Update PDF accessibility when zoom level changes

content/public/renderer/render_accessibility.h

 // Copyright 2016 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 CONTENT_PUBLIC_RENDERER_RENDER_ACCESSIBILITY_H_
 #define CONTENT_PUBLIC_RENDERER_RENDER_ACCESSIBILITY_H_
 
 #include "content/common/content_export.h"
 #include "ui/accessibility/ax_node.h"
 #include "ui/accessibility/ax_tree_data.h"
 #include "ui/accessibility/ax_tree_source.h"
 
 namespace content {
 
 // This interface exposes the accessibility tree for one RenderFrame.
 class CONTENT_EXPORT RenderAccessibility {
  public:
   virtual int GenerateAXID() = 0;
 
   using PdfAXTreeSource =
       ui::AXTreeSource<const ui::AXNode*, ui::AXNodeData, ui::AXTreeData>;
   virtual void SetPdfTreeSource(PdfAXTreeSource* source) = 0;
+  virtual void OnPdfRootNodeUpdated() = 0;
 
  protected:
   ~RenderAccessibility() {}
 
  private:
   // This interface should only be implemented inside content.
   friend class RenderAccessibilityImpl;
   RenderAccessibility() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_RENDERER_RENDER_ACCESSIBILITY_H_