Fix partial painting with render pipeline throttling

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 93 matching lines @@
         LayoutObjectDrawingRecorder drawingRecorder(context, *frameView().layoutView(), DisplayItem::DebugRedFill, contentRect, LayoutPoint());
     }
 #endif
 
     LayoutView* layoutView = frameView().layoutView();
     if (!layoutView) {
         WTF_LOG_ERROR("called FramePainter::paint with nil layoutObject");
         return;
     }
 
-    RELEASE_ASSERT(!frameView().needsLayout());
-    ASSERT(document->lifecycle().state() >= DocumentLifecycle::CompositingClean);
+    if (!frameView().shouldThrottleRendering()) {
+        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;
 
     ASSERT(!frameView().isPainting());
     frameView().setIsPainting(true);
 
     PaintLayer* rootLayer = layoutView->layer();
 
 #if ENABLE(ASSERT)
-    layoutView->assertSubtreeIsLaidOut();
+    if (!frameView().shouldThrottleRendering())
+        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 57 matching lines @@
     bar.paint(context, CullRect(rect));
 }
 
 const FrameView& FramePainter::frameView()
 {
     ASSERT(m_frameView);
     return *m_frameView;
 }
 
 } // namespace blink