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

ui/accessibility/platform/ax_platform_node_auralinux.h

Index: ui/accessibility/platform/ax_platform_node_auralinux.h
diff --git a/ui/accessibility/platform/ax_platform_node_auralinux.h b/ui/accessibility/platform/ax_platform_node_auralinux.h
index 8f86bc71d8d2bdfd9d377e3a064dc8a31a56f99a..7f70f84f22ecc0f2177e54e2e6edce3369409b67 100644
--- a/ui/accessibility/platform/ax_platform_node_auralinux.h
+++ b/ui/accessibility/platform/ax_platform_node_auralinux.h
@@ -7,9 +7,14 @@
 
 #include <atk/atk.h>
 
+#include "base/memory/ref_counted.h"
 #include "ui/accessibility/ax_export.h"
 #include "ui/accessibility/platform/ax_platform_node_base.h"
 
+namespace base {
+class TaskRunner;
+}
+
 namespace ui {
 
 // Implements accessibility on Aura Linux using ATK.
@@ -22,6 +27,10 @@ class AXPlatformNodeAuraLinux : public AXPlatformNodeBase {
   AX_EXPORT static void SetApplication(AXPlatformNode* application);
   static AXPlatformNode* application() { return application_; }
 
+  // Do static initialization using the given task runner for file operations.
+  AX_EXPORT static void StaticInitialize(
+      scoped_refptr<base::TaskRunner> init_task_runner);
+
   AtkRole GetAtkRole();
   void GetAtkState(AtkStateSet* state_set);
   void GetAtkRelations(AtkRelationSet* atk_relation_set);