Cleanup and refactor RootScrollerController.

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

Index: third_party/WebKit/Source/core/page/scrolling/ViewportScrollCallback.cpp
diff --git a/third_party/WebKit/Source/core/page/scrolling/ViewportScrollCallback.cpp b/third_party/WebKit/Source/core/page/scrolling/ViewportScrollCallback.cpp
index 0c0e1d835db0954928d3ae657f22578fad853703..80b75379357df025adc310cf96c85d39a19e9d06 100644
--- a/third_party/WebKit/Source/core/page/scrolling/ViewportScrollCallback.cpp
+++ b/third_party/WebKit/Source/core/page/scrolling/ViewportScrollCallback.cpp
@@ -4,19 +4,116 @@
 
 #include "core/page/scrolling/ViewportScrollCallback.h"
 
+#include "core/frame/FrameHost.h"
+#include "core/frame/FrameView.h"
+#include "core/frame/RootFrameViewport.h"
+#include "core/frame/Settings.h"
+#include "core/frame/TopControls.h"
+#include "core/page/scrolling/OverscrollController.h"
 #include "core/page/scrolling/ScrollState.h"
+#include "platform/geometry/FloatSize.h"
 #include "platform/scroll/ScrollableArea.h"
 
 namespace blink {
 
-ScrollResult ViewportScrollCallback::performNativeScroll(
-    ScrollState& state, ScrollableArea& scroller)
+ViewportScrollCallback::ViewportScrollCallback(
+    TopControls* topControls,
+    OverscrollController* overscrollController,
+    RootFrameViewport& rootFrameViewport)
+    : m_topControls(topControls)
+    , m_overscrollController(overscrollController)
+    , m_rootFrameViewport(&rootFrameViewport)
 {
+}
+
+ViewportScrollCallback::~ViewportScrollCallback()
+{
+}
+
+DEFINE_TRACE(ViewportScrollCallback)
+{
+    visitor->trace(m_topControls);
+    visitor->trace(m_overscrollController);
+    visitor->trace(m_rootFrameViewport);
+    ScrollStateCallback::trace(visitor);
+}
+
+bool ViewportScrollCallback::shouldScrollTopControls(const FloatSize& delta,
+    ScrollGranularity granularity) const
+{
+    if (granularity != ScrollByPixel && granularity != ScrollByPrecisePixel)
+        return false;
+
+    if (!m_rootFrameViewport)
+        return false;
+
+    DoublePoint maxScroll = m_rootFrameViewport->maximumScrollPositionDouble();
+    DoublePoint scrollPosition = m_rootFrameViewport->scrollPositionDouble();
+
+    // Always give the delta to the top controls if the scroll is in
+    // the direction to show the top controls. If it's in the
+    // direction to hide the top controls, only give the delta to the
+    // top controls when the frame can scroll.
+    return delta.height() < 0 || scrollPosition.y() < maxScroll.y();
+}
+
+bool ViewportScrollCallback::scrollTopControls(ScrollState& state)
+{
+    // Scroll top controls.
+    if (m_topControls) {
+        if (state.isBeginning())
+            m_topControls->scrollBegin();
+
+        FloatSize delta(state.deltaX(), state.deltaY());
+        ScrollGranularity granularity =
+            ScrollGranularity(static_cast<int>(state.deltaGranularity()));
+        if (shouldScrollTopControls(delta, granularity)) {
+            FloatSize remainingDelta = m_topControls->scrollBy(delta);
+            FloatSize consumed = delta - remainingDelta;
+            state.consumeDeltaNative(consumed.width(), consumed.height());
+            return !consumed.isZero();
+        }
+    }
+
+    return false;
+}
+
+void ViewportScrollCallback::handleEvent(ScrollState* state)
+{
+    DCHECK(state);
+    if (!m_rootFrameViewport)
+        return;
+
+    bool topControlsDidScroll = scrollTopControls(*state);
+
+    ScrollResult result = performNativeScroll(*state);
+
+    // We consider top controls movement to be scrolling.
+    result.didScrollY |= topControlsDidScroll;
+
+    // Handle Overscroll.
+    if (m_overscrollController) {
+        FloatPoint position(state->positionX(), state->positionY());
+        FloatSize velocity(state->velocityX(), state->velocityY());
+        m_overscrollController->handleOverscroll(result, position, velocity);
+    }
+}
+
+void ViewportScrollCallback::setScroller(ScrollableArea* scroller)
+{
+    DCHECK(scroller);
+    m_rootFrameViewport->setLayoutViewport(*scroller);
+}
+
+ScrollResult ViewportScrollCallback::performNativeScroll(ScrollState& state)
+{
+    DCHECK(m_rootFrameViewport);
+
     FloatSize delta(state.deltaX(), state.deltaY());
     ScrollGranularity granularity =
         ScrollGranularity(static_cast<int>(state.deltaGranularity()));
 
-    ScrollResult result = scroller.userScroll(granularity, delta);
+    ScrollResult result = m_rootFrameViewport->userScroll(granularity, delta);
 
     // The viewport consumes everything.
     // TODO(bokan): This isn't actually consuming everything but doing so breaks