Make ViewportScrollCallback an interface and add child and root classes

third_party/WebKit/Source/core/page/scrolling/RootViewportScrollCallback.cpp

Index: third_party/WebKit/Source/core/page/scrolling/RootViewportScrollCallback.cpp
diff --git a/third_party/WebKit/Source/core/page/scrolling/ViewportScrollCallback.cpp b/third_party/WebKit/Source/core/page/scrolling/RootViewportScrollCallback.cpp
similarity index 86%
rename from third_party/WebKit/Source/core/page/scrolling/ViewportScrollCallback.cpp
rename to third_party/WebKit/Source/core/page/scrolling/RootViewportScrollCallback.cpp
index f8cc13a7ff8d3c9b0a824568832561bc51bfe749..d5b0de9a314fa2349b1252e1bb4a0e6a1eaaabdd 100644
--- a/third_party/WebKit/Source/core/page/scrolling/ViewportScrollCallback.cpp
+++ b/third_party/WebKit/Source/core/page/scrolling/RootViewportScrollCallback.cpp
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "core/page/scrolling/ViewportScrollCallback.h"
+#include "core/page/scrolling/RootViewportScrollCallback.h"
 
 #include "core/frame/FrameHost.h"
 #include "core/frame/FrameView.h"
@@ -15,26 +15,26 @@
 
 namespace blink {
 
-ViewportScrollCallback::ViewportScrollCallback(
+RootViewportScrollCallback::RootViewportScrollCallback(
     TopControls* topControls, OverscrollController* overscrollController)
     : m_topControls(topControls)
     , m_overscrollController(overscrollController)
 {
 }
 
-ViewportScrollCallback::~ViewportScrollCallback()
+RootViewportScrollCallback::~RootViewportScrollCallback()
 {
 }
 
-DEFINE_TRACE(ViewportScrollCallback)
+DEFINE_TRACE(RootViewportScrollCallback)
 {
     visitor->trace(m_topControls);
     visitor->trace(m_overscrollController);
     visitor->trace(m_scroller);
-    ScrollStateCallback::trace(visitor);
+    ViewportScrollCallback::trace(visitor);
 }
 
-bool ViewportScrollCallback::shouldScrollTopControls(const FloatSize& delta,
+bool RootViewportScrollCallback::shouldScrollTopControls(const FloatSize& delta,
     ScrollGranularity granularity) const
 {
     if (granularity != ScrollByPixel && granularity != ScrollByPrecisePixel)
@@ -53,7 +53,7 @@ bool ViewportScrollCallback::shouldScrollTopControls(const FloatSize& delta,
     return delta.height() < 0 || scrollPosition.y() < maxScroll.y();
 }
 
-void ViewportScrollCallback::handleEvent(ScrollState* state)
+void RootViewportScrollCallback::handleEvent(ScrollState* state)
 {
     FloatSize delta(state->deltaX(), state->deltaY());
     ScrollGranularity granularity =
@@ -96,7 +96,7 @@ void ViewportScrollCallback::handleEvent(ScrollState* state)
         state->deltaY() - result.unusedScrollDeltaY);
 }
 
-void ViewportScrollCallback::setScroller(ScrollableArea* scroller)
+void RootViewportScrollCallback::setScroller(ScrollableArea* scroller)
 {
     m_scroller = scroller;
 }