Adds scroll position/scale emulation to DevTools.

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

Index: third_party/WebKit/Source/core/frame/VisualViewport.cpp
diff --git a/third_party/WebKit/Source/core/frame/VisualViewport.cpp b/third_party/WebKit/Source/core/frame/VisualViewport.cpp
index 85c73df4a0db2517f8a404a18985d24c889f91ff..c3b4c98d779a3cb1b3b176d2d5c33cebd5d1b6d7 100644
--- a/third_party/WebKit/Source/core/frame/VisualViewport.cpp
+++ b/third_party/WebKit/Source/core/frame/VisualViewport.cpp
@@ -35,6 +35,7 @@
 #include "core/frame/LocalFrame.h"
 #include "core/frame/PageScaleConstraints.h"
 #include "core/frame/PageScaleConstraintsSet.h"
+#include "core/frame/ScrollAndScaleEmulator.h"
 #include "core/frame/Settings.h"
 #include "core/inspector/InspectorInstrumentation.h"
 #include "core/layout/TextAutosizer.h"
@@ -211,6 +212,12 @@ void VisualViewport::setScale(float scale)
     setScaleAndLocation(scale, m_offset);
 }
 
+void VisualViewport::setScrollAndScaleEmulator(const RefPtr<ScrollAndScaleEmulator>& emulator)
+{
+    m_scrollAndScaleEmulator = emulator;
+    setScaleAndLocation(this->scale(), this->location());
+}
+
 double VisualViewport::scrollLeft()
 {
     if (!mainFrame())
@@ -554,7 +561,15 @@ int VisualViewport::scrollSize(ScrollbarOrientation orientation) const
 
 IntPoint VisualViewport::minimumScrollPosition() const
 {
-    return IntPoint();
+    return flooredIntPoint(minimumScrollPositionDouble());
+}
+
+DoublePoint VisualViewport::minimumScrollPositionDouble() const
+{
+    if (m_scrollAndScaleEmulator)
+        return m_scrollAndScaleEmulator->applyVisualViewportPositionOverride(DoublePoint());
+
+    return DoublePoint();
 }
 
 IntPoint VisualViewport::maximumScrollPosition() const
@@ -583,6 +598,10 @@ DoublePoint VisualViewport::maximumScrollPositionDouble() const
 
     FloatSize maxPosition = frameViewSize - viewportSize;
     maxPosition.scale(1 / m_scale);
+
+    if (m_scrollAndScaleEmulator)
+        return m_scrollAndScaleEmulator->applyVisualViewportPositionOverride(DoublePoint(maxPosition));
+
     return DoublePoint(maxPosition);
 }