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

ui/accessibility/platform/ax_platform_node_auralinux.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/accessibility/platform/ax_platform_node_auralinux.h"
 
 #include "base/command_line.h"
 #include "base/strings/sys_string_conversions.h"
+#include "base/task_runner.h"
 #include "ui/accessibility/ax_node_data.h"
 #include "ui/accessibility/platform/atk_util_auralinux.h"
 #include "ui/accessibility/platform/ax_platform_node_delegate.h"
 
 //
 // ax_platform_node_auralinux AtkObject definition and implementation.
 //
 
 G_BEGIN_DECLS
 
@@ skipping 261 matching lines @@
   node->Init(delegate);
   return node;
 }
 
 // static
 AXPlatformNode* AXPlatformNodeAuraLinux::application_ = nullptr;
 
 // static
 void AXPlatformNodeAuraLinux::SetApplication(AXPlatformNode* application) {
   application_ = application;
-  AtkUtilAuraLinux::GetInstance();
+}
+
+// static
+void AXPlatformNodeAuraLinux::StaticInitialize(
+    scoped_refptr<base::TaskRunner> init_task_runner) {
+  AtkUtilAuraLinux::GetInstance()->Initialize(init_task_runner);
 }
 
 AtkRole AXPlatformNodeAuraLinux::GetAtkRole() {
   switch (GetData().role) {
     case ui::AX_ROLE_ALERT:
       return ATK_ROLE_ALERT;
     case ui::AX_ROLE_APPLICATION:
       return ATK_ROLE_APPLICATION;
     case ui::AX_ROLE_BUTTON:
       return ATK_ROLE_PUSH_BUTTON;
@@ skipping 85 matching lines @@
 }
 
 void AXPlatformNodeAuraLinux::NotifyAccessibilityEvent(ui::AXEvent event_type) {
 }
 
 int AXPlatformNodeAuraLinux::GetIndexInParent() {
   return 0;
 }
 
 }  // namespace ui