Disable clipping on root scroller's ancestors.

third_party/WebKit/Source/core/page/scrolling/TopDocumentRootScrollerController.h

Index: third_party/WebKit/Source/core/page/scrolling/TopDocumentRootScrollerController.h
diff --git a/third_party/WebKit/Source/core/page/scrolling/TopDocumentRootScrollerController.h b/third_party/WebKit/Source/core/page/scrolling/TopDocumentRootScrollerController.h
index 2c581383feb436ac216367a2433e6cf9b506fdd2..40273c5b331703a8b31090ccc5b89cf1caf10c93 100644
--- a/third_party/WebKit/Source/core/page/scrolling/TopDocumentRootScrollerController.h
+++ b/third_party/WebKit/Source/core/page/scrolling/TopDocumentRootScrollerController.h
@@ -53,6 +53,9 @@ public:
     // Returns the GraphicsLayer for the global root scroller.
     GraphicsLayer* rootScrollerLayer() override;
 
+    // Returns the Element that's the global root scroller.
+    Element* globalRootScroller() const;
+
 protected:
     TopDocumentRootScrollerController(Document&);
 
@@ -70,6 +73,8 @@ private:
     // appropriate state changes are made if it changes.
     void updateGlobalRootScroller();
 
+    void setNeedsCompositingInputsUpdateOnGlobalRootScroller();
+
     // The apply-scroll callback that moves top controls and produces
     // overscroll effects. This class makes sure this callback is set on the
     // appropriate root scroller element.