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 10897245dab43bf655cf30e9ef7aeae6ede030ae..911048dfa0d1eb700c685daeb47d4162ab8486f9 100644
--- a/third_party/WebKit/Source/core/frame/FrameView.cpp
+++ b/third_party/WebKit/Source/core/frame/FrameView.cpp
@@ -44,6 +44,7 @@
 #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"
@@ -204,6 +205,7 @@ DEFINE_TRACE(FrameView)
     visitor->trace(m_autoSizeInfo);
     visitor->trace(m_horizontalScrollbar);
     visitor->trace(m_verticalScrollbar);
+    visitor->trace(m_scrollAndScaleEmulator);
     visitor->trace(m_children);
     visitor->trace(m_viewportScrollableArea);
     visitor->trace(m_scrollAnchor);
@@ -1603,6 +1605,12 @@ void FrameView::setScrollPosition(const DoublePoint& scrollPoint, ScrollType scr
     ScrollableArea::setScrollPosition(newScrollPosition, scrollType, scrollBehavior);
 }
 
+void FrameView::setScrollAndScaleEmulator(ScrollAndScaleEmulator* emulator)
+{
+    m_scrollAndScaleEmulator = emulator;
+    setScrollPosition(scrollPosition(), ProgrammaticScroll, ScrollBehaviorInstant);
+}
+
 void FrameView::didUpdateElasticOverscroll()
 {
     Page* page = frame().page();
@@ -3172,12 +3180,23 @@ 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).shrunkTo(maximum).expandedTo(minimum);
+
+    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)
@@ -3296,6 +3315,17 @@ IntSize FrameView::contentsSize() const
 
 IntPoint FrameView::minimumScrollPosition() const
 {
+    IntPoint minimum = calculateMinimumScrollPosition();
+    IntPoint maximum = calculateMaximumScrollPosition().expandedTo(minimum);
+
+    if (m_scrollAndScaleEmulator)
+        return m_scrollAndScaleEmulator->applyFramePositionOverride(minimum).shrunkTo(maximum).expandedTo(minimum);
+
+    return minimum;
+}
+
+IntPoint FrameView::calculateMinimumScrollPosition() const
+{
     return IntPoint(-scrollOrigin().x(), -scrollOrigin().y());
 }