MacViews/a11y: Allow accessibility clients to focus and unfocus focusable Views.

ui/accessibility/platform/ax_platform_node_delegate.h

Index: ui/accessibility/platform/ax_platform_node_delegate.h
diff --git a/ui/accessibility/platform/ax_platform_node_delegate.h b/ui/accessibility/platform/ax_platform_node_delegate.h
index 998168a76e7db89110101b25ad1bc67e7b84b817..8569e7ff52d493855f96ecc696b6ccf56cb0d752 100644
--- a/ui/accessibility/platform/ax_platform_node_delegate.h
+++ b/ui/accessibility/platform/ax_platform_node_delegate.h
@@ -94,6 +94,9 @@ class AX_EXPORT AXPlatformNodeDelegate {
   // Whether SetStringValue() is callable, i.e. if the string value is not read
   // only and if the callback exists.
   virtual bool CanSetStringValue() = 0;
+
+  // Focus or unfocus a View, checking if the View is focusable first.
+  virtual bool SetFocused(bool focused) = 0;
 };
 
 }  // namespace ui