LayoutFullScreen::m_placeholder is LayoutBlockFlow.

third_party/WebKit/Source/core/layout/LayoutFullScreen.cpp

Index: third_party/WebKit/Source/core/layout/LayoutFullScreen.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutFullScreen.cpp b/third_party/WebKit/Source/core/layout/LayoutFullScreen.cpp
index 8be0566be3e9e9280697df64b01f987efe3ea3d4..9d8802674bd23e2c141bd0c45cd17cd60d8d0172 100644
--- a/third_party/WebKit/Source/core/layout/LayoutFullScreen.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutFullScreen.cpp
@@ -54,7 +54,7 @@ private:
 
 void LayoutFullScreenPlaceholder::willBeDestroyed()
 {
-    m_owner->setPlaceholder(nullptr);
+    m_owner->resetPlaceholder();
     LayoutBlockFlow::willBeDestroyed();
 }
 
@@ -181,11 +181,6 @@ void LayoutFullScreen::unwrapLayoutObject()
     destroy();
 }
 
-void LayoutFullScreen::setPlaceholder(LayoutBlock* placeholder)
-{
-    m_placeholder = placeholder;
-}
-
 void LayoutFullScreen::createPlaceholder(PassRefPtr<ComputedStyle> style, const LayoutRect& frameRect)
 {
     if (style->width().isAuto())