Fix border radius on composited children.

third_party/WebKit/Source/platform/graphics/paint/DrawingRecorder.cpp

Index: third_party/WebKit/Source/platform/graphics/paint/DrawingRecorder.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/paint/DrawingRecorder.cpp b/third_party/WebKit/Source/platform/graphics/paint/DrawingRecorder.cpp
index a6011c9c7fa76775fe12ddf65368f260085e1f96..576e0e321ee334f2b6c79539fed2f7a4261c118a 100644
--- a/third_party/WebKit/Source/platform/graphics/paint/DrawingRecorder.cpp
+++ b/third_party/WebKit/Source/platform/graphics/paint/DrawingRecorder.cpp
@@ -82,8 +82,16 @@ DrawingRecorder::~DrawingRecorder() {
   sk_sp<const SkPicture> picture = m_context.endRecording();
 
 #if DCHECK_IS_ON()
+  // The check for DisplayItem::kPaintPhaseMax works because kPaintPhaseMax is
+  // PaintPhase::PaintPhaseClippingMask. But we can't use the latter because
+  // it lives in core. The check is needed because a child that needs a clipping
+  // mask needs it regardless of whether the child itself draws content,
+  // and that mask's DrawingRecorder has a non-empty picture even if the child
+  // itself draws no content.
   if (!RuntimeEnabledFeatures::slimmingPaintStrictCullRectClippingEnabled() &&
       !m_context.getPaintController().isForSkPictureBuilder() &&
+      m_displayItemType !=

[chrishtr, 2016/12/09 23:09:34]

I thought about this and tried out a few alternatives for avoiding this
situation,
but could find nothing simple that would work better than the current
implementation
of painting masks.

However, rather than this method of avoiding an assert, I would like this one:

return false from paintedOutputOfObjectHasNoEffectRegardlessOfSize() if 
layer()->compositingState() == PaintsIntoOwnBacking.

[Stephen Chennney, 2016/12/12 19:18:03]

Done.

+          DisplayItem::paintPhaseToDrawingType(DisplayItem::kPaintPhaseMax) &&
       m_displayItemClient.paintedOutputOfObjectHasNoEffectRegardlessOfSize()) {
     DCHECK_EQ(0, picture->approximateOpCount())
         << m_displayItemClient.debugName();