[VSync Queue] Add tracing for event queuing time and coalesced count

ui/events/blink/event_with_callback.cc

Index: ui/events/blink/event_with_callback.cc
diff --git a/ui/events/blink/event_with_callback.cc b/ui/events/blink/event_with_callback.cc
index 90d2a57bfbdd7da83aa7d536f59cac99a87bdbc9..5808b25e69ab368a74b1fc922dff9d48de14e742 100644
--- a/ui/events/blink/event_with_callback.cc
+++ b/ui/events/blink/event_with_callback.cc
@@ -5,6 +5,7 @@
 #include "ui/events/blink/event_with_callback.h"
 
 #include "base/memory/ptr_util.h"
+#include "base/trace_event/trace_event.h"
 #include "ui/events/blink/blink_event_util.h"
 #include "ui/events/blink/did_overscroll_params.h"
 #include "ui/events/blink/web_input_event_traits.h"
@@ -23,6 +24,8 @@ EventWithCallback::EventWithCallback(
       latency_(latency),
       creation_timestamp_(timestamp_now),
       last_coalesced_timestamp_(timestamp_now) {
+  TRACE_EVENT_ASYNC_BEGIN0("input", "InputHandlerProxy::EventWithCallback",
+                           this);
   original_events_.emplace_back(std::move(event), callback);
 }
 
@@ -36,11 +39,15 @@ EventWithCallback::EventWithCallback(
       latency_(latency),
       creation_timestamp_(creation_timestamp),
       last_coalesced_timestamp_(last_coalesced_timestamp) {
+  TRACE_EVENT_ASYNC_BEGIN0("input", "InputHandlerProxy::EventWithCallback",
+                           this);
   if (original_events)
     original_events_.splice(original_events_.end(), *original_events);
 }
 
-EventWithCallback::~EventWithCallback() {}
+EventWithCallback::~EventWithCallback() {
+  TRACE_EVENT_ASYNC_END0("input", "InputHandlerProxy::EventWithCallback", this);
+}
 
 bool EventWithCallback::CanCoalesceWith(const EventWithCallback& other) const {
   return CanCoalesce(other.event(), event());