Throttle rendering pipeline for invisible iframes

Source/core/paint/ViewPainter.cpp

 // Copyright 2014 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 "core/paint/ViewPainter.h"
 
 #include "core/frame/FrameView.h"
 #include "core/frame/Settings.h"
 #include "core/layout/LayoutBox.h"
 #include "core/layout/LayoutView.h"
 #include "core/paint/BlockPainter.h"
 #include "core/paint/BoxPainter.h"
 #include "core/paint/DeprecatedPaintLayer.h"
 #include "core/paint/LayoutObjectDrawingRecorder.h"
 #include "core/paint/PaintInfo.h"
 #include "platform/RuntimeEnabledFeatures.h"
 
 namespace blink {
 
 void ViewPainter::paint(const PaintInfo& paintInfo, const LayoutPoint& paintOffset)
 {
     // If we ever require layout but receive a paint anyway, something has gone horribly wrong.
     ASSERT(!m_layoutView.needsLayout());
     // LayoutViews should never be called to paint with an offset not on device pixels.
     ASSERT(LayoutPoint(IntPoint(paintOffset.x(), paintOffset.y())) == paintOffset);
 
+    const FrameView* frameView = m_layoutView.frameView();
+    if (frameView->shouldThrottleRenderingPipeline())
+        return;
+
     m_layoutView.paintObject(paintInfo, paintOffset);
     BlockPainter(m_layoutView).paintOverflowControlsIfNeeded(paintInfo, paintOffset);
 }
 
 void ViewPainter::paintBoxDecorationBackground(const PaintInfo& paintInfo)
 {
     if (!paintInfo.shouldPaintWithinRoot(&m_layoutView))
         return;
 
     if (paintInfo.skipRootBackground())
@@ skipping 103 matching lines @@
         ASSERT((*it)->clip() == BorderFillBox);
         BoxPainter::paintFillLayerExtended(m_layoutView, paintInfo, Color(), **it, LayoutRect(paintRect), BackgroundBleedNone);
     }
     context.restore();
 
     if (shouldDrawBackgroundInSeparateBuffer)
         context.endLayer();
 }
 
 } // namespace blink