Fix keyboard focus for OOPIF-<webview>.

content/browser/frame_host/frame_tree.cc

Index: content/browser/frame_host/frame_tree.cc
diff --git a/content/browser/frame_host/frame_tree.cc b/content/browser/frame_host/frame_tree.cc
index 9977976aaba40eb87ec1c970367ba9b3f85a4053..cf9f2e647bfde775d9ecfc23e46497105e172a24 100644
--- a/content/browser/frame_host/frame_tree.cc
+++ b/content/browser/frame_host/frame_tree.cc
@@ -251,6 +251,17 @@ void FrameTree::SetFocusedFrame(FrameTreeNode* node, SiteInstance* source) {
   if (node == GetFocusedFrame())
     return;
 
+  if (node == nullptr) {

[alexmos, 2016/05/19 00:08:09]

Can you add a comment above this, explaining that we might call this with a null
node when clearing focus for an inner WebContents?

[alexmos, 2016/05/19 00:08:09]

nit: !node

[avallee, 2016/05/24 20:07:07]

Done.

+    if (GetFocusedFrame())
+      GetFocusedFrame()->current_frame_host()->ClearFocusedFrame();
+    focused_frame_tree_node_id_ = FrameTreeNode::kFrameTreeNodeInvalidId;
+
+    // TODO(avallee): https://crbug.com/610795 This line is not sufficient to
+    // make the test pass. There seems to be no focus change events generated.
+    root()->current_frame_host()->UpdateAXTreeData();

[alexmos, 2016/05/19 00:08:09]

Should all three statements in the outer if only happen if (!node &&
GetFocusedFrame())?  Seems like you'd call UpdateAXTreeData redundantly if you
try to clear focus from a FrameTree that already had it cleared.

[avallee, 2016/05/24 20:07:07]

If already nullptr, then:
 if (node == GetFocusedFrame()) 
above would early-out.

+    return;
+  }
+
   std::set<SiteInstance*> frame_tree_site_instances =
       CollectSiteInstances(this);