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

chrome/browser/ui/views/chrome_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 CHROME_BROWSER_UI_VIEWS_CHROME_VIEWS_DELEGATE_H_
 #define CHROME_BROWSER_UI_VIEWS_CHROME_VIEWS_DELEGATE_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "build/build_config.h"
@@ skipping 31 matching lines @@
   void AddRef() override;
   void ReleaseRef() override;
   void OnBeforeWidgetInit(
       views::Widget::InitParams* params,
       views::internal::NativeWidgetDelegate* delegate) override;
 #if defined(OS_LINUX) && !defined(OS_CHROMEOS)
   bool WindowManagerProvidesTitleBar(bool maximized) override;
 #endif
   ui::ContextFactory* GetContextFactory() override;
   std::string GetApplicationName() override;
+  scoped_refptr<base::TaskRunner> GetInitializationTaskRunner() override;

[sky, 2015/04/24 20:52:28]

GetInitializationTaskRunner is very generic. The task-runner that is returned
likely depends on exactly what the task-runner is going to be used for. I'm
inclined to name this more specifically right now. If we need more we name it
more generically and add an enum. I'm specifically thinking of something like: 
GetTaskRunnerForAccessibilityInitialization.

[dmazzoni, 2015/04/24 21:23:43]

OK, if we want to be really specific, we should specify this is only for Aura
Linux; there's nothing blocking we have to do on other platforms.

Renamed GetTaskRunnerForAuraLinuxAccessibilityInit and ifdefed it to only that
build.

 #if defined(OS_WIN)
   virtual int GetAppbarAutohideEdges(HMONITOR monitor,
                                      const base::Closure& callback) override;
 #endif
 
  private:
 #if defined(OS_WIN)
   typedef std::map<HMONITOR, int> AppbarAutohideEdgeMap;
 
   // Callback on main thread with the edges. |returned_edges| is the value that
@@ skipping 15 matching lines @@
   // GetAutohideEdges().start a new query.
   bool in_autohide_edges_callback_;
 
   base::WeakPtrFactory<ChromeViewsDelegate> weak_factory_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(ChromeViewsDelegate);
 };
 
 #endif  // CHROME_BROWSER_UI_VIEWS_CHROME_VIEWS_DELEGATE_H_