Implement WebFrame::swap.

Source/web/OpenedFrameTracker.cpp

 // 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 "config.h"
 #include "web/OpenedFrameTracker.h"
 
 #include "public/web/WebFrame.h"
 
 namespace blink {
 
 OpenedFrameTracker::OpenedFrameTracker()
 {
 }
 
 OpenedFrameTracker::~OpenedFrameTracker()
 {
-    HashSet<WebFrame*>::iterator end = m_openedFrames.end();
-    for (HashSet<WebFrame*>::iterator it = m_openedFrames.begin(); it != end; ++it)
-        (*it)->m_opener = 0;
+    updateOpener(0);
+}
+
+bool OpenedFrameTracker::isEmpty() const
+{
+    return m_openedFrames.isEmpty();
 }
 
 void OpenedFrameTracker::add(WebFrame* frame)
 {
     m_openedFrames.add(frame);
 }
 
 void OpenedFrameTracker::remove(WebFrame* frame)
 {
     m_openedFrames.remove(frame);
 }
 
+void OpenedFrameTracker::updateOpener(WebFrame* frame)
+{
+    HashSet<WebFrame*>::iterator end = m_openedFrames.end();
+    for (HashSet<WebFrame*>::iterator it = m_openedFrames.begin(); it != end; ++it)
+        (*it)->m_opener = frame;
+}
+
 } // namespace blink