Enable SitePerProcessAccessibilityBrowserTest on more platforms.

content/renderer/accessibility/blink_ax_tree_source.cc

Index: content/renderer/accessibility/blink_ax_tree_source.cc
diff --git a/content/renderer/accessibility/blink_ax_tree_source.cc b/content/renderer/accessibility/blink_ax_tree_source.cc
index 03207acec92e2112fe84b65d5edd83a80e94e40d..68809fafeda67333a5bfb1ec0eff70b8e68f5ad1 100644
--- a/content/renderer/accessibility/blink_ax_tree_source.cc
+++ b/content/renderer/accessibility/blink_ax_tree_source.cc
@@ -432,8 +432,7 @@ void BlinkAXTreeSource::SerializeNode(blink::WebAXObject src,
                            src.minValueForRange());
   }
 
-  if (dst->role == ui::AX_ROLE_DOCUMENT ||

[dmazzoni, 2015/01/28 19:29:01]

Fixing the other issues exposed this small bug. Our internal role of "WEB_AREA"
is what we use for the accessibility node for the HTML document object, it's the
root of an accessibility tree for one frame.

The role of DOCUMENT is totally different, it never should have been here. They
map to the same role on Windows, which is why this code was (incorrectly)
written that way. It was a harmless bug until now - with the other bugs in
FrameAccessibility fixed, this was triggering assertions because we were
treating it like it was the root of the accessibility tree for a frame, which
it's not.

-      dst->role == ui::AX_ROLE_WEB_AREA) {
+  if (dst->role == ui::AX_ROLE_WEB_AREA) {
     dst->AddStringAttribute(ui::AX_ATTR_HTML_TAG, "#document");
     const WebDocument& document = src.document();
     if (name.empty())