Refactor viewport initialization logic out of WebViewImpl.

Source/core/page/Page.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All Rights Reserved.
  * Copyright (C) 2008 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * 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,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 413 matching lines @@
 
     m_defersLoading = defers;
     for (Frame* frame = mainFrame(); frame; frame = frame->tree()->traverseNext())
         frame->loader()->setDefersLoading(defers);
 }
 
 void Page::setPageScaleFactor(float scale, const IntPoint& origin)
 {
     FrameView* view = mainFrame()->view();
 
-    if (scale == m_pageScaleFactor) {
-        if (view && view->scrollPosition() != origin)
-            view->setScrollPosition(origin);
-        return;
+    bool oldProgrammaticScroll = view->inProgrammaticScroll();
+    view->setInProgrammaticScroll(false);
+
+    if (scale != m_pageScaleFactor) {
+        m_pageScaleFactor = scale;
+
+        if (view)
+            view->setVisibleContentScaleFactor(scale);
+
+        mainFrame()->deviceOrPageScaleFactorChanged();
+
+        if (view)
+            view->setViewportConstrainedObjectsNeedLayout();
     }
 
-    m_pageScaleFactor = scale;
+    if (view && view->scrollPosition() != origin)
+        view->notifyScrollPositionChanged(origin);
 
-    if (view)
-        view->setVisibleContentScaleFactor(scale);
-
-    mainFrame()->deviceOrPageScaleFactorChanged();
-
-    if (view)
-        view->setViewportConstrainedObjectsNeedLayout();
-
-    if (view && view->scrollPosition() != origin)
-        view->setScrollPosition(origin);
+    view->setInProgrammaticScroll(oldProgrammaticScroll);
 }
 
 void Page::setDeviceScaleFactor(float scaleFactor)
 {
     if (m_deviceScaleFactor == scaleFactor)
         return;
 
     m_deviceScaleFactor = scaleFactor;
     setNeedsRecalcStyleInAllFrames();
 
@@ skipping 365 matching lines @@
     , dragClient(0)
     , inspectorClient(0)
 {
 }
 
 Page::PageClients::~PageClients()
 {
 }
 
 } // namespace WebCore