Adds scroll position/scale emulation to DevTools.

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

Index: third_party/WebKit/Source/core/frame/VisualViewport.h
diff --git a/third_party/WebKit/Source/core/frame/VisualViewport.h b/third_party/WebKit/Source/core/frame/VisualViewport.h
index 295c52a5ef9f2c88d69bd495aa220c02a8b0a980..e0bd6a0babd2bc7f5becadce5fcdb82a47ee40aa 100644
--- a/third_party/WebKit/Source/core/frame/VisualViewport.h
+++ b/third_party/WebKit/Source/core/frame/VisualViewport.h
@@ -55,6 +55,7 @@ class GraphicsLayer;
 class IntRect;
 class IntSize;
 class LocalFrame;
+class ScrollAndScaleEmulator;
 
 // Represents the visual viewport the user is currently seeing the page through. This
 // class corresponds to the InnerViewport on the compositor. It is a ScrollableArea; it's
@@ -100,6 +101,9 @@ public:
     void move(const FloatSize&);
     FloatPoint location() const { return m_offset; }
 
+    // Override the scroll location and scale with values from the emulator. Passing |nullptr| clears override.
+    void setScrollAndScaleEmulator(const RefPtr<ScrollAndScaleEmulator>&);
+
     // Sets the size of the inner viewport when unscaled in CSS pixels.
     void setSize(const IntSize&);
     IntSize size() const { return m_size; }
@@ -181,6 +185,7 @@ public:
     IntPoint scrollPosition() const override { return flooredIntPoint(m_offset); }
     DoublePoint scrollPositionDouble() const override { return m_offset; }
     IntPoint minimumScrollPosition() const override;
+    DoublePoint minimumScrollPositionDouble() const override;
     IntPoint maximumScrollPosition() const override;
     DoublePoint maximumScrollPositionDouble() const override;
     int visibleHeight() const override { return visibleRect().height(); }
@@ -235,6 +240,10 @@ private:
     void setupScrollbar(WebScrollbar::Orientation);
     FloatPoint clampOffsetToBoundaries(const FloatPoint&);
 
+    // Calculate the physical minimum/maximum scroll positions without any overrides applied.
+    DoublePoint calculateMinimumScrollPositionDouble() const;
+    DoublePoint calculateMaximumScrollPositionDouble() const;
+
     LocalFrame* mainFrame() const;
 
     FrameHost& frameHost() const
@@ -261,6 +270,8 @@ private:
     float m_topControlsAdjustment;
     float m_maxPageScale;
     bool m_trackPinchZoomStatsForPage;
+
+    RefPtr<ScrollAndScaleEmulator> m_scrollAndScaleEmulator;
 };
 
 } // namespace blink