Remove unused ui::AXPlatformNode pointer from BrowserAccessibility.

content/browser/accessibility/browser_accessibility.h

Index: content/browser/accessibility/browser_accessibility.h
diff --git a/content/browser/accessibility/browser_accessibility.h b/content/browser/accessibility/browser_accessibility.h
index 5412aba0bbe5d6ea04454aa07a980a98f0f2bb62..3864a64f1d0462ba0b0d65efb14fd04a4a5b830b 100644
--- a/content/browser/accessibility/browser_accessibility.h
+++ b/content/browser/accessibility/browser_accessibility.h
@@ -408,13 +408,6 @@ class CONTENT_EXPORT BrowserAccessibility : public ui::AXPlatformNodeDelegate {
   // A unique ID, since node IDs are frame-local.
   int32_t unique_id_;
 
-  // The platform-specific object that implements the accessibility APIs for
-  // this node. Currently some of the platform-specific code is implemented by
-  // subclasses of BrowserAccessibility and some by |platform_node_|, but
-  // eventually we want all of that code to be in AXPlatformNode.  See
-  // http://crbug.com/703369
-  ui::AXPlatformNode* platform_node_;
-
  private:
   // |GetInnerText| recursively includes all the text from descendants such as
   // text found in any embedded object. In contrast, |GetText| might include a