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 f20b6517ac0d88e3cef9a9d0c3a032a0b8e85c8e..d9451b93a78f143b589ba3de6dbe4e7085abf7cb 100644
--- a/content/browser/accessibility/browser_accessibility_manager.h
+++ b/content/browser/accessibility/browser_accessibility_manager.h
@@ -192,6 +192,9 @@ class CONTENT_EXPORT BrowserAccessibilityManager : public ui::AXTreeDelegate {
       BrowserAccessibilityDelegate* delegate,
       BrowserAccessibilityFactory* factory);
 
+  // Called at the end of updating the tree.
+  virtual void OnTreeUpdateFinished() {}
+
  private:
   // The following states keep track of whether or not the
   // on-screen keyboard is allowed to be shown.