Fire load complete notifications on Mac even when page loads quickly.

content/browser/accessibility/browser_accessibility_manager_mac.mm

Index: content/browser/accessibility/browser_accessibility_manager_mac.mm
diff --git a/content/browser/accessibility/browser_accessibility_manager_mac.mm b/content/browser/accessibility/browser_accessibility_manager_mac.mm
index c71ffbe2b2120b9688d9efffa53e215141b5696c..1a976e35d250eed54ebd99f358d0ae657606ca36 100644
--- a/content/browser/accessibility/browser_accessibility_manager_mac.mm
+++ b/content/browser/accessibility/browser_accessibility_manager_mac.mm
@@ -577,6 +577,9 @@ void BrowserAccessibilityManagerMac::OnAtomicUpdateFinished(
         tree_events_[live_root->id()].insert(ui::AX_EVENT_LIVE_REGION_CHANGED);
     }
   }
+
+  if (root_changed && tree->data().loaded)
+    tree_events_[tree->root()->id()].insert(ui::AX_EVENT_LOAD_COMPLETE);
 }
 
 NSDictionary* BrowserAccessibilityManagerMac::