Remove frameID hack for history.

Source/core/frame/Frame.cpp

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Simon Hausmann <hausmann@kde.org>
  *                     2000 Stefan Schimanski <1Stein@gmx.de>
  *                     2001 George Staikos <staikos@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2005 Alexey Proskuryakov <ap@nypop.com>
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
@@ skipping 36 matching lines @@
 #include "core/page/Page.h"
 #include "core/rendering/RenderPart.h"
 #include "public/platform/WebLayer.h"
 #include "wtf/PassOwnPtr.h"
 #include "wtf/RefCountedLeakCounter.h"
 
 namespace WebCore {
 
 using namespace HTMLNames;
 
-namespace {
-
-int64_t generateFrameID()
-{
-    // Initialize to the current time to reduce the likelihood of generating
-    // identifiers that overlap with those from past/future browser sessions.
-    static int64_t next = static_cast<int64_t>(currentTime() * 1000000.0);
-    return ++next;
-}
-
-} // namespace
-
 DEFINE_DEBUG_ONLY_GLOBAL(WTF::RefCountedLeakCounter, frameCounter, ("Frame"));
 
 Frame::Frame(FrameHost* host, HTMLFrameOwnerElement* ownerElement)
     : m_host(host)
     , m_ownerElement(ownerElement)
-    , m_frameID(generateFrameID())
     , m_remotePlatformLayer(0)
 {
     ASSERT(page());
 
 #ifndef NDEBUG
     frameCounter.increment();
 #endif
 
     if (this->ownerElement()) {
         page()->incrementSubframeCount();
@@ skipping 111 matching lines @@
 {
     if (ownerElement()) {
         ownerElement()->clearContentFrame();
         if (page())
             page()->decrementSubframeCount();
     }
     m_ownerElement = 0;
 }
 
 } // namespace WebCore