Fixed up root scroller API to be more webby

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 f05f277465d432d8b9a6bc5a7f928ba1b961aeee..639c887a9fe110a66b4c16895ca97df321e956cb 100644
--- a/third_party/WebKit/Source/core/dom/Document.cpp
+++ b/third_party/WebKit/Source/core/dom/Document.cpp
@@ -194,6 +194,7 @@
 #include "core/page/PointerLockController.h"
 #include "core/page/scrolling/RootScroller.h"
 #include "core/page/scrolling/ScrollingCoordinator.h"
+#include "core/page/scrolling/ViewportScrollCallback.h"
 #include "core/svg/SVGDocumentExtensions.h"
 #include "core/svg/SVGScriptElement.h"
 #include "core/svg/SVGTitleElement.h"
@@ -473,6 +474,13 @@ Document::Document(const DocumentInit& initializer, DocumentClassFlags documentC
         m_fetcher = ResourceFetcher::create(nullptr);
     }
 
+    ViewportScrollCallback* applyScroll = nullptr;
+    if (isInMainFrame()) {
+        applyScroll = RootScroller::createViewportApplyScroll(
+            frameHost()->topControls(), frameHost()->overscrollController());
+    }
+    m_rootScroller = RootScroller::create(*this, applyScroll);

[esprehn, 2016/05/11 17:37:05]

we should rename RootScroller to something like RootScrollController or
something. It's confusing that setRootScroller takes an Element, and the
RootScroller object is something else.

[bokan, 2016/06/02 15:49:55]

Acknowledged.

+
     // We depend on the url getting immediately set in subframes, but we
     // also depend on the url NOT getting immediately set in opened windows.
     // See fast/dom/early-frame-url.html
@@ -596,52 +604,20 @@ void Document::childrenChanged(const ChildrenChange& change)
 
 void Document::setRootScroller(Element* newScroller, ExceptionState& exceptionState)
 {
-    DCHECK(newScroller);
-
-    if (!frame() || !frame()->isMainFrame()) {
-        exceptionState.throwDOMException(
-            WrongDocumentError,
-            "Root scroller can only be set on the top window's document.");
-        return;
-    }
-
-    if (newScroller->document() != this) {
-        exceptionState.throwDOMException(
-            WrongDocumentError,
-            "Element isn't in this document.");
-        return;
-    }
-
-    FrameHost* host = frameHost();
-    if (!host)
-        return;
-
-    RootScroller* rootScroller = host->rootScroller();
-    DCHECK(rootScroller);
-
-    if (!rootScroller->set(*newScroller)) {
-        exceptionState.throwDOMException(
-            InvalidStateError,
-            "Element cannot be set as root scroller. Must be block or iframe.");
-    }
+    m_rootScroller->set(newScroller);
 }
 
-Element* Document::rootScroller()
+Element* Document::rootScroller() const
 {
-    // TODO(bokan): Should child frames return the documentElement or nullptr?
-    if (!isInMainFrame())
-        return documentElement();
-
-    FrameHost* host = frameHost();
-    if (!host)
-        return nullptr;
-
-    RootScroller* rootScroller = host->rootScroller();
-    DCHECK(rootScroller);
+    return m_rootScroller->get();
+}
 
-    updateLayoutIgnorePendingStylesheets();
+bool Document::isEffectiveRootScroller(const Element* element) const
+{
+    if (!element)
+        return false;
 
-    return rootScroller->get();
+    return m_rootScroller->effectiveRootScroller() == element;
 }
 
 bool Document::isInMainFrame() const
@@ -1930,10 +1906,7 @@ void Document::layoutUpdated()
             m_documentTiming.markFirstLayout();
     }
 
-    if (isInMainFrame() && frameHost()) {
-        DCHECK(frameHost()->rootScroller());
-        frameHost()->rootScroller()->didUpdateTopDocumentLayout();
-    }
+    m_rootScroller->didUpdateLayout();
 }
 
 void Document::setNeedsFocusedElementCheck()
@@ -5915,6 +5888,7 @@ DEFINE_TRACE(Document)
     visitor->trace(m_hoverNode);
     visitor->trace(m_activeHoverElement);
     visitor->trace(m_documentElement);
+    visitor->trace(m_rootScroller);
     visitor->trace(m_titleElement);
     visitor->trace(m_axObjectCache);
     visitor->trace(m_markers);