gpu benchmarking swipe for touchpad

content/renderer/gpu/gpu_benchmarking_extension.h

Index: content/renderer/gpu/gpu_benchmarking_extension.h
diff --git a/content/renderer/gpu/gpu_benchmarking_extension.h b/content/renderer/gpu/gpu_benchmarking_extension.h
index 2b69d2b1329b1bb60d2669771ee08bf5498d25a4..8dce8d08445cd8512f767dbea67bd2855a6b1e54 100644
--- a/content/renderer/gpu/gpu_benchmarking_extension.h
+++ b/content/renderer/gpu/gpu_benchmarking_extension.h
@@ -48,7 +48,13 @@ class GpuBenchmarking : public gin::Wrappable<GpuBenchmarking> {
   bool GestureSourceTypeSupported(int gesture_source_type);
   bool SmoothScrollBy(gin::Arguments* args);
   bool SmoothDrag(gin::Arguments* args);
+
+  // This function generates a scroll followed by a fling. The default input
+  // source is touch; Source, velocity_x, and velocity_y are extra args that
+  // are necessary for a touchpad fling. Note that swipe only works when
+  // threaded compositing is enabled.

[bokan, 2017/03/10 14:41:57]

Is this because of a difference in how main thread flings are handled?

[sahel, 2017/03/10 21:51:41]

I tried to debug it to see what the cause is. It seems like when a GFS is
handled by main thread, the call back function of swipe is never called.

One can still use swipe for fling on main thread, but there shouldn't be
any dependency to the call back function e.g. if you check scrollTop
in the callback function recursively and decide to finish the test based
on its value, the test will timeout because the callback function is never
called.

I changed the comment to make it more precise. 

[bokan, 2017/03/13 13:43:13]

Acknowledged.

   bool Swipe(gin::Arguments* args);
+
   bool ScrollBounce(gin::Arguments* args);
   bool PinchBy(gin::Arguments* args);
   bool Tap(gin::Arguments* args);