Re-land: Send Windows accessibility events based on tree updates.

content/browser/accessibility/browser_accessibility_manager_win.cc

Index: content/browser/accessibility/browser_accessibility_manager_win.cc
diff --git a/content/browser/accessibility/browser_accessibility_manager_win.cc b/content/browser/accessibility/browser_accessibility_manager_win.cc
index 200f832835b8130d79e44a106fe3e8cc541ccc8e..b760056efbc9bc7f9e64cb249ff96b604ae6fd35 100644
--- a/content/browser/accessibility/browser_accessibility_manager_win.cc
+++ b/content/browser/accessibility/browser_accessibility_manager_win.cc
@@ -73,8 +73,8 @@ IAccessible* BrowserAccessibilityManagerWin::GetParentIAccessible() {
   return delegate_->AccessibilityGetNativeViewAccessible();
 }
 
-void BrowserAccessibilityManagerWin::MaybeCallNotifyWinEvent(DWORD event,
-                                                             LONG child_id) {
+void BrowserAccessibilityManagerWin::MaybeCallNotifyWinEvent(
+    DWORD event, BrowserAccessibility* node) {
   if (!delegate_)
     return;
 
@@ -82,10 +82,46 @@ void BrowserAccessibilityManagerWin::MaybeCallNotifyWinEvent(DWORD event,
   if (!hwnd)
     return;
 
+  // Inline text boxes are an internal implementation detail, we don't
+  // expose them to Windows.
+  if (node->GetRole() == ui::AX_ROLE_INLINE_TEXT_BOX)
+    return;
+
+  // It doesn't make sense to fire a REORDER event on a leaf node; that
+  // happens when the node has internal children line inline text boxes.
+  if (event == EVENT_OBJECT_REORDER && node->PlatformIsLeaf())
+    return;
+
+  // Don't fire focus, or load complete notifications if the
+  // window isn't focused, because that can confuse screen readers into
+  // entering their "browse" mode.
+  if ((event == EVENT_OBJECT_FOCUS ||
+       event == IA2_EVENT_DOCUMENT_LOAD_COMPLETE) &&
+      (!delegate_->AccessibilityViewHasFocus())) {
+    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 == EVENT_OBJECT_FOCUS &&
+      node == GetRoot() &&
+      node->PlatformChildCount() == 0 &&
+      !node->HasState(ui::AX_STATE_BUSY) &&
+      !node->GetBoolAttribute(ui::AX_ATTR_DOC_LOADED)) {
+    return;
+  }
+
+  // If a focus event is needed on the root, fire that first before
+  // this event.
+  if (event == EVENT_OBJECT_FOCUS && node == GetRoot())
+    focus_event_on_root_needed_ = false;
+  else if (focus_event_on_root_needed_)
+    OnWindowFocused();
+
+  LONG child_id = node->ToBrowserAccessibilityWin()->unique_id_win();

[aboxhall, 2015/01/22 21:22:09]

Why is (was) this called child_id rather than node_id?

[dmazzoni, 2015/01/23 23:26:13]

That's the name of the ::NotifyWinEvent parameter, on the next line. For legacy
reasons, you can't call NotifyWinEvent on a MSAA object, you have to call it on
an HWND, with a child id - then the client asks the HWND for the child with that
id and we can treat that child id as a global id rather than a 1-based index.

If you want the gory details:
https://developer.mozilla.org/en-US/docs/Web/Accessibility/Implementing_MSAA_...

   ::NotifyWinEvent(event, hwnd, OBJID_CLIENT, child_id);
 }
 
-
 void BrowserAccessibilityManagerWin::OnNodeCreated(ui::AXNode* node) {
   BrowserAccessibilityManager::OnNodeCreated(node);
   BrowserAccessibility* obj = GetFromAXNode(node);
@@ -129,41 +165,6 @@ void BrowserAccessibilityManagerWin::OnWindowFocused() {
 void BrowserAccessibilityManagerWin::NotifyAccessibilityEvent(
     ui::AXEvent event_type,
     BrowserAccessibility* node) {
-  if (!delegate_ || !delegate_->AccessibilityGetAcceleratedWidget())
-    return;
-
-  // Inline text boxes are an internal implementation detail, we don't
-  // expose them to Windows.
-  if (node->GetRole() == ui::AX_ROLE_INLINE_TEXT_BOX)
-    return;
-
-  // Don't fire focus, blur, or load complete notifications if the
-  // window isn't focused, because that can confuse screen readers into
-  // entering their "browse" mode.
-  if ((event_type == ui::AX_EVENT_FOCUS ||
-       event_type == ui::AX_EVENT_BLUR ||
-       event_type == ui::AX_EVENT_LOAD_COMPLETE) &&
-      (!delegate_ || !delegate_->AccessibilityViewHasFocus())) {
-    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->HasState(ui::AX_STATE_BUSY) &&
-      !node->GetBoolAttribute(ui::AX_ATTR_DOC_LOADED)) {
-    return;
-  }
-
-  // If a focus event is needed on the root, fire that first before
-  // this event.
-  if (event_type == ui::AX_EVENT_FOCUS && node == GetRoot())
-    focus_event_on_root_needed_ = false;
-  else if (focus_event_on_root_needed_)
-    OnWindowFocused();
-
   LONG event_id = EVENT_MIN;
   switch (event_type) {
     case ui::AX_EVENT_ACTIVEDESCENDANTCHANGED:
@@ -172,9 +173,6 @@ void BrowserAccessibilityManagerWin::NotifyAccessibilityEvent(
     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;
-      break;
     case ui::AX_EVENT_AUTOCORRECTION_OCCURED:
       event_id = IA2_EVENT_OBJECT_ATTRIBUTE_CHANGED;
       break;
@@ -183,18 +181,12 @@ void BrowserAccessibilityManagerWin::NotifyAccessibilityEvent(
       event_id = EVENT_OBJECT_FOCUS;
       node = GetRoot();
       break;
-    case ui::AX_EVENT_CHECKED_STATE_CHANGED:
-      event_id = EVENT_OBJECT_STATECHANGE;
-      break;
     case ui::AX_EVENT_CHILDREN_CHANGED:
       event_id = EVENT_OBJECT_REORDER;
       break;
     case ui::AX_EVENT_FOCUS:
       event_id = EVENT_OBJECT_FOCUS;
       break;
-    case ui::AX_EVENT_INVALID_STATUS_CHANGED:
-      event_id = EVENT_OBJECT_STATECHANGE;
-      break;
     case ui::AX_EVENT_LIVE_REGION_CHANGED:
       if (node->GetBoolAttribute(ui::AX_ATTR_CONTAINER_LIVE_BUSY))
         return;
@@ -209,12 +201,6 @@ void BrowserAccessibilityManagerWin::NotifyAccessibilityEvent(
     case ui::AX_EVENT_MENU_LIST_VALUE_CHANGED:
       event_id = EVENT_OBJECT_VALUECHANGE;
       break;
-    case ui::AX_EVENT_HIDE:
-      event_id = EVENT_OBJECT_HIDE;
-      break;
-    case ui::AX_EVENT_SHOW:
-      event_id = EVENT_OBJECT_SHOW;
-      break;
     case ui::AX_EVENT_SCROLL_POSITION_CHANGED:
       event_id = EVENT_SYSTEM_SCROLLINGEND;
       break;
@@ -224,15 +210,9 @@ void BrowserAccessibilityManagerWin::NotifyAccessibilityEvent(
     case ui::AX_EVENT_SELECTED_CHILDREN_CHANGED:
       event_id = EVENT_OBJECT_SELECTIONWITHIN;
       break;
-    case ui::AX_EVENT_TEXT_CHANGED:
-      event_id = EVENT_OBJECT_NAMECHANGE;
-      break;
     case ui::AX_EVENT_TEXT_SELECTION_CHANGED:
       event_id = IA2_EVENT_TEXT_CARET_MOVED;
       break;
-    case ui::AX_EVENT_VALUE_CHANGED:
-      event_id = EVENT_OBJECT_VALUECHANGE;
-      break;
     default:
       // Not all WebKit accessibility events result in a Windows
       // accessibility notification.
@@ -244,8 +224,7 @@ void BrowserAccessibilityManagerWin::NotifyAccessibilityEvent(
     // 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();
-    MaybeCallNotifyWinEvent(event_id, child_id);
+    MaybeCallNotifyWinEvent(event_id, node);
   }
 
   // If this is a layout complete notification (sent when a container scrolls)
@@ -255,8 +234,7 @@ void BrowserAccessibilityManagerWin::NotifyAccessibilityEvent(
       tracked_scroll_object_ &&
       tracked_scroll_object_->IsDescendantOf(node)) {
     MaybeCallNotifyWinEvent(
-        IA2_EVENT_VISIBLE_DATA_CHANGED,
-        tracked_scroll_object_->ToBrowserAccessibilityWin()->unique_id_win());
+        IA2_EVENT_VISIBLE_DATA_CHANGED, tracked_scroll_object_);
     tracked_scroll_object_->Release();
     tracked_scroll_object_ = NULL;
   }
@@ -265,11 +243,20 @@ void BrowserAccessibilityManagerWin::NotifyAccessibilityEvent(
 void BrowserAccessibilityManagerWin::OnAtomicUpdateFinished(
     bool root_changed,
     const std::vector<ui::AXTreeDelegate::Change>& changes) {
+  BrowserAccessibilityManager::OnAtomicUpdateFinished(root_changed, changes);
+
   if (root_changed) {
     // In order to make screen readers aware of the new accessibility root,
     // we need to fire a focus event on it.
     OnWindowFocused();
   }
+
+  // Second pass.

[aboxhall, 2015/01/22 21:22:09]

Why do we need to do a second pass?

[dmazzoni, 2015/01/23 23:26:13]

Because updating IAccessibleText requires the children are updated first.

I updated the comment to explain why.

+  for (size_t i = 0; i < changes.size(); ++i) {
+    BrowserAccessibility* obj = GetFromAXNode(changes[i].node);
+    if (obj)
+      obj->ToBrowserAccessibilityWin()->UpdateIAccessibleText();
+  }
 }
 
 void BrowserAccessibilityManagerWin::TrackScrollingObject(