Revert "[fuchsia] change kMaxFramesInFlight to 3 (flutter#16425)"

This reverts commit 6ff3ecc.

Author: NoamDev

shell/platform/fuchsia/flutter/session_connection.h

@@ -94,7 +94,7 @@ class SessionConnection final {
   // The maximum number of frames Flutter sent to Scenic that it can have
   // outstanding at any time. This is equivalent to how many times it has
   // called Present2() before receiving an OnFramePresented() event.
-  static constexpr int kMaxFramesInFlight = 3;
+  static constexpr int kMaxFramesInFlight = 2;
   int frames_in_flight_ = 0;
 
   int frames_in_flight_allowed_ = 0;

shell/platform/fuchsia/flutter/vsync_waiter.cc

@@ -131,15 +131,6 @@ void VsyncWaiter::AwaitVSync() {
       VsyncRecorder::GetInstance().GetLastPresentationTime();
   fml::TimePoint next_vsync = SnapToNextPhase(now, last_presentation_time,
                                               vsync_info.presentation_interval);
-
-  auto next_vsync_start_time = next_vsync - vsync_offset;
-
-  if (now >= next_vsync_start_time)
-    next_vsync_start_time =
-        next_vsync_start_time + vsync_info.presentation_interval;
-
-  fml::TimeDelta delta = next_vsync_start_time - now;
-
   task_runners_.GetUITaskRunner()->PostDelayedTask(
       [& weak_factory_ui = this->weak_factory_ui_] {
         if (!weak_factory_ui) {
@@ -152,7 +143,7 @@ void VsyncWaiter::AwaitVSync() {
           self->FireCallbackWhenSessionAvailable();
         }
       },
-      delta);
+      next_vsync - now);
 }
 
 void VsyncWaiter::FireCallbackWhenSessionAvailable() {

shell/platform/fuchsia/flutter/vsync_waiter.h

@@ -34,9 +34,6 @@ class VsyncWaiter final : public flutter::VsyncWaiter {
   async::Wait session_wait_;
   fml::WeakPtrFactory<VsyncWaiter> weak_factory_;
 
-  static constexpr fml::TimeDelta vsync_offset =
-      fml::TimeDelta::FromNanoseconds(0);
-
   // For accessing the VsyncWaiter via the UI thread, necessary for the callback
   // for AwaitVSync()
   std::unique_ptr<fml::WeakPtrFactory<VsyncWaiter>> weak_factory_ui_;