Refactor ViewsDelegate singleton

ui/views/accessibility/native_view_accessibility_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/views/accessibility/native_view_accessibility_auralinux.h"
 
 #include <algorithm>
 #include <vector>
 
 #include "base/memory/singleton.h"
@@ skipping 101 matching lines @@
   bool SetStringValue(const base::string16& new_value) override {
     return false;
   }
 
  private:
   friend struct DefaultSingletonTraits<AuraLinuxApplication>;
 
   AuraLinuxApplication()
       : platform_node_(ui::AXPlatformNode::Create(this)) {
     data_.role = ui::AX_ROLE_APPLICATION;
-    if (ViewsDelegate::views_delegate) {
+    if (ViewsDelegate::GetInstance()) {
       data_.AddStringAttribute(
           ui::AX_ATTR_NAME,
-          ViewsDelegate::views_delegate->GetApplicationName());
+          ViewsDelegate::GetInstance()->GetApplicationName());
     }
     ui::AXPlatformNodeAuraLinux::SetApplication(platform_node_);
-    if (ViewsDelegate::views_delegate) {
+    if (ViewsDelegate::GetInstance()) {
       // This should be on the a blocking pool thread so that we can open
       // libatk-bridge.so without blocking this thread.
       scoped_refptr<base::TaskRunner> init_task_runner =
-          ViewsDelegate::views_delegate->GetBlockingPoolTaskRunner();
+          ViewsDelegate::GetInstance()->GetBlockingPoolTaskRunner();
       if (init_task_runner)
         ui::AXPlatformNodeAuraLinux::StaticInitialize(init_task_runner);
     }
   }
 
   ~AuraLinuxApplication() override {
     platform_node_->Destroy();
     platform_node_ = nullptr;
   }
 
@@ skipping 20 matching lines @@
 }
 
 gfx::NativeViewAccessible NativeViewAccessibilityAuraLinux::GetParent() {
   gfx::NativeViewAccessible parent = NativeViewAccessibility::GetParent();
   if (!parent)
     parent = AuraLinuxApplication::GetInstance()->GetNativeViewAccessible();
   return parent;
 }
 
 }  // namespace views