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 d61236e70169dcb61a51dc89a9ade87c94667a65..4e8a1b3246ac01195692ab1205828935b06ac124 100644
--- a/third_party/WebKit/Source/core/frame/VisualViewport.cpp
+++ b/third_party/WebKit/Source/core/frame/VisualViewport.cpp
@@ -36,6 +36,7 @@
 #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"
@@ -77,6 +78,7 @@ VisualViewport::~VisualViewport()
 DEFINE_TRACE(VisualViewport)
 {
     visitor->trace(m_frameHost);
+    visitor->trace(m_scrollAndScaleEmulator);
     ScrollableArea::trace(visitor);
 }
 
@@ -213,6 +215,12 @@ void VisualViewport::setScale(float scale)
     setScaleAndLocation(scale, m_offset);
 }
 
+void VisualViewport::setScrollAndScaleEmulator(ScrollAndScaleEmulator* emulator)
+{
+    m_scrollAndScaleEmulator = emulator;
+    clampToBoundaries();
+}
+
 double VisualViewport::scrollLeft()
 {
     if (!mainFrame())
@@ -549,7 +557,24 @@ int VisualViewport::scrollSize(ScrollbarOrientation orientation) const
 
 IntPoint VisualViewport::minimumScrollPosition() const
 {
-    return IntPoint();
+    return flooredIntPoint(minimumScrollPositionDouble());
+}
+
+DoublePoint VisualViewport::minimumScrollPositionDouble() const
+{
+    DoublePoint minimum = calculateMinimumScrollPositionDouble();
+
+    if (m_scrollAndScaleEmulator) {
+        DoublePoint maximum = calculateMaximumScrollPositionDouble();
+        return m_scrollAndScaleEmulator->applyVisualViewportPositionOverride(minimum).shrunkTo(maximum).expandedTo(minimum);
+    }
+
+    return minimum;
+}
+
+DoublePoint VisualViewport::calculateMinimumScrollPositionDouble() const
+{
+    return DoublePoint();
 }
 
 IntPoint VisualViewport::maximumScrollPosition() const
@@ -559,6 +584,18 @@ IntPoint VisualViewport::maximumScrollPosition() const
 
 DoublePoint VisualViewport::maximumScrollPositionDouble() const
 {
+    DoublePoint maximum = calculateMaximumScrollPositionDouble();
+
+    if (m_scrollAndScaleEmulator) {
+        DoublePoint minimum = calculateMinimumScrollPositionDouble();
+        return m_scrollAndScaleEmulator->applyVisualViewportPositionOverride(maximum).shrunkTo(maximum).expandedTo(minimum);
+    }
+
+    return maximum;
+}
+
+DoublePoint VisualViewport::calculateMaximumScrollPositionDouble() const
+{
     if (!mainFrame())
         return IntPoint();