Implement sequential focus navigation for OOPIF.

content/renderer/render_frame_impl.cc

Index: content/renderer/render_frame_impl.cc
diff --git a/content/renderer/render_frame_impl.cc b/content/renderer/render_frame_impl.cc
index 0db8f24e912c0fabcddef7f30b37c8e696090b5a..eedcf80180dc0c91e7f2d518fa17efc2150dd2ba 100644
--- a/content/renderer/render_frame_impl.cc
+++ b/content/renderer/render_frame_impl.cc
@@ -1242,6 +1242,7 @@ bool RenderFrameImpl::OnMessageReceived(const IPC::Message& msg) {
     IPC_MESSAGE_HANDLER(FrameMsg_DidUpdateSandboxFlags, OnDidUpdateSandboxFlags)
     IPC_MESSAGE_HANDLER(FrameMsg_SetFrameOwnerProperties,
                         OnSetFrameOwnerProperties)
+    IPC_MESSAGE_HANDLER(FrameMsg_AdvanceFocus, OnAdvanceFocus)
     IPC_MESSAGE_HANDLER(FrameMsg_SetTextTrackSettings,
                         OnTextTrackSettingsChanged)
     IPC_MESSAGE_HANDLER(FrameMsg_PostMessageEvent, OnPostMessageEvent)
@@ -1800,6 +1801,15 @@ void RenderFrameImpl::OnSetFrameOwnerProperties(
   frame_->setFrameOwnerProperties(frame_owner_properties);
 }
 
+void RenderFrameImpl::OnAdvanceFocus(blink::WebFocusType type,
+                                     int source_routing_id) {
+  RenderFrameProxy* source_frame =
+      RenderFrameProxy::FromRoutingID(source_routing_id);
+
+  render_view_->webview()->advanceFocusAcrossFrames(
+      type, source_frame->web_frame(), frame_);

[Charlie Reis, 2015/12/04 21:44:50]

Should we null check source_frame?

[alexmos, 2015/12/04 22:21:18]

Done.  I suppose this is possible with race conditions (source frame being
deleted just as it's shifting focus to another frame).  I just abort the focus
shift for now: we won't be able to resume focus traversal from the right place
if the source frame is gone, so I think it's better to not try to focus
anything, rather than to focus an incorrect element.

[Charlie Reis, 2015/12/04 22:27:04]

Acknowledged.

+}
+
 void RenderFrameImpl::OnTextTrackSettingsChanged(
     const FrameMsg_TextTrackSettings_Params& params) {
   DCHECK(!frame_->parent());