Scroll Customization Prototype (Not for review, WIP)

Source/core/frame/LocalFrame.cpp

Index: Source/core/frame/LocalFrame.cpp
diff --git a/Source/core/frame/LocalFrame.cpp b/Source/core/frame/LocalFrame.cpp
index 3178d84acd3e95b710339411de20d438d4f5d8d7..c06d8512394632a78368e2f8d13e7e98656e3477 100644
--- a/Source/core/frame/LocalFrame.cpp
+++ b/Source/core/frame/LocalFrame.cpp
@@ -765,6 +765,33 @@ void LocalFrame::removeSpellingMarkersUnderWords(const Vector<String>& words)
     spellChecker().removeSpellingMarkersUnderWords(words);
 }
 
+static bool scrollAreaOnBothAxes(const FloatSize& delta, ScrollableArea& view)
+{
+    bool scrolledHorizontal = view.scroll(ScrollLeft, ScrollByPrecisePixel, delta.width());
+    bool scrolledVertical = view.scroll(ScrollUp, ScrollByPrecisePixel, delta.height());
+    return scrolledHorizontal || scrolledVertical;
+}
+
+// Returns true if a scroll occurred.
+bool LocalFrame::scrollByDelta(const FloatSize& delta)
+{
+    // FIXME: handle top controls.
+    if (!view())
+        return false;
+
+    if (scrollAreaOnBothAxes(delta, *view()))
+        return true;
+
+    // If this is the main frame and it didn't scroll, propagate up to the pinch viewport.
+    if (!settings()->pinchVirtualViewportEnabled() || !isMainFrame())
+        return false;
+
+    if (scrollAreaOnBothAxes(delta, page()->frameHost().pinchViewport()))
+        return true;
+
+    return false;
+}
+
 #if ENABLE(OILPAN)
 void LocalFrame::registerPluginElement(HTMLPlugInElement* plugin)
 {