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 d157ed658006f891bb10444218542c4402869ac1..5c990cc2ba11a5e67854fd34b213ec446148a962 100644
--- a/content/renderer/gpu/render_widget_compositor_delegate.h
+++ b/content/renderer/gpu/render_widget_compositor_delegate.h
@@ -36,6 +36,12 @@ class CONTENT_EXPORT RenderWidgetCompositorDelegate {
       float page_scale,
       float top_controls_delta) = 0;
 
+  // Record use count of wheel/touch sources for scrolling on the compositor
+  // tread.
+  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;