Adding tracing to measure synthetic smooth scrolling correctness

content/browser/renderer_host/render_widget_host_view_base.cc

Index: content/browser/renderer_host/render_widget_host_view_base.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_base.cc b/content/browser/renderer_host/render_widget_host_view_base.cc
index 68404f8ea2b92b5d9e03649ef7e6857ef5939981..6b38a3a1e483d7924a0df8e8b571bcf326389871 100644
--- a/content/browser/renderer_host/render_widget_host_view_base.cc
+++ b/content/browser/renderer_host/render_widget_host_view_base.cc
@@ -4,6 +4,7 @@
 
 #include "content/browser/renderer_host/render_widget_host_view_base.h"
 
+#include "base/debug/trace_event.h"
 #include "base/logging.h"
 #include "content/browser/accessibility/browser_accessibility_manager.h"
 #include "content/browser/renderer_host/render_widget_host_impl.h"
@@ -460,6 +461,9 @@ class BasicMouseWheelSmoothScrollGesture
 
     pixels_scrolled_ += abs(event.deltaY);
 
+    TRACE_COUNTER_ID1("gpu", "smooth_scroll_by_pixels_scrolled", this,
+                      pixels_scrolled_);
+
     return true;
   }