[tracing] Hoist (over)scroll unused delta tracing

This CL removes the following arguments from
InputHandlerProxy::DidOverscroll():

  debug.dx
  debug.dy

and adds the following arguments to
InputHandlerProxy::HandleGestureScrollUpdate_Result instead:

  scroll_deltas.did_overscroll_root
  scroll_deltas.unused_delta_x
  scroll_deltas.unused_delta_y

This has two benefits:

  1. We will be able to get unused deltas from field traces.
  2. The unused delta will be logged together with other scroll
     delta-related information (so less work will be required at
     analysis time).

PERFETTO_TESTS=`autoninja -C out/Default perfetto_diff_tests && out/Default/bin/run_perfetto_diff_tests`

Bug: b:394015537
Change-Id: I4db6a11cbc8c0fe5df7a6c8573e9b3f1ee0391ae
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6225802
Commit-Queue: Petr Cermak <petrcermak@chromium.org>
Auto-Submit: Petr Cermak <petrcermak@chromium.org>
Commit-Queue: Jonathan Ross <jonross@chromium.org>
Reviewed-by: Jonathan Ross <jonross@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1416157}

base/tracing/protos/chrome_track_event.proto

@@ -1281,6 +1281,13 @@ message ScrollDeltas {
   // The array of predicted deltas of inputs which were shown together in one
   // GPU frame.
   repeated float segregated_predicted_deltas_in_gpu_frame_y = 14;
+
+  // Data for overscrolls.
+  // Whether any of the scroll delta was unused.
+  optional bool did_overscroll_root = 15;
+  // The amount of the scroll delta that was not used for scrolling.
+  optional float unused_delta_x = 16;
+  optional float unused_delta_y = 17;
 }
 
 // Debug information for system layer of audio rendering on Windows.

services/tracing/perfetto/privacy_filtered_fields-inl.h

@@ -380,8 +380,8 @@ constexpr MessageInfo kTabSwitchMeasurement = {kTabSwitchMeasurementIndices,
                                                nullptr};
 
 // Proto Message: ScrollDeltas
-constexpr int kScrollDeltasIndices[] = {1, 2,  3,  4,  5,  6,  7, 8,
-                                        9, 10, 11, 12, 13, 14, -1};
+constexpr int kScrollDeltasIndices[] = {1,  2,  3,  4,  5,  6,  7,  8,  9,
+                                        10, 11, 12, 13, 14, 15, 16, 17, -1};
 constexpr MessageInfo kScrollDeltas = {kScrollDeltasIndices, nullptr};
 
 // Proto Message: WinRenderAudioFromSource

third_party/blink/renderer/platform/widget/input/input_handler_proxy.cc

@@ -1202,17 +1202,19 @@ InputHandlerProxy::HandleGestureScrollUpdate(
   TRACE_EVENT(
       "input,input.scrolling",
       "InputHandlerProxy::HandleGestureScrollUpdate_Result",
-      [trace_id, provided_delta_x, provided_delta_y,
-       visual_offset_x = scroll_result.current_visual_offset.x(),
-       visual_offset_y = scroll_result.current_visual_offset.y()](
-          perfetto::EventContext& ctx) {
+      [&](perfetto::EventContext& ctx) {
         auto* event = ctx.event<perfetto::protos::pbzero::ChromeTrackEvent>();
         auto* scroll_data = event->set_scroll_deltas();
         scroll_data->set_trace_id(trace_id);
         scroll_data->set_provided_to_compositor_delta_x(provided_delta_x);
         scroll_data->set_provided_to_compositor_delta_y(provided_delta_y);
-        scroll_data->set_visual_offset_x(visual_offset_x);
-        scroll_data->set_visual_offset_y(visual_offset_y);
+        scroll_data->set_visual_offset_x(
+            scroll_result.current_visual_offset.x());
+        scroll_data->set_visual_offset_y(
+            scroll_result.current_visual_offset.y());
+        scroll_data->set_did_overscroll_root(scroll_result.did_overscroll_root);
+        scroll_data->set_unused_delta_x(scroll_result.unused_scroll_delta.x());
+        scroll_data->set_unused_delta_y(scroll_result.unused_scroll_delta.y());
       });
 
   HandleOverscroll(gesture_event.PositionInWidget(), scroll_result);
@@ -1715,9 +1717,7 @@ void InputHandlerProxy::HandleOverscroll(
   if (!scroll_result.did_overscroll_root)
     return;
 
-  TRACE_EVENT2("input", "InputHandlerProxy::DidOverscroll", "dx",
-               scroll_result.unused_scroll_delta.x(), "dy",
-               scroll_result.unused_scroll_delta.y());
+  TRACE_EVENT("input", "InputHandlerProxy::DidOverscroll");
 
   // Bundle overscroll message with triggering event response, saving an IPC.
   current_overscroll_params_ = std::make_unique<DidOverscrollParams>();