Throttle rendering pipeline for invisible iframes

Source/core/paint/DeprecatedPaintLayerPainter.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/DeprecatedPaintLayerPainter.h"
 
 #include "core/frame/Settings.h"
 #include "core/layout/ClipPathOperation.h"
 #include "core/layout/LayoutBlock.h"
+#include "core/layout/LayoutFrame.h"
 #include "core/layout/LayoutView.h"
 #include "core/layout/svg/LayoutSVGResourceClipper.h"
 #include "core/page/Page.h"
 #include "core/paint/CompositingRecorder.h"
 #include "core/paint/DeprecatedPaintLayer.h"
 #include "core/paint/FilterPainter.h"
 #include "core/paint/LayerClipRecorder.h"
 #include "core/paint/LayerFixedPositionRecorder.h"
 #include "core/paint/PaintInfo.h"
 #include "core/paint/SVGClipPainter.h"
@@ skipping 15 matching lines @@
 {
     // Avoid painting descendants of the root layer when stylesheets haven't loaded. This eliminates FOUC.
     // It's ok not to draw, because later on, when all the stylesheets do load, updateStyleSelector on the Document
     // will do a full paintInvalidationForWholeLayoutObject().
     if (layer->layoutObject()->document().didLayoutWithPendingStylesheets() && !layer->isRootLayer() && !layer->layoutObject()->isDocumentElement())
         return true;
 
     return false;
 }
 
+static bool isThrottledFrameView(const LayoutObject* layoutObject)
+{
+    if (!layoutObject->isFrame())
+        return false;
+    const LayoutFrame* frame = toLayoutFrame(layoutObject);
+    if (!frame->widget()->isFrameView())
+        return false;
+    const FrameView* frameView = toFrameView(frame->widget());
+    return frameView->shouldThrottleRenderingPipeline();
+}
+
 void DeprecatedPaintLayerPainter::paint(GraphicsContext* context, const LayoutRect& damageRect, const GlobalPaintFlags globalPaintFlags, LayoutObject* paintingRoot, PaintLayerFlags paintFlags)
 {
     DeprecatedPaintLayerPaintingInfo paintingInfo(&m_paintLayer, LayoutRect(enclosingIntRect(damageRect)), globalPaintFlags, LayoutSize(), paintingRoot);
     if (shouldPaintLayerInSoftwareMode(globalPaintFlags, paintFlags))
         paintLayer(context, paintingInfo, paintFlags);
 }
 
 static ShouldRespectOverflowClip shouldRespectOverflowClip(PaintLayerFlags paintFlags, const LayoutObject* layoutObject)
 {
     return (paintFlags & PaintLayerPaintingOverflowContents || (paintFlags & PaintLayerPaintingChildClippingMaskPhase && layoutObject->hasClipPath())) ? IgnoreOverflowClip : RespectOverflowClip;
@@ skipping 17 matching lines @@
         ASSERT(!m_paintLayer.needsRepaint());
         return;
     }
 
     bool needsRepaint = m_paintLayer.needsRepaint();
     m_paintLayer.clearNeedsRepaint();
 
     if (shouldSuppressPaintingLayer(&m_paintLayer))
         return;
 
+    if (isThrottledFrameView(m_paintLayer.layoutObject()))

[chrishtr, 2015/09/04 17:32:04]

Add TODO here and below about subsequence caching.

[Sami, 2015/09/07 17:27:17]

Done.

+        return;
+
     // If this layer is totally invisible then there is nothing to paint.
     if (!m_paintLayer.layoutObject()->opacity() && !m_paintLayer.layoutObject()->hasBackdropFilter())
         return;
 
     if (!needsRepaint && SubsequenceRecorder::useCachedSubsequenceIfPossible(*context, m_paintLayer))
         return;
     SubsequenceRecorder subsequenceRecorder(*context, m_paintLayer);
 
     if (m_paintLayer.paintsWithTransparency(paintingInfo.globalPaintFlags()))
         paintFlags |= PaintLayerHaveTransparency;
@@ skipping 103 matching lines @@
     // foreground phase. Since scrolled contents are moved by paint invalidation in this
     // case, the outline won't get 'dragged along'.
     bool shouldPaintOutline = isSelfPaintingLayer && !isPaintingOverlayScrollbars
         && ((isPaintingScrollingContent && isPaintingCompositedBackground)
         || (!isPaintingScrollingContent && isPaintingCompositedForeground));
     bool shouldPaintContent = m_paintLayer.hasVisibleContent() && isSelfPaintingLayer && !isPaintingOverlayScrollbars;
 
     if (paintFlags & PaintLayerPaintingRootBackgroundOnly && !m_paintLayer.layoutObject()->isLayoutView() && !m_paintLayer.layoutObject()->isDocumentElement())
         return;
 
+    if (isThrottledFrameView(m_paintLayer.layoutObject()))
+        return;
+
     // Ensure our lists are up-to-date.
     m_paintLayer.stackingNode()->updateLayerListsIfNeeded();
 
     LayoutPoint offsetFromRoot;
     m_paintLayer.convertToLayerCoords(paintingInfo.rootLayer, offsetFromRoot);
 
     if (m_paintLayer.compositingState() == PaintsIntoOwnBacking)
         offsetFromRoot.move(m_paintLayer.subpixelAccumulation());
     else
         offsetFromRoot.move(paintingInfo.subPixelAccumulation);
@@ skipping 394 matching lines @@
     if (!m_paintLayer.containsDirtyOverlayScrollbars())
         return;
 
     DeprecatedPaintLayerPaintingInfo paintingInfo(&m_paintLayer, LayoutRect(enclosingIntRect(damageRect)), paintFlags, LayoutSize(), paintingRoot);
     paintLayer(context, paintingInfo, PaintLayerPaintingOverlayScrollbars);
 
     m_paintLayer.setContainsDirtyOverlayScrollbars(false);
 }
 
 } // namespace blink