Split RootScrollerController into top-document and child-document classes

third_party/WebKit/Source/core/dom/Document.cpp

Index: third_party/WebKit/Source/core/dom/Document.cpp
diff --git a/third_party/WebKit/Source/core/dom/Document.cpp b/third_party/WebKit/Source/core/dom/Document.cpp
index 7662498c05a45de464e797597910fbd087804d15..e6ab2c265e1f09106422611696ef01228bfff4aa 100644
--- a/third_party/WebKit/Source/core/dom/Document.cpp
+++ b/third_party/WebKit/Source/core/dom/Document.cpp
@@ -207,7 +207,7 @@
 #include "core/page/scrolling/ScrollStateCallback.h"
 #include "core/page/scrolling/ScrollingCoordinator.h"
 #include "core/page/scrolling/SnapCoordinator.h"
-#include "core/page/scrolling/ViewportScrollCallback.h"
+#include "core/page/scrolling/TopDocumentRootScrollerController.h"
 #include "core/svg/SVGDocumentExtensions.h"
 #include "core/svg/SVGScriptElement.h"
 #include "core/svg/SVGTitleElement.h"
@@ -473,7 +473,11 @@ Document::Document(const DocumentInit& initializer, DocumentClassFlags documentC
         m_fetcher = ResourceFetcher::create(nullptr);
     }
 
-    m_rootScrollerController = RootScrollerController::create(*this);
+    // TODO(bokan): RootScrollerController currently assumes we have an m_frame
+    // in checks to isInMainFrame.

[tdresser, 2016/08/25 14:59:21]

I don't quite follow this TODO.

[bokan, 2016/08/25 15:14:13]

Ah, yah, this was added pre-split so I've updated it to make more sense. The
issue is that we can actually initialize a Document without an m_frame which
will now assume that we're in a child document which isn't necessarily true.
This should become moot when I move make TopDocumentRootScroller owned by a
page-level object.

[tdresser, 2016/08/25 15:18:11]

Should this TODO have a bug?

+    m_rootScrollerController = isInMainFrame()
+        ? TopDocumentRootScrollerController::create(*this)
+        : RootScrollerController::create(*this);
 
     // We depend on the url getting immediately set in subframes, but we
     // also depend on the url NOT getting immediately set in opened windows.