Introduce painted-device-scale-factor and use it when --enable-use-zoom-for-dsf is specified.

third_party/WebKit/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 394 matching lines @@
     , m_chromeClientImpl(ChromeClientImpl::create(this))
     , m_contextMenuClientImpl(this)
     , m_dragClientImpl(this)
     , m_editorClientImpl(this)
     , m_spellCheckerClientImpl(this)
     , m_storageClientImpl(this)
     , m_shouldAutoResize(false)
     , m_zoomLevel(0)
     , m_minimumZoomLevel(zoomFactorToZoomLevel(minTextSizeMultiplier))
     , m_maximumZoomLevel(zoomFactorToZoomLevel(maxTextSizeMultiplier))
+    , m_zoomFactorForDeviceScaleFactor(1.f)
+    , m_useZoomForDeviceScaleFactor(false)
     , m_maximumLegibleScale(1)
     , m_doubleTapZoomPageScaleFactor(0)
     , m_doubleTapZoomPending(false)
     , m_enableFakePageScaleAnimationForTesting(false)
     , m_fakePageScaleAnimationPageScaleFactor(0)
     , m_fakePageScaleAnimationUseAnchor(false)
     , m_doingDragAndDrop(false)
     , m_ignoreInputEvents(false)
     , m_compositorDeviceScaleFactorOverride(0)
     , m_rootLayerScale(1)
@@ skipping 2526 matching lines @@
     if (zoomLevel < m_minimumZoomLevel)
         m_zoomLevel = m_minimumZoomLevel;
     else if (zoomLevel > m_maximumZoomLevel)
         m_zoomLevel = m_maximumZoomLevel;
     else
         m_zoomLevel = zoomLevel;
 
     LocalFrame* frame = mainFrameImpl()->frame();
     if (!WebLocalFrameImpl::pluginContainerFromFrame(frame)) {
         float zoomFactor = m_zoomFactorOverride ? m_zoomFactorOverride : static_cast<float>(zoomLevelToZoomFactor(m_zoomLevel));
+        zoomFactor *= m_zoomFactorForDeviceScaleFactor;
         frame->setPageZoomFactor(zoomFactor);
     }
 
     return m_zoomLevel;
 }
 
 void WebViewImpl::zoomLimitsChanged(double minimumZoomLevel,
                                     double maximumZoomLevel)
 {
     m_minimumZoomLevel = minimumZoomLevel;
@@ skipping 116 matching lines @@
 float WebViewImpl::deviceScaleFactor() const
 {
     if (!page())
         return 1;
 
     return page()->deviceScaleFactor();
 }
 
 void WebViewImpl::setDeviceScaleFactor(float scaleFactor)
 {
-    if (!page())
-        return;
+    if (m_useZoomForDeviceScaleFactor) {
+        if (!m_layerTreeView || m_zoomFactorForDeviceScaleFactor == scaleFactor)
+            return;
+        m_zoomFactorForDeviceScaleFactor = scaleFactor;
+        setZoomLevel(m_zoomLevel);
+    } else {
+        if (!page())
+            return;
 
-    page()->setDeviceScaleFactor(scaleFactor);
+        page()->setDeviceScaleFactor(scaleFactor);
 
-    if (m_layerTreeView)
-        updateLayerTreeDeviceScaleFactor();
+        if (!m_layerTreeView)
+            return;
+    }
+    updateLayerTreeDeviceScaleFactor();
+}
+
+void WebViewImpl::enableUseZoomForDeviceScaleFactor()
+{
+    m_useZoomForDeviceScaleFactor = true;
 }
 
 void WebViewImpl::setDeviceColorProfile(const WebVector<char>& colorProfile)
 {
     if (!page())
         return;
 
     Vector<char> deviceProfile;
     deviceProfile.append(colorProfile.data(), colorProfile.size());
 
@@ skipping 1317 matching lines @@
     if (m_pageColorOverlay)
         m_pageColorOverlay->update();
     if (InspectorOverlay* overlay = inspectorOverlay()) {
         PageOverlay* inspectorPageOverlay = overlay->pageOverlay();
         if (inspectorPageOverlay)
             inspectorPageOverlay->update();
     }
 }
 
 } // namespace blink