrome/common/extensions/api/automation.idl
diff --git a/chrome/common/extensions/api/automation.idl b/chrome/common/extensions/api/automation.idl
index 9dd1072d26b43422ab9d4a534b947d847eb930ee..11de2d1d104d3abc5a14773d8412fb7fa34303d2 100644
--- a/chrome/common/extensions/api/automation.idl
+++ b/chrome/common/extensions/api/automation.idl
@@ -89,12 +89,12 @@
   callback RootCallback = void(AutomationTree tree);
 
   interface Functions {
-    // Get the automation tree for the current tab, enabling automation if
-    // necessary. Returns a tree with a placeholder root node; listen for
-    // the "load_complete" event to get a notification that the tree has fully
-    // loaded (the previous root node reference will stop working at or before
-    // this point).
-    [nocompile] static void getTree(RootCallback callback);
+    // Get the automation tree for the tab with the given tabId, or the current
+    // tab if no tabID is given, enabling automation if necessary. Returns a
+    // tree with a placeholder root node; listen for the "loadComplete" event to
+    // get a notification that the tree has fully loaded (the previous root node
+    // reference will stop working at or before this point).
+    [nocompile] static void getTree(optional long tabId, RootCallback callback);
 
     // Get the automation tree for the desktop.
     [nocompile] static void getDesktop(RootCallback callback);