Port more focus controller unit tests and fix our focus rules.

services/window_manager/focus_rules.h

Index: services/window_manager/focus_rules.h
diff --git a/services/window_manager/focus_rules.h b/services/window_manager/focus_rules.h
index 3d97f0c1e0341a971f34feb91f34ed7556732553..83fd1d59bdb58f13b2ad5104da2fb17fe20c910d 100644
--- a/services/window_manager/focus_rules.h
+++ b/services/window_manager/focus_rules.h
@@ -16,6 +16,9 @@ class FocusRules {
  public:
   virtual ~FocusRules() {}
 
+  // Returns true if the children of |window| can be activated.
+  virtual bool SupportsChildActivation(View* window) const = 0;
+
   // Returns true if |view| is a toplevel view. Whether or not a view
   // is considered toplevel is determined by a similar set of rules that
   // govern activation and focus. Not all toplevel views are activatable,