[not for review - epic CL] Adding Elastic+Momentum+Layered scrolling to views::ScrollView

ui/views/controls/scroll_view.cc

Index: ui/views/controls/scroll_view.cc
diff --git a/ui/views/controls/scroll_view.cc b/ui/views/controls/scroll_view.cc
index 68ee68fee3eaa8561e097be266a8ec202f448155..fdabd1026e2b46d322c3639bdceb95d0da4afe6a 100644
--- a/ui/views/controls/scroll_view.cc
+++ b/ui/views/controls/scroll_view.cc
@@ -7,6 +7,7 @@
 #include "base/feature_list.h"
 #include "base/logging.h"
 #include "base/macros.h"
+#include "ui/compositor/overscroll/ui_scroll_input_manager.h"
 #include "ui/events/event.h"
 #include "ui/gfx/canvas.h"
 #include "ui/native_theme/native_theme.h"
@@ -461,9 +462,13 @@ void ScrollView::OnMouseExited(const ui::MouseEvent& event) {
 
 void ScrollView::OnScrollEvent(ui::ScrollEvent* event) {
 #if defined(OS_MACOSX)
-  // TODO(tapted): Send |event| to a cc::InputHandler. For now, there's nothing
-  // to do because Widget::OnScrollEvent() will automatically process an
-  // unhandled ScrollEvent as a MouseWheelEvent.
+  ui::UIScrollInputManager* compositor_scroller =
+      GetWidget()->GetCompositor()->scroll_input_manager();
+  DCHECK(compositor_scroller);
+  if (compositor_scroller->OnScrollEvent(*event)) {
+    event->SetHandled();
+    event->StopPropagation();
+  }
 #endif
 }
 
@@ -538,6 +543,19 @@ int ScrollView::GetScrollIncrement(ScrollBar* source, bool is_page,
                          contents_viewport_->height() / 5;
 }
 
+void ScrollView::OnScrollEventFromScrollBar(ui::ScrollEvent* event) {
+  // If the scroll event is passed to the cc::InputHandler as-is, then it will
+  // hit a scroll bar Layer. Layer scrolling supports that, but only if the
+  // scroll bar track and thumb Layers implement cc::ScrollbarLayerInterface.
+  // Creating one of those requires a cc::ScrollBar instance which is more than
+  // views:: really needs to care about. For now, cheat a little and pretend
+  // events are coming from the point (0, 0) on the viewport.
+  gfx::Point location;
+  ConvertPointToWidget(contents_viewport_, &location);
+  event->set_location(location);
+  OnScrollEvent(event);
+}
+
 void ScrollView::SetHeaderOrContents(View* parent,
                                      View* new_view,
                                      View** member) {