Pass a TaskRunner through ViewsDelegate to put AX init on FILE thread

ui/views/views_delegate.h

Index: ui/views/views_delegate.h
diff --git a/ui/views/views_delegate.h b/ui/views/views_delegate.h
index ea14e7887047e936145986e3fe52f8994c32e53a..bcfb345db128aa50365c3ff679995c2735506db1 100644
--- a/ui/views/views_delegate.h
+++ b/ui/views/views_delegate.h
@@ -19,6 +19,7 @@
 #include "ui/views/widget/widget.h"
 
 namespace base {
+class TaskRunner;
 class TimeDelta;
 }
 
@@ -138,6 +139,10 @@ class VIEWS_EXPORT ViewsDelegate {
   // Returns the user-visible name of the application.
   virtual std::string GetApplicationName();
 
+  // Get a task runner suitable for posting possibly-blocking initialization
+  // tasks.
+  virtual scoped_refptr<base::TaskRunner> GetInitializationTaskRunner();
+
 #if defined(OS_WIN)
   // Starts a query for the appbar autohide edges of the specified monitor and
   // returns the current value.  If the query finds the edges have changed from