cros: allow aura window not considered activatable for pointer event

ui/wm/core/focus_rules.h

Index: ui/wm/core/focus_rules.h
diff --git a/ui/wm/core/focus_rules.h b/ui/wm/core/focus_rules.h
index cb9a4ddbd8fa5d0d6a59227d19385a3c9031a9ae..a29ec941aa592ed13b540231e4b6cb0e8b8c22f0 100644
--- a/ui/wm/core/focus_rules.h
+++ b/ui/wm/core/focus_rules.h
@@ -11,6 +11,10 @@ namespace aura {
 class Window;
 }
 
+namespace ui {
+class Event;
+}
+
 namespace wm {
 
 // Implemented by an object that establishes the rules about what can be
@@ -26,9 +30,11 @@ class WM_EXPORT FocusRules {
   virtual bool IsToplevelWindow(aura::Window* window) const = 0;
   // Returns true if |window| can be activated or focused.
   virtual bool CanActivateWindow(aura::Window* window) const = 0;
-  // For CanFocusWindow(), NULL is supported, because NULL is a valid focusable
-  // window (in the case of clearing focus).
-  virtual bool CanFocusWindow(aura::Window* window) const = 0;
+  // For CanFocusWindow(), nullptr window is supported, because nullptr is a

[sky, 2017/04/17 16:08:48]

optional: in comments I think null is fine.

[Qiang(Joe) Xu, 2017/04/17 17:40:32]

Done.

+  // valid focusable window (in the case of clearing focus).
+  // |event| can be provided to check whether for the |event| the default focus

[sky, 2017/04/17 16:08:48]

How about:
If |event| is non-null it is the event triggering the focus change.

[Qiang(Joe) Xu, 2017/04/17 17:40:32]

Done.

+  // rules for |window| should be disabled.
+  virtual bool CanFocusWindow(aura::Window* window, ui::Event* event) const = 0;
 
   // Returns the toplevel window containing |window|. Not all toplevel windows
   // are activatable, call GetActivatableWindow() instead to return the