Update viewport trigger for GPU rasterization

Source/web/WebViewImpl.cpp

 /*
  * Copyright (C) 2011, 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 2896 matching lines @@
         view->layout();
 }
 
 void WebViewImpl::updatePageDefinedViewportConstraints(const ViewportDescription& description)
 {
     if (!settings()->viewportEnabled() || !page() || (!m_size.width && !m_size.height))
         return;
 
     Document* document = page()->mainFrame()->document();
 
-    m_matchesHeuristicsForGpuRasterization = description.minimalUI
+    m_matchesHeuristicsForGpuRasterization = description.maxWidth == Length(DeviceWidth)
         && description.minZoom == 1.0
-        && description.minWidth == Length(ExtendToZoom)
-        && description.maxWidth == Length(DeviceWidth);
+        && description.minZoomIsExplicit
+        && description.zoom == 1.0
+        && description.zoomIsExplicit
+        && description.userZoom
+        && description.userZoomIsExplicit;
     if (m_layerTreeView)
         m_layerTreeView->heuristicsForGpuRasterizationUpdated(m_matchesHeuristicsForGpuRasterization);
 
     Length defaultMinWidth = document->viewportDefaultMinWidth();
     if (defaultMinWidth.isAuto())
         defaultMinWidth = Length(ExtendToZoom);
 
     ViewportDescription adjustedDescription = description;
     if (settingsImpl()->viewportMetaLayoutSizeQuirk() && adjustedDescription.type == ViewportDescription::ViewportMeta) {
         const int legacyWidthSnappingMagicNumber = 320;
@@ skipping 1152 matching lines @@
     const PageScaleConstraints& constraints = m_pageScaleConstraintsSet.pageDefinedConstraints();
 
     if (!mainFrameImpl() || !mainFrameImpl()->frameView())
         return false;
 
     return mainFrameImpl()->frameView()->layoutSize().width() == m_size.width
         || (constraints.minimumScale == constraints.maximumScale && constraints.minimumScale != -1);
 }
 
 } // namespace blink