UMA metrics for use count of wheel and touch scrolls.

content/renderer/gpu/render_widget_compositor_delegate.h

Index: content/renderer/gpu/render_widget_compositor_delegate.h
diff --git a/content/renderer/gpu/render_widget_compositor_delegate.h b/content/renderer/gpu/render_widget_compositor_delegate.h
index 405a49dc438ee4d13394c43479ff526115a9db08..a9e7392875d4f613c0ade4a8cfca9a604033d3bb 100644
--- a/content/renderer/gpu/render_widget_compositor_delegate.h
+++ b/content/renderer/gpu/render_widget_compositor_delegate.h
@@ -39,6 +39,12 @@ class CONTENT_EXPORT RenderWidgetCompositorDelegate {
       float page_scale,
       float top_controls_delta) = 0;
 
+  // Record use count of wheel/touch sources for scrolling on the compositor
+  // thread.
+  virtual void RecordWheelAndTouchScrollingCount(
+      bool has_scrolled_by_wheel,
+      bool has_scrolled_by_touch) = 0;
+
   // Notifies that the compositor has issed a BeginMainFrame.
   virtual void BeginMainFrame(double frame_time_sec) = 0;