Add hack so VoiceOver speaks updates to injected live regions.

content/browser/accessibility/browser_accessibility_manager.h

Index: content/browser/accessibility/browser_accessibility_manager.h
diff --git a/content/browser/accessibility/browser_accessibility_manager.h b/content/browser/accessibility/browser_accessibility_manager.h
index 932a435bd7adb9168fa2fc5e8379118afbd50ebb..5d3349a7d2cfb39f101e6de4f891aa414dda8b73 100644
--- a/content/browser/accessibility/browser_accessibility_manager.h
+++ b/content/browser/accessibility/browser_accessibility_manager.h
@@ -188,6 +188,9 @@ class CONTENT_EXPORT BrowserAccessibilityManager : public ui::AXTreeDelegate {
       BrowserAccessibilityDelegate* delegate,
       BrowserAccessibilityFactory* factory);
 
+  // Called at the end of updating the tree.
+  virtual void OnUpdateFinished() {}
+
  private:
   // The following states keep track of whether or not the
   // on-screen keyboard is allowed to be shown.