Merge to 53: On the Mac, AX_EVENT_LOAD_COMPLETE should only be fired on the top document.

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 45957d9acbd21c31f46c6c66c9cbce0563e31af8..660f556e282b052cbf38395c4f2bc63dd881d41a 100644
--- a/content/browser/accessibility/browser_accessibility_manager.h
+++ b/content/browser/accessibility/browser_accessibility_manager.h
@@ -366,6 +366,9 @@ class CONTENT_EXPORT BrowserAccessibilityManager : public ui::AXTreeDelegate {
   // Returns the BrowserAccessibilityDelegate from |GetRootManager|, above.
   BrowserAccessibilityDelegate* GetDelegateFromRootManager();
 
+  // Returns whether this is the top document.
+  bool IsRootTree();
+
   // Get a snapshot of the current tree as an AXTreeUpdate.
   ui::AXTreeUpdate SnapshotAXTreeForTesting();