Add tests for FrameBuffer3 and SyncDecoding in PC Integration Tests

Change-Id: I04ae6a694599a535347c29706e5ad40cba58155b
Bug: webrtc:13672
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/251721
Reviewed-by: Stefan Holmer <stefan@webrtc.org>
Commit-Queue: Evan Shrubsole <eshr@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#36104}

pc/test/integration_test_helpers.cc

@@ -56,4 +56,46 @@ int FindFirstMediaStatsIndexByKind(
   return -1;
 }
 
+TaskQueueMetronome::TaskQueueMetronome(TaskQueueFactory* factory,
+                                       TimeDelta tick_period)
+    : tick_period_(tick_period),
+      queue_(factory->CreateTaskQueue("MetronomeQueue",
+                                      TaskQueueFactory::Priority::HIGH)) {
+  tick_task_ = RepeatingTaskHandle::Start(queue_.Get(), [this] {
+    MutexLock lock(&mutex_);
+    for (auto* listener : listeners_) {
+      listener->OnTickTaskQueue()->PostTask(
+          ToQueuedTask([listener] { listener->OnTick(); }));
+    }
+    return tick_period_;
+  });
+}
+
+TaskQueueMetronome::~TaskQueueMetronome() {
+  RTC_DCHECK(listeners_.empty());
+  rtc::Event stop_event;
+  queue_.PostTask([this, &stop_event] {
+    tick_task_.Stop();
+    stop_event.Set();
+  });
+  stop_event.Wait(1000);
+}
+
+void TaskQueueMetronome::AddListener(TickListener* listener) {
+  MutexLock lock(&mutex_);
+  auto [it, inserted] = listeners_.insert(listener);
+  RTC_DCHECK(inserted);
+}
+
+void TaskQueueMetronome::RemoveListener(TickListener* listener) {
+  MutexLock lock(&mutex_);
+  auto it = listeners_.find(listener);
+  RTC_DCHECK(it != listeners_.end());
+  listeners_.erase(it);
+}
+
+TimeDelta TaskQueueMetronome::TickPeriod() const {
+  return tick_period_;
+}
+
 }  // namespace webrtc