Attempt to re-land FocusManager removal from Aura.

ui/aura/client/focus_client.h

Index: ui/aura/client/focus_client.h
diff --git a/ui/aura/client/focus_client.h b/ui/aura/client/focus_client.h
index ff5f7f6b542caa6267b9c8a13c14e0a4a033b2d2..ad55d5ec6c0d3c84a0dd3a869017ca698e9c28b3 100644
--- a/ui/aura/client/focus_client.h
+++ b/ui/aura/client/focus_client.h
@@ -23,7 +23,6 @@ class AURA_EXPORT FocusClient {
  public:
   virtual ~FocusClient() {}
 
-  // TODO(beng): these methods will be OBSOLETE by FocusChangeEvent.
   virtual void AddObserver(FocusChangeObserver* observer) = 0;
   virtual void RemoveObserver(FocusChangeObserver* observer) = 0;
 
@@ -36,14 +35,6 @@ class AURA_EXPORT FocusClient {
 
   // Retrieves the focused window, or NULL if there is none.
   virtual Window* GetFocusedWindow() = 0;
-
-  // TODO(beng): temporary compat until FocusController is on.
-  // Called when |window|'s disposition in |root_window| changes such that
-  // focus must be shifted away from it. |destroyed| is true if the disposition
-  // change is that |window| is being destroyed.
-  virtual void OnWindowHiddenInRootWindow(aura::Window* window,
-                                          aura::RootWindow* root_window,
-                                          bool destroyed) = 0;
 };
 
 // Sets/Gets the focus client on the RootWindow.