Implement 'sequential focus navigation starting point.'

third_party/WebKit/Source/core/page/FocusController.cpp

 /*
  * Copyright (C) 2006, 2007 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nuanti Ltd.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 725 matching lines @@
 }
 
 bool FocusController::advanceFocusInDocumentOrder(LocalFrame* frame, Element* start, WebFocusType type, bool initialFocus, InputDeviceCapabilities* sourceCapabilities)
 {
     ASSERT(frame);
     Document* document = frame->document();
     ASSERT(document->documentElement());
 
     Element* current = start;
     if (!current)
-        current = document->focusedElement();
+        current = document->sequentialFocusNavigationStartingPoint(type);
 
     // FIXME: Not quite correct when it comes to focus transitions leaving/entering the WebView itself
     bool caretBrowsing = frame->settings() && frame->settings()->caretBrowsingEnabled();
 
     if (caretBrowsing && !current)
         current = adjustToElement(frame->selection().start().anchorNode(), type);
 
     document->updateLayoutIgnorePendingStylesheets();
 
     RefPtrWillBeRawPtr<Element> element = findFocusableElementAcrossFocusScopes(type, FocusNavigationScope::focusNavigationScopeOf(current ? *current : *document->documentElement()), current);
 
     if (!element) {
         // If there's a RemoteFrame on the ancestor chain, we need to continue
         // searching for focusable elements there.
         if (frame->localFrameRoot() != frame->tree().top()) {
             document->clearFocusedElement();
+            document->setSequentialFocusNavigationStartingPoint(nullptr);
             toRemoteFrame(frame->localFrameRoot()->tree().parent())->advanceFocus(type, frame->localFrameRoot());
             return true;
         }
 
         // We didn't find an element to focus, so we should try to pass focus to Chrome.
         if (!initialFocus && m_page->chromeClient().canTakeFocus(type)) {
             document->clearFocusedElement();
+            document->setSequentialFocusNavigationStartingPoint(nullptr);
             setFocusedFrame(nullptr);
             m_page->chromeClient().takeFocus(type);
             return true;
         }
 
         // Chrome doesn't want focus, so we should wrap focus.
         element = findFocusableElementRecursively(type, FocusNavigationScope::focusNavigationScopeOf(*toLocalFrame(m_page->mainFrame())->document()->documentElement()), nullptr);
         element = findFocusableElementDescendingDownIntoFrameDocument(type, element.get());
 
         if (!element)
@@ skipping 355 matching lines @@
     return consumed;
 }
 
 DEFINE_TRACE(FocusController)
 {
     visitor->trace(m_page);
     visitor->trace(m_focusedFrame);
 }
 
 } // namespace blink