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

ui/views/views_delegate.h

 // Copyright (c) 2012 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.
 
 #ifndef UI_VIEWS_VIEWS_DELEGATE_H_
 #define UI_VIEWS_VIEWS_DELEGATE_H_
 
 #include <string>
 
 #if defined(OS_WIN)
 #include <windows.h>
 #endif
 
 #include "base/strings/string16.h"
 #include "ui/accessibility/ax_enums.h"
 #include "ui/base/ui_base_types.h"
 #include "ui/gfx/native_widget_types.h"
 #include "ui/views/views_export.h"
 #include "ui/views/widget/widget.h"
 
 namespace base {
+class TaskRunner;
 class TimeDelta;
 }
 
 namespace content {
 class WebContents;
 class BrowserContext;
 class SiteInstance;
 }
 
 namespace gfx {
@@ skipping 99 matching lines @@
   // |remove_standard_frame| in InitParams). If |maximized|, this applies to
   // maximized windows; otherwise to restored windows.
   virtual bool WindowManagerProvidesTitleBar(bool maximized);
 
   // Returns the context factory for new windows.
   virtual ui::ContextFactory* GetContextFactory();
 
   // 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
   // the current value, |callback| is subsequently invoked.  If the edges have
   // not changed, |callback| is never run.
   //
   // The return value is a bitmask of AppbarAutohideEdge.
   virtual int GetAppbarAutohideEdges(HMONITOR monitor,
                                      const base::Closure& callback);
 #endif
 
   // The active ViewsDelegate used by the views system.
   static ViewsDelegate* views_delegate;
 
  private:
   scoped_ptr<ViewsTouchEditingControllerFactory> views_tsc_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ViewsDelegate);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_VIEWS_DELEGATE_H_