Fix bug where NVDA wouldn't enter browse mode on page load.

content/browser/accessibility/browser_accessibility_manager_win.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/accessibility/browser_accessibility_manager_win.h"
 
 #include "base/command_line.h"
 #include "base/win/scoped_comptr.h"
 #include "base/win/windows_version.h"
 #include "content/browser/accessibility/browser_accessibility_state_impl.h"
@@ skipping 116 matching lines @@
   if (focus_ != tree_->GetRoot())
     NotifyAccessibilityEvent(ui::AX_EVENT_BLUR, GetRoot());
 }
 
 void BrowserAccessibilityManagerWin::NotifyAccessibilityEvent(
     ui::AXEvent event_type,
     BrowserAccessibility* node) {
   if (node->GetRole() == ui::AX_ROLE_INLINE_TEXT_BOX)
     return;
 
+  // NVDA gets confused if we focus the main document element when it hasn't
+  // finished loading and it has no children at all, so suppress that event.
+  if (event_type == ui::AX_EVENT_FOCUS &&
+      node == GetRoot() &&
+      node->PlatformChildCount() == 0 &&
+      !node->GetBoolAttribute(ui::AX_ATTR_DOC_LOADED)) {
+    return;
+  }
+
   LONG event_id = EVENT_MIN;
   switch (event_type) {
     case ui::AX_EVENT_ACTIVEDESCENDANTCHANGED:
       event_id = IA2_EVENT_ACTIVE_DESCENDANT_CHANGED;
       break;
     case ui::AX_EVENT_ALERT:
       event_id = EVENT_SYSTEM_ALERT;
       break;
     case ui::AX_EVENT_ARIA_ATTRIBUTE_CHANGED:
       event_id = IA2_EVENT_OBJECT_ATTRIBUTE_CHANGED;
@@ skipping 67 matching lines @@
       // accessibility notification.
       break;
   }
 
   if (event_id != EVENT_MIN) {
     // Pass the node's unique id in the |child_id| argument to NotifyWinEvent;
     // the AT client will then call get_accChild on the HWND's accessibility
     // object and pass it that same id, which we can use to retrieve the
     // IAccessible for this node.
     LONG child_id = node->ToBrowserAccessibilityWin()->unique_id_win();
+
+    // Always send a focus before a load complete.
+    if (event_type == ui::AX_EVENT_LOAD_COMPLETE)
+      MaybeCallNotifyWinEvent(EVENT_OBJECT_FOCUS, child_id);

[aboxhall, 2014/06/12 22:31:45]

Why is this necessary to fix this issue? Superficially it seems like this would
be the opposite of what you wanted, so I'm just curious.

[dmazzoni, 2014/06/12 23:27:22]

When we get a load complete, we know the document is fully loaded - it's
required to send a focus before sending a load complete. The fix up above says
to not send a focus if the document has only begun loading.

     MaybeCallNotifyWinEvent(event_id, child_id);
   }
 
   // If this is a layout complete notification (sent when a container scrolls)
   // and there is a descendant tracked object, send a notification on it.
   // TODO(dmazzoni): remove once http://crbug.com/113483 is fixed.
   if (event_type == ui::AX_EVENT_LAYOUT_COMPLETE &&
       tracked_scroll_object_ &&
       tracked_scroll_object_->IsDescendantOf(node)) {
     MaybeCallNotifyWinEvent(
@@ skipping 34 matching lines @@
   // |parent_iaccessible_| are no longer valid either, since they were
   // derived from AccessibleHWND. We don't have to restore them to
   // previous values, though, because this should only happen
   // during the destruct sequence for this window.
   accessible_hwnd_ = NULL;
   parent_hwnd_ = NULL;
   parent_iaccessible_ = NULL;
 }
 
 }  // namespace content