Clarify the size of a document view (a.k.a layout size) that causes FrameView to emit the resize ev…

Source/core/platform/ScrollView.cpp

Index: Source/core/platform/ScrollView.cpp
diff --git a/Source/core/platform/ScrollView.cpp b/Source/core/platform/ScrollView.cpp
index 02fd24e5640257213b8e784a2353a7870f6221c2..141cf8afb0194d5568e4d68368d5ff934221544f 100644
--- a/Source/core/platform/ScrollView.cpp
+++ b/Source/core/platform/ScrollView.cpp
@@ -219,7 +219,20 @@ IntRect ScrollView::visibleContentRect(VisibleContentRectIncludesScrollbars scol
 
 IntSize ScrollView::layoutSize() const
 {
-    return m_fixedLayoutSize.isEmpty() || !m_useFixedLayout ? unscaledVisibleContentSize(ExcludeScrollbars) : m_fixedLayoutSize;
+    if (m_useFixedLayout) {
+        ASSERT(!m_fixedLayoutSize.isEmpty());
+        return m_fixedLayoutSize;
+    }
+    return unscaledVisibleContentSize(ExcludeScrollbars);
+}
+
+IntSize ScrollView::layoutSizeIncludingScrollbars() const
+{
+    if (m_useFixedLayout) {
+        ASSERT(!m_fixedLayoutSize.isEmpty());
+        return m_fixedLayoutSize;
+    }
+    return unscaledVisibleContentSize(IncludeScrollbars);
 }
 
 IntSize ScrollView::fixedLayoutSize() const