Remove the forceCompositingMode setting.

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 1708 matching lines @@
 void WebViewImpl::layout()
 {
     TRACE_EVENT0("webkit", "WebViewImpl::layout");
     PageWidgetDelegate::layout(m_page.get());
     updateLayerTreeBackgroundColor();
 
     for (size_t i = 0; i < m_linkHighlights.size(); ++i)
         m_linkHighlights[i]->updateGeometry();
 }
 
-void WebViewImpl::enterForceCompositingMode(bool enter)
-{
-    if (page()->settings().forceCompositingMode() == enter)
-        return;
-
-    TRACE_EVENT1("webkit", "WebViewImpl::enterForceCompositingMode", "enter", enter);
-    settingsImpl()->setForceCompositingMode(enter);
-    if (enter) {
-        if (!m_page)
-            return;
-        LocalFrame* mainFrame = m_page->mainFrame();
-        if (!mainFrame)
-            return;
-        mainFrame->view()->updateCompositingLayersAfterStyleChange();
-    }
-}
-
 void WebViewImpl::paint(WebCanvas* canvas, const WebRect& rect)
 {
     // This should only be used when compositing is not being used for this
     // WebView, and it is painting into the recording of its parent.
     ASSERT(!isAcceleratedCompositingActive());
 
     double paintStart = currentTime();
     PageWidgetDelegate::paint(m_page.get(), pageOverlays(), canvas, rect, isTransparent() ? PageWidgetDelegate::Translucent : PageWidgetDelegate::Opaque);
     double paintEnd = currentTime();
     double pixelsPerSec = (rect.width * rect.height) / (paintEnd - paintStart);
@@ skipping 1832 matching lines @@
     m_client->didUpdateLayout();
 }
 
 void WebViewImpl::didChangeContentsSize()
 {
     m_pageScaleConstraintsSet.didChangeContentsSize(contentsSize(), pageScaleFactor());
 }
 
 void WebViewImpl::deviceOrPageScaleFactorChanged()
 {
-    if (pageScaleFactor() && pageScaleFactor() != 1)
-        enterForceCompositingMode(true);
     m_pageScaleConstraintsSet.setNeedsReset(false);
     updateLayerTreeViewport();
 }
 
 bool WebViewImpl::useExternalPopupMenus()
 {
     return shouldUseExternalPopupMenus;
 }
 
 void WebViewImpl::startDragging(LocalFrame* frame,
@@ skipping 202 matching lines @@
     blink::Platform::current()->histogramEnumeration("GPU.setIsAcceleratedCompositingActive", active * 2 + m_isAcceleratedCompositingActive, 4);
 
     if (m_isAcceleratedCompositingActive == active)
         return;
 
     if (!m_client)
         return;
 
     if (!active) {
         m_isAcceleratedCompositingActive = false;
-        // We need to finish all GL rendering before sending didDeactivateCompositor() to prevent
-        // flickering when compositing turns off. This is only necessary if we're not in
-        // force-compositing-mode.
-        if (m_layerTreeView && !page()->settings().forceCompositingMode())
-            m_layerTreeView->finishAllRendering();
         m_client->didDeactivateCompositor();
         if (!m_layerTreeViewCommitsDeferred
             && blink::Platform::current()->isThreadedCompositingEnabled()) {
             ASSERT(m_layerTreeView);
             // In threaded compositing mode, force compositing mode is always on so setIsAcceleratedCompositingActive(false)
             // means that we're transitioning to a new page. Suppress commits until WebKit generates invalidations so
             // we don't attempt to paint too early in the next page load.
             m_layerTreeView->setDeferCommits(true);
             m_layerTreeViewCommitsDeferred = true;
         }
@@ skipping 237 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