Don't try to paint graphics layers inside throttled frames

third_party/WebKit/Source/core/paint/FramePainter.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 "core/paint/FramePainter.h"
 
 #include "core/editing/markers/DocumentMarkerController.h"
 #include "core/fetch/MemoryCache.h"
 #include "core/frame/FrameView.h"
 #include "core/inspector/InspectorInstrumentation.h"
@@ skipping 77 matching lines @@
         ClipRecorder recorder(context, *frameView().layoutView(), DisplayItem::ClipFrameScrollbars, LayoutRect(IntPoint(), visibleAreaWithScrollbars.size()));
 
         paintScrollbars(context, scrollViewDirtyRect);
     }
 }
 
 void FramePainter::paintContents(GraphicsContext& context, const GlobalPaintFlags globalPaintFlags, const IntRect& rect)
 {
     Document* document = frameView().frame().document();
 
+    if (frameView().shouldThrottleRendering())
+        return;
+
 #ifndef NDEBUG
     bool fillWithRed;
     if (document->printing())
         fillWithRed = false; // Printing, don't fill with red (can't remember why).
     else if (frameView().frame().owner())
         fillWithRed = false; // Subframe, don't fill with red.
     else if (frameView().isTransparent())
         fillWithRed = false; // Transparent, don't fill with red.
     else if (globalPaintFlags & GlobalPaintSelectionOnly)
         fillWithRed = false; // Selections are transparent, don't fill with red.
     else
         fillWithRed = true;
 
     if (fillWithRed && !LayoutObjectDrawingRecorder::useCachedDrawingIfPossible(context, *frameView().layoutView(), DisplayItem::DebugRedFill)) {
         IntRect contentRect(IntPoint(), frameView().contentsSize());
         LayoutObjectDrawingRecorder drawingRecorder(context, *frameView().layoutView(), DisplayItem::DebugRedFill, contentRect);
     }
 #endif
 
     LayoutView* layoutView = frameView().layoutView();
     if (!layoutView) {
         DLOG(ERROR) << "called FramePainter::paint with nil layoutObject";
         return;
     }
 
-    if (!frameView().shouldThrottleRendering()) {
-        RELEASE_ASSERT(!frameView().needsLayout());
-        ASSERT(document->lifecycle().state() >= DocumentLifecycle::CompositingClean);
-    }
+    RELEASE_ASSERT(!frameView().needsLayout());
+    ASSERT(document->lifecycle().state() >= DocumentLifecycle::CompositingClean);
 
     TRACE_EVENT1("devtools.timeline", "Paint", "data", InspectorPaintEvent::data(layoutView, LayoutRect(rect), 0));
 
     bool isTopLevelPainter = !s_inPaintContents;
     s_inPaintContents = true;
 
     FontCachePurgePreventer fontCachePurgePreventer;
 
     // TODO(jchaffraix): GlobalPaintFlags should be const during a paint
     // phase. Thus we should set this flag upfront (crbug.com/510280).
     GlobalPaintFlags localPaintFlags = globalPaintFlags;
     if (document->printing())
         localPaintFlags |= GlobalPaintFlattenCompositingLayers | GlobalPaintPrinting;
 
     PaintLayer* rootLayer = layoutView->layer();
 
 #if ENABLE(ASSERT)
-    if (!frameView().shouldThrottleRendering())
-        layoutView->assertSubtreeIsLaidOut();
+    layoutView->assertSubtreeIsLaidOut();
     LayoutObject::SetLayoutNeededForbiddenScope forbidSetNeedsLayout(*rootLayer->layoutObject());
 #endif
 
     PaintLayerPainter layerPainter(*rootLayer);
 
     float deviceScaleFactor = blink::deviceScaleFactor(rootLayer->layoutObject()->frame());
     context.setDeviceScaleFactor(deviceScaleFactor);
 
     layerPainter.paint(context, LayoutRect(rect), localPaintFlags);
 
@@ skipping 55 matching lines @@
     bar.paint(context, CullRect(rect));
 }
 
 const FrameView& FramePainter::frameView()
 {
     ASSERT(m_frameView);
     return *m_frameView;
 }
 
 } // namespace blink