Implement Wheel Gesture Scrolling on OSX.

content/renderer/render_widget.cc

Index: content/renderer/render_widget.cc
diff --git a/content/renderer/render_widget.cc b/content/renderer/render_widget.cc
index fccd8dc6d3dbd6c14ba8b75fcf7b212858f788c9..cf50779a0e97674dc1de7b5928309f54067766dc 100644
--- a/content/renderer/render_widget.cc
+++ b/content/renderer/render_widget.cc
@@ -962,6 +962,27 @@ void RenderWidget::OnDidHandleKeyEvent() {
     owner_delegate_->RenderWidgetDidHandleKeyEvent();
 }
 
+void RenderWidget::ObserveGestureEventAndResult(

[Charlie Reis, 2016/03/09 22:49:17]

nit: Move above OnDidHandleKeyEvent.

[dtapuska, 2016/03/10 19:51:15]

Done.

+    const blink::WebGestureEvent& gesture_event,
+    const gfx::Vector2dF& unused_delta,
+    bool event_processed) {
+  if (!compositor_deps_->IsElasticOverscrollEnabled())
+    return;
+
+  cc::InputHandlerScrollResult scroll_result;
+  scroll_result.did_scroll = event_processed;
+  scroll_result.did_overscroll_root = !unused_delta.IsZero();
+  scroll_result.unused_scroll_delta = unused_delta;
+
+  RenderThreadImpl* render_thread = RenderThreadImpl::current();
+  InputHandlerManager* input_handler_manager =
+      render_thread ? render_thread->input_handler_manager() : NULL;
+  if (input_handler_manager) {
+    input_handler_manager->ObserveGestureEventAndResultOnMainThread(
+        routing_id_, gesture_event, scroll_result);
+  }
+}
+
 void RenderWidget::OnDidOverscroll(const DidOverscrollParams& params) {
   Send(new InputHostMsg_DidOverscroll(routing_id_, params));
 }