Avoid mutating frame unique name after first real commit.

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

 /*
  * Copyright (C) Research In Motion Limited 2010. All rights reserved.
  * Copyright (C) 2006 Apple Computer, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 55 matching lines @@
 
     // Do not recalculate m_uniqueName if there is no real change of m_name.
     // This is not just a performance optimization - other code relies on the
     // assumption that unique name shouldn't change if the assigned name didn't
     // change (i.e. code in content::FrameTreeNode::SetFrameName).
     if (m_name == name)
         return;
 
     m_name = name;
 
+    // https://crbug.com/607205: Make sure m_uniqueName doesn't change after
+    // initial navigation - session history depends on this.
+    if (m_thisFrame->isLocalFrame()) {

[dcheng, 2016/09/07 19:54:13]

This check is redundant (see the DCHECK on line 59 =)

[Łukasz Anforowicz, 2016/09/09 16:21:38]

Done.

+        LocalFrame* localFrame = toLocalFrame(m_thisFrame);
+        if (localFrame->loader().stateMachine()->committedFirstRealDocumentLoad())
+            return;
+    }
+
     // Remove our old frame name so it's not considered in calculateUniqueNameForChildFrame
     // and appendUniqueSuffix calls below.
     m_uniqueName = AtomicString();
 
     // Calculate a new unique name based on inputs.
     if (parent()) {
         setUniqueName(
             parent()->tree().calculateUniqueNameForChildFrame(m_thisFrame, name, nullAtom));
     } else if (name.isEmpty() || !uniqueNameExists(name)) {
         // Only main frame can have an empty unique name, so for main frames
@@ skipping 508 matching lines @@
 {
     if (!frame) {
         printf("Null input frame\n");
         return;
     }
 
     printFrames(frame->tree().top(), frame, 0);
 }
 
 #endif