Refactor WindowFinder definition

chrome/browser/ui/views/tabs/window_finder_mac.mm

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/views/tabs/window_finder.h"
 
 #import <AppKit/AppKit.h>
 
 #include "ui/gfx/geometry/point.h"
 #import "ui/gfx/mac/coordinate_conversion.h"
 
 gfx::NativeWindow WindowFinder::GetLocalProcessWindowAtPoint(
     const gfx::Point& screen_point,
     const std::set<gfx::NativeWindow>& ignore) {
+  return GetLocalProcessWindowAtPointImpl(screen_point, ignore);
+}
+
+gfx::NativeWindow WindowFinder::GetLocalProcessWindowAtPointImpl(
+    const gfx::Point& screen_point,
+    const std::set<gfx::NativeWindow>& ignore) {
   const NSPoint ns_point = gfx::ScreenPointToNSPoint(screen_point);
 
   // Note: [NSApp orderedWindows] doesn't include NSPanels.
   for (NSWindow* window : [NSApp orderedWindows]) {
     if (ignore.count(window))
       continue;
 
     if (![window isOnActiveSpace])
       continue;
 
     // NativeWidgetMac::Close() calls -orderOut: on NSWindows before actually
     // closing them.
     if (![window isVisible])
       continue;
 
     if (NSPointInRect(ns_point, [window frame]))
       return window;
   }
 
   return nil;
 }