Added flag --extensions-in-action-box to split Action Box and Extensions in it.

chrome/browser/about_flags.cc

Index: chrome/browser/about_flags.cc
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index 17fc69126cc8a19cf80a96d43cc551678e0efa3f..63324eeffda5b02962f7287cb6529985ff6a14f4 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -360,6 +360,13 @@ const Experiment kExperiments[] = {
     SINGLE_VALUE_TYPE(switches::kEnableActionBox),
   },
   {
+    "extensions-in-action-box",
+    IDS_FLAGS_EXTENSIONS_IN_ACTION_BOX_NAME,
+    IDS_FLAGS_EXTENSIONS_IN_ACTION_BOX_DESCRIPTION,
+    kOsAll,
+    SINGLE_VALUE_TYPE(switches::kEnableExtensionsInActionBox),
+  },
+  {
     "script-badges",
     IDS_FLAGS_SCRIPT_BADGES_NAME,
     IDS_FLAGS_SCRIPT_BADGES_DESCRIPTION,