Add hack so VoiceOver speaks updates to injected live regions.

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 fba13beadabc3c5180c7ef2cce061a26f3f024d0..53d776bc287536c0c13f608cb3846c9b6f07ae56 100644
--- a/content/browser/accessibility/browser_accessibility_manager_mac.mm
+++ b/content/browser/accessibility/browser_accessibility_manager_mac.mm
@@ -6,6 +6,7 @@
 
 #import "base/logging.h"
 #import "content/browser/accessibility/browser_accessibility_cocoa.h"
+#import "content/browser/accessibility/browser_accessibility_mac.h"
 #include "content/common/accessibility_messages.h"
 
 namespace content {
@@ -25,7 +26,8 @@ BrowserAccessibilityManagerMac::BrowserAccessibilityManagerMac(
     BrowserAccessibilityDelegate* delegate,
     BrowserAccessibilityFactory* factory)
     : BrowserAccessibilityManager(initial_tree, delegate, factory),
-      parent_view_(parent_view) {
+      parent_view_(parent_view),
+      created_live_region_(false) {
 }
 
 // static
@@ -154,4 +156,27 @@ void BrowserAccessibilityManagerMac::NotifyAccessibilityEvent(
   NSAccessibilityPostNotification(native_node, event_id);
 }
 
+void BrowserAccessibilityManagerMac::OnNodeCreationFinished(ui::AXNode* node) {
+  BrowserAccessibility* obj = GetFromAXNode(node);
+  if (obj && obj->HasStringAttribute(ui::AX_ATTR_LIVE_STATUS))
+    created_live_region_ = true;
+}
+
+void BrowserAccessibilityManagerMac::OnTreeUpdateFinished() {
+  if (!created_live_region_)
+    return;
+
+  // This code is to work around a bug in VoiceOver, where a new live
+  // region that gets added is ignored. VoiceOver seems to only scan the
+  // page for live regions once. By recreating the NSAccessibility
+  // object for the root of the tree, we force VoiceOver to clear out its
+  // internal state and find newly-added live regions this time.
+  BrowserAccessibilityMac* root =
+      static_cast<BrowserAccessibilityMac*>(GetRoot());
+  root->RecreateNativeObject();
+  NotifyAccessibilityEvent(ui::AX_EVENT_CHILDREN_CHANGED, root);
+
+  created_live_region_ = false;
+}
+
 }  // namespace content