Adds scroll position/scale emulation to DevTools.

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 7e5be60fe9195575dd4c54ea41132eb19df2d506..a4647978dc08a2700fa3424a50577f17ce8a59bb 100644
--- a/third_party/WebKit/Source/core/frame/FrameView.h
+++ b/third_party/WebKit/Source/core/frame/FrameView.h
@@ -78,6 +78,7 @@ class LayoutScrollbarPart;
 class LayoutView;
 class PaintInvalidationState;
 class Page;
+class ScrollAndScaleEmulator;
 class ScrollingCoordinator;
 class TracedValue;
 struct AnnotatedRegionValue;
@@ -191,6 +192,9 @@ public:
 
     void setScrollPosition(const DoublePoint&, ScrollType, ScrollBehavior = ScrollBehaviorInstant) override;
 
+    // Override the scroll position with values from the emulator. Passing |nullptr| clears override.
+    void setScrollAndScaleEmulator(ScrollAndScaleEmulator*);
+
     void didUpdateElasticOverscroll();
 
     void viewportSizeChanged(bool widthChanged, bool heightChanged);
@@ -762,6 +766,10 @@ private:
 
     ScrollingCoordinator* scrollingCoordinator() const;
 
+    // Calculate the physical minimum/maximum scroll positions without any overrides applied.
+    IntPoint calculateMinimumScrollPosition() const;
+    IntPoint calculateMaximumScrollPosition() const;
+
     void prepareLayoutAnalyzer();
     std::unique_ptr<TracedValue> analyzerCounters();
 
@@ -879,6 +887,8 @@ private:
     DoublePoint m_scrollPosition;
     IntSize m_contentsSize;
 
+    Member<ScrollAndScaleEmulator> m_scrollAndScaleEmulator;
+
     int m_scrollbarsAvoidingResizer;
     bool m_scrollbarsSuppressed;