Setting Accurate ScrollResult from Blink for Elastic Scroll.

content/renderer/render_view_impl.cc

Index: content/renderer/render_view_impl.cc
diff --git a/content/renderer/render_view_impl.cc b/content/renderer/render_view_impl.cc
index bb881cbbd0bdf2581d61e758bd9e8c9974b8a082..93a8cc724e4a9f6b567061c91c2334b164f8c4f5 100644
--- a/content/renderer/render_view_impl.cc
+++ b/content/renderer/render_view_impl.cc
@@ -1134,6 +1134,13 @@ void RenderView::ApplyWebPreferences(const WebPreferences& prefs,
   settings->setShowContextMenuOnMouseUp(prefs.context_menu_on_mouse_up);
 
 #if defined(OS_MACOSX)
+#if !defined(OS_IOS)
+  bool is_elastic_overscroll_enabled =
+      RenderViewImpl::FromWebView(web_view)
+          ? RenderViewImpl::FromWebView(web_view)->IsElasticOverscrollEnabled()

[piman, 2015/06/30 21:30:00]

RenderViewImpl will disappear in the future (out-of-process iframes).
It sounds like all you need here is the compositor_deps_. Can you pass those
explicitly? The callers (where web_view is for a RenderViewImpl) have one -
either RenderViewImpl::OnUpdateWebPreferences or RenderViewImpl::Initialize.

For example you can add a CompositorDependencies* parameter to this function,
maybe renaming it ApplyWebPreferencesInternal, and adding a ApplyWebPreferences
that just calls this with a NULL CompositorDependencies for the other callers.

That way, you even avoid the map lookup, and no need for
IsElasticOverscrollEnabled on the RenderWidget.

[MuVen, 2015/07/01 13:23:21]

Done. PTAL.

+          : false;
+  settings->setReportWheelOverscroll(is_elastic_overscroll_enabled);
+#endif
   settings->setDoubleTapToZoomEnabled(true);
   web_view->setMaximumLegibleScale(prefs.default_maximum_page_scale_factor);
 #endif