[CodeHealth] Remove used RWHVBase::AccessibilityShowMenu.

This is not used anywhere.

Change-Id: I3a4341cf268c51b5966b9d0b78a3f443ff5047d8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2318711Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Commit-Queue: Mustaq Ahmed <mustaq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#792781}

content/browser/renderer_host/render_widget_host_view_base.cc

@@ -459,11 +459,6 @@ RenderWidgetHostViewBase::CreateBrowserAccessibilityManager(
   return nullptr;
 }
 
-void RenderWidgetHostViewBase::AccessibilityShowMenu(const gfx::Point& point) {
-  if (host())
-    host()->ShowContextMenuAtPoint(point, ui::MENU_SOURCE_NONE);
-}
-
 gfx::AcceleratedWidget
     RenderWidgetHostViewBase::AccessibilityGetAcceleratedWidget() {
   return gfx::kNullAcceleratedWidget;

content/browser/renderer_host/render_widget_host_view_base.h

@@ -250,7 +250,6 @@ class CONTENT_EXPORT RenderWidgetHostViewBase
       BrowserAccessibilityDelegate* delegate,
       bool for_root_frame);
 
-  virtual void AccessibilityShowMenu(const gfx::Point& point);
   virtual gfx::AcceleratedWidget AccessibilityGetAcceleratedWidget();
   virtual gfx::NativeViewAccessible AccessibilityGetNativeViewAccessible();
   virtual gfx::NativeViewAccessible