Enable webkit_compositor_unittests

cc/CCLayerTreeHostImpl.cpp

 // Copyright 2011 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 "CCLayerTreeHostImpl.h"
 
 #include "CCActiveGestureAnimation.h"
 #include "CCAppendQuadsData.h"
@@ skipping 731 matching lines @@
 
     for (size_t i = 0; i < layerImpl->children().size(); ++i)
         adjustScrollsForPageScaleChange(layerImpl->children()[i].get(), pageScaleChange);
 }
 
 void CCLayerTreeHostImpl::setDeviceScaleFactor(float deviceScaleFactor)
 {
     if (deviceScaleFactor == m_deviceScaleFactor)
         return;
     m_deviceScaleFactor = deviceScaleFactor;
+
+    updateMaxScrollPosition();
 }
 
 
 void CCLayerTreeHostImpl::setPageScaleFactorAndLimits(float pageScale, float minPageScale, float maxPageScale)
 {
     if (!pageScale)
         return;
 
     if (m_sentPageScaleDelta == 1 && pageScale == m_pageScale && minPageScale == m_minPageScale && maxPageScale == m_maxPageScale)
         return;
@@ skipping 506 matching lines @@
 
     CCScrollbarAnimationController* scrollbarController = layer->scrollbarAnimationController();
     if (scrollbarController && scrollbarController->animate(monotonicTime))
         m_client->setNeedsRedrawOnImplThread();
 
     for (size_t i = 0; i < layer->children().size(); ++i)
         animateScrollbarsRecursive(layer->children()[i].get(), monotonicTime);
 }
 
 } // namespace WebCore