Enable WebViewAccessiblityTest for OOPIF webview.

content/browser/frame_host/render_frame_host_impl.cc

Index: content/browser/frame_host/render_frame_host_impl.cc
diff --git a/content/browser/frame_host/render_frame_host_impl.cc b/content/browser/frame_host/render_frame_host_impl.cc
index 0f36645dfa22baa231d1f6c6bb9fbf0edc5d186e..62db75c98180f91ac7476bf4de71148849819cc6 100644
--- a/content/browser/frame_host/render_frame_host_impl.cc
+++ b/content/browser/frame_host/render_frame_host_impl.cc
@@ -3330,8 +3330,9 @@ void RenderFrameHostImpl::AXContentTreeDataToAXTreeData(
   FrameTreeNode* focused_frame_tree_node = frame_tree_->GetFocusedFrame();
   if (!focused_frame_tree_node)
     return;
-  RenderFrameHostImpl* focused_frame =
-      focused_frame_tree_node->current_frame_host();
+
+  auto* focused_frame = static_cast<RenderFrameHostImpl*>(
+      delegate_->GetFrameAtNode(focused_frame_tree_node));

[dmazzoni, 2017/02/16 00:19:02]

Maybe it'd be cleaner if you called it GetFocusedFrameIncludingGuestWebContents
or something like that
and had it take no arguments rather than taking in a FrameTreeNode
that's only halfway helpful.

[avallee, 2017/02/21 20:00:31]

Reworked to just navigate down the WebContents tree and finding one
RenderFrameHost (or null if no focus in the top WebContents).

   DCHECK(focused_frame);
   dst->focused_tree_id = focused_frame->GetAXTreeID();
 }