One accessibility tree per frame.

content/browser/accessibility/accessibility_tree_formatter_blink.cc

Index: content/browser/accessibility/accessibility_tree_formatter_blink.cc
diff --git a/content/browser/accessibility/accessibility_tree_formatter_blink.cc b/content/browser/accessibility/accessibility_tree_formatter_blink.cc
index 200c3375f45d6f7cf07d273543d3e1629106d329..b74fb1d91b6c2072ff36062ebd5acfb84a6c7540 100644
--- a/content/browser/accessibility/accessibility_tree_formatter_blink.cc
+++ b/content/browser/accessibility/accessibility_tree_formatter_blink.cc
@@ -39,7 +39,7 @@ void AccessibilityTreeFormatterBlink::AddProperties(
     base::DictionaryValue* dict) {
   dict->SetInteger("id", node.GetId());
 
-  dict->SetString("role", ui::ToString(node.GetData().role));
+  dict->SetString("internalRole", ui::ToString(node.GetData().role));
 
   dict->SetInteger("boundsX", node.GetData().location.x());
   dict->SetInteger("boundsY", node.GetData().location.y());
@@ -112,7 +112,7 @@ base::string16 AccessibilityTreeFormatterBlink::ToString(
   }
 
   base::string16 role_value;
-  dict.GetString("role", &role_value);
+  dict.GetString("internalRole", &role_value);

[David Tseng, 2016/03/04 16:50:20]

Why this change?

[dmazzoni, 2016/03/07 21:35:32]

It conflicted with the string attribute "role" (which stores the ARIA role as
specified by the user). This was the first case where those didn't happen to
result in printing the same string in a test.

   WriteAttribute(true, base::UTF16ToUTF8(role_value), &line);
 
   for (int state_index = ui::AX_STATE_NONE;