Adds scroll position/scale emulation to DevTools.

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

Index: third_party/WebKit/Source/core/frame/FrameView.cpp
diff --git a/third_party/WebKit/Source/core/frame/FrameView.cpp b/third_party/WebKit/Source/core/frame/FrameView.cpp
index 92177225f6e30dbaa865f5197f386664f36000e4..102d04c4af64cc09cf9deaaf9be5b5132ff9347d 100644
--- a/third_party/WebKit/Source/core/frame/FrameView.cpp
+++ b/third_party/WebKit/Source/core/frame/FrameView.cpp
@@ -43,6 +43,7 @@
 #include "core/frame/LocalFrame.h"
 #include "core/frame/Location.h"
 #include "core/frame/PageScaleConstraintsSet.h"
+#include "core/frame/ScrollAndScaleEmulator.h"
 #include "core/frame/Settings.h"
 #include "core/frame/TopControls.h"
 #include "core/frame/VisualViewport.h"
@@ -1586,6 +1587,12 @@ void FrameView::setScrollPosition(const DoublePoint& scrollPoint, ScrollType scr
     ScrollableArea::setScrollPosition(newScrollPosition, scrollType, scrollBehavior);
 }
 
+void FrameView::setScrollAndScaleEmulator(const RefPtr<ScrollAndScaleEmulator>& emulator)
+{
+    m_scrollAndScaleEmulator = emulator;
+    setScrollPosition(scrollPosition(), ProgrammaticScroll, ScrollBehaviorInstant);
+}
+
 void FrameView::didUpdateElasticOverscroll()
 {
     Page* page = frame().page();
@@ -3163,12 +3170,24 @@ void FrameView::setTopControlsViewportAdjustment(float adjustment)
 
 IntPoint FrameView::maximumScrollPosition() const
 {
+    IntPoint minimum = calculateMinimumScrollPosition();
+    IntPoint maximum = calculateMaximumScrollPosition().expandedTo(minimum);
+
+    if (m_scrollAndScaleEmulator) {
+        return m_scrollAndScaleEmulator->applyFramePositionOverride(maximum, minimum, maximum);
+    }
+
+    return maximum;
+}
+
+IntPoint FrameView::calculateMaximumScrollPosition() const
+{
     // Make the same calculation as in CC's LayerImpl::MaxScrollOffset()
     // FIXME: We probably shouldn't be storing the bounds in a float. crbug.com/422331.
     IntSize visibleSize = visibleContentSize(ExcludeScrollbars) + topControlsSize();
     IntSize contentBounds = contentsSize();
     IntPoint maximumPosition = -scrollOrigin() + (contentBounds - visibleSize);
-    return maximumPosition.expandedTo(minimumScrollPosition());
+    return maximumPosition;
 }
 
 void FrameView::addChild(Widget* child)
@@ -3287,6 +3306,17 @@ IntSize FrameView::contentsSize() const
 
 IntPoint FrameView::minimumScrollPosition() const
 {
+    if (m_scrollAndScaleEmulator) {
+        IntPoint minimum = calculateMinimumScrollPosition();
+        IntPoint maximum = calculateMaximumScrollPosition().expandedTo(minimum);
+        return m_scrollAndScaleEmulator->applyFramePositionOverride(minimum, minimum, maximum);
+    }
+
+    return calculateMinimumScrollPosition();
+}
+
+IntPoint FrameView::calculateMinimumScrollPosition() const
+{
     return IntPoint(-scrollOrigin().x(), -scrollOrigin().y());
 }