Implement initial support for nesting one ax tree in another.

content/browser/accessibility/browser_accessibility.cc

Index: content/browser/accessibility/browser_accessibility.cc
diff --git a/content/browser/accessibility/browser_accessibility.cc b/content/browser/accessibility/browser_accessibility.cc
index fe71fef965aa95dfdd32a16d0c22d738e9430e99..a6a5591e206dcf48662abec1f1127fd710e0a462 100644
--- a/content/browser/accessibility/browser_accessibility.cc
+++ b/content/browser/accessibility/browser_accessibility.cc
@@ -9,6 +9,7 @@
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "content/browser/accessibility/browser_accessibility_manager.h"
+#include "content/browser/accessibility/frame_tree_accessibility.h"
 #include "content/common/accessibility_messages.h"
 
 namespace content {
@@ -26,7 +27,8 @@ BrowserAccessibility* BrowserAccessibility::Create() {
 
 BrowserAccessibility::BrowserAccessibility()
     : manager_(NULL),
-      node_(NULL) {
+      node_(NULL),
+      child_frame_id_(0) {

[David Tseng, 2014/05/01 18:07:54]

Maybe the id should be a uint32?

[dmazzoni, 2014/05/05 07:17:57]

Done.

 }
 
 BrowserAccessibility::~BrowserAccessibility() {
@@ -63,7 +65,12 @@ bool BrowserAccessibility::PlatformIsLeaf() const {
 }
 
 uint32 BrowserAccessibility::PlatformChildCount() const {
-  return PlatformIsLeaf() ? 0 : InternalChildCount();
+  if (!child_frame_id_)

[David Tseng, 2014/05/01 18:07:54]

So, 0 means no iframe? Would it make sense to define that as a named constant?

[dmazzoni, 2014/05/05 07:17:57]

Done.

+    return PlatformIsLeaf() ? 0 : InternalChildCount();
+  FrameTreeAccessibility* frames = FrameTreeAccessibility::GetInstance();
+  BrowserAccessibilityManager* child_manager =
+      frames->FindAccessibilityManagerById(child_frame_id_);
+  return child_manager ? 1 : 0;
 }
 
 bool BrowserAccessibility::IsNative() const {
@@ -83,6 +90,13 @@ bool BrowserAccessibility::IsDescendantOf(
 
 BrowserAccessibility* BrowserAccessibility::PlatformGetChild(
     uint32 child_index) const {
+  if (child_index == 0 && child_frame_id_ != 0) {

[David Tseng, 2014/05/01 18:07:54]

A named constant would help the readability of this statement.

[David Tseng, 2014/05/01 18:07:54]

Crazy question...but can an iframe element have children besides another
document? (e.g. scroll bars, groups, etc).

[dmazzoni, 2014/05/05 07:17:57]

Done.

[dmazzoni, 2014/05/05 07:17:57]

No - but even if that were the case that shouldn't really matter, in Blink we
could just add a mock node in the middle. On the browser side we really don't
need to care about what these nodes are, we just replace any children with a
link to the root node of another tree.

Anything that says iframe here should be illustrative - the implementation here
should be more general than that and should apply to any way to embed one tree
in another, like <webview>.

+    FrameTreeAccessibility* frames = FrameTreeAccessibility::GetInstance();
+    BrowserAccessibilityManager* child_manager =
+        frames->FindAccessibilityManagerById(child_frame_id_);
+    return child_manager ? child_manager->GetRoot() : NULL;
+  }
+
   DCHECK(child_index < InternalChildCount());
   return InternalGetChild(child_index);
 }
@@ -122,7 +136,9 @@ BrowserAccessibility* BrowserAccessibility::GetParent() const {
   if (!node_ || !manager_)
     return NULL;
   ui::AXNode* parent = node_->parent();
-  return parent ? manager_->GetFromAXNode(parent) : NULL;
+  if (parent)
+    return manager_->GetFromAXNode(parent);
+  return manager_->GetCrossFrameParent();
 }
 
 int32 BrowserAccessibility::GetIndexInParent() const {
@@ -680,4 +696,9 @@ int BrowserAccessibility::GetStaticTextLenRecursive() const {
   return len;
 }
 
+void BrowserAccessibility::SetChildFrameId(int child_frame_id) {
+  child_frame_id_ = child_frame_id;
+  manager_->NotifyAccessibilityEvent(ui::AX_EVENT_CHILDREN_CHANGED, this);
+}
+
 }  // namespace content