Use float for scroll offset.

third_party/WebKit/Source/core/frame/FrameView.h

Index: third_party/WebKit/Source/core/frame/FrameView.h
diff --git a/third_party/WebKit/Source/core/frame/FrameView.h b/third_party/WebKit/Source/core/frame/FrameView.h
index daa3e3c5951b8bf1c148ffb8ed7709b4f8e257fc..93b385cbcd00ecd85a029f8c063faed6901af34f 100644
--- a/third_party/WebKit/Source/core/frame/FrameView.h
+++ b/third_party/WebKit/Source/core/frame/FrameView.h
@@ -194,11 +194,7 @@ class CORE_EXPORT FrameView final
   IntSize inputEventsOffsetForEmulation() const;
   void setInputEventsTransformForEmulation(const IntSize&, float);
 
-  void setScrollPosition(const DoublePoint&,
-                         ScrollType,
-                         ScrollBehavior = ScrollBehaviorInstant) override;
   void didChangeScrollOffset();
-
   void didUpdateElasticOverscroll();
 
   void viewportSizeChanged(bool widthChanged, bool heightChanged);
@@ -292,7 +288,7 @@ class CORE_EXPORT FrameView final
   // Updates the fragment anchor element based on URL's fragment identifier.
   // Updates corresponding ':target' CSS pseudo class on the anchor element.
   // If |UrlFragmentScroll| is passed in then makes the anchor element
-  // focused and also visible by scrolling to it. The scroll position is
+  // focused and also visible by scrolling to it. The scroll offset is
   // maintained during the frame loading process.
   void processUrlFragment(const KURL&, UrlFragmentBehavior = UrlFragmentScroll);
   void clearFragmentAnchor();
@@ -401,7 +397,7 @@ class CORE_EXPORT FrameView final
     return IntSize(0, ceilf(m_topControlsViewportAdjustment));
   }
 
-  IntPoint maximumScrollPosition() const override;
+  IntSize maximumScrollOffsetInt() const override;
 
   // ScrollableArea interface
   void getTickmarks(Vector<IntRect>&) const override;
@@ -512,25 +508,19 @@ class CORE_EXPORT FrameView final
   int contentsWidth() const { return contentsSize().width(); }
   int contentsHeight() const { return contentsSize().height(); }
 
-  // Functions for querying the current scrolled position (both as a point, a size, or as individual X and Y values).
-  // Be careful in using the Double version scrollPositionDouble() and scrollOffsetDouble(). They are meant to be
-  // used to communicate the fractional scroll position/offset with chromium compositor which can do sub-pixel positioning.
-  // Do not call these if the scroll position/offset is used in Blink for positioning. Use the Int version instead.
-  IntPoint scrollPosition() const override {
-    return visibleContentRect().location();
-  }
-  DoublePoint scrollPositionDouble() const override { return m_scrollPosition; }
-  IntSize scrollOffset() const {
+  // Functions for querying the current scrolled offset (both as a point, a size, or as individual X and Y values).
+  // Be careful in using the Float version scrollOffset() and scrollOffset(). They are meant to be
+  // used to communicate the fractional scroll offset with chromium compositor which can do sub-pixel positioning.
+  // Do not call these if the scroll offset is used in Blink for positioning. Use the Int version instead.
+  IntSize scrollOffsetInt() const override {
     return toIntSize(visibleContentRect().location());
-  }  // Gets the scrolled position as an IntSize. Convenient for adding to other sizes.
-  DoubleSize scrollOffsetDouble() const {
-    return DoubleSize(m_scrollPosition.x(), m_scrollPosition.y());
   }
-  DoubleSize pendingScrollDelta() const { return m_pendingScrollDelta; }
-  IntPoint minimumScrollPosition()
-      const override;  // The minimum position we can be scrolled to.
-  int scrollX() const { return scrollPosition().x(); }
-  int scrollY() const { return scrollPosition().y(); }
+  ScrollOffset scrollOffset() const override { return m_scrollOffset; }
+  ScrollOffset pendingScrollDelta() const { return m_pendingScrollDelta; }
+  IntSize minimumScrollOffsetInt()
+      const override;  // The minimum offset we can be scrolled to.
+  int scrollX() const { return scrollOffsetInt().width(); }
+  int scrollY() const { return scrollOffsetInt().height(); }
 
   // Scroll the actual contents of the view (either blitting or invalidating as needed).
   void scrollContents(const IntSize& scrollDelta);
@@ -764,7 +754,7 @@ class CORE_EXPORT FrameView final
  private:
   explicit FrameView(LocalFrame*);
 
-  void updateScrollPosition(const DoublePoint&, ScrollType) override;
+  void updateScrollOffset(const ScrollOffset&, ScrollType) override;
 
   void updateLifecyclePhasesInternal(
       DocumentLifecycle::LifecycleState targetState);
@@ -786,7 +776,7 @@ class CORE_EXPORT FrameView final
 
   void clearLayoutSubtreeRootsAndMarkContainingBlocks();
 
-  // Called when our frame rect changes (or the rect/scroll position of an ancestor changes).
+  // Called when our frame rect changes (or the rect/scroll offset of an ancestor changes).
   void frameRectsChanged() override;
 
   bool contentsInCompositedLayer() const;
@@ -831,7 +821,7 @@ class CORE_EXPORT FrameView final
   void didScrollTimerFired(TimerBase*);
 
   void updateLayersAndCompositingAfterScrollIfNeeded(
-      const DoubleSize& scrollDelta);
+      const ScrollOffset& scrollDelta);
 
   static bool computeCompositedSelection(LocalFrame&, CompositedSelection&);
   void updateCompositedSelectionIfNeeded();
@@ -858,7 +848,7 @@ class CORE_EXPORT FrameView final
 
   bool adjustScrollbarExistence(ComputeScrollbarExistenceOption = FirstPass);
   void adjustScrollbarOpacity();
-  void adjustScrollPositionFromUpdateScrollbars();
+  void adjustScrollOffsetFromUpdateScrollbars();
   bool visualViewportSuppliesScrollbars() const;
 
   bool isFrameViewScrollbar(const Widget* child) const {
@@ -988,8 +978,8 @@ class CORE_EXPORT FrameView final
 
   ChildrenWidgetSet m_children;
 
-  DoubleSize m_pendingScrollDelta;
-  DoublePoint m_scrollPosition;
+  ScrollOffset m_pendingScrollDelta;
+  ScrollOffset m_scrollOffset;
   IntSize m_contentsSize;
 
   int m_scrollbarsAvoidingResizer;