Remove unused method

Bug: None
Change-Id: Ic4fc38a5486083030354ad6f2a7fac219380f3dc
Reviewed-on: https://chromium-review.googlesource.com/687396Reviewed-by: David Tseng <dtseng@chromium.org>
Commit-Queue: Aaron Leventhal <aleventhal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#505169}

content/browser/accessibility/browser_accessibility_manager.h

@@ -361,9 +361,6 @@ class CONTENT_EXPORT BrowserAccessibilityManager : public ui::AXTreeDelegate {
       const std::vector<ui::AXTreeDelegate::Change>& changes) override;
 
   BrowserAccessibilityDelegate* delegate() const { return delegate_; }
-  void set_delegate(BrowserAccessibilityDelegate* delegate) {
-    delegate_ = delegate;
-  }
 
   // If this BrowserAccessibilityManager is a child frame or guest frame,
   // return the BrowserAccessibilityManager from the highest ancestor frame