LibVideo/PlaybackManager: Use a function to start the internal timer

In addition, this renames the internal timer to better suit its new
purpose since the playback state handlers were added. Not only is it
used to time frame presentations, but also to poll the queue when
seeking or buffering.

Userland/Libraries/LibVideo/PlaybackManager.cpp

@@ -56,7 +56,7 @@ DecoderErrorOr<NonnullOwnPtr<PlaybackManager>> PlaybackManager::create(NonnullOw
     auto frame_queue = DECODER_TRY_ALLOC(VideoFrameQueue::create());
     auto playback_manager = DECODER_TRY_ALLOC(try_make<PlaybackManager>(demuxer, track, move(decoder), move(frame_queue)));
 
-    playback_manager->m_present_timer = DECODER_TRY_ALLOC(Core::Timer::create_single_shot(0, [&self = *playback_manager] { self.timer_callback(); }));
+    playback_manager->m_state_update_timer = DECODER_TRY_ALLOC(Core::Timer::create_single_shot(0, [&self = *playback_manager] { self.timer_callback(); }));
 
     playback_manager->m_decode_thread = DECODER_TRY_ALLOC(Threading::Thread::try_create([&self = *playback_manager] {
         while (!self.m_stop_decoding.load())
@@ -176,7 +176,7 @@ void PlaybackManager::dispatch_state_change()
 
 void PlaybackManager::timer_callback()
 {
-    TRY_OR_FATAL_ERROR(m_playback_handler->on_timer_callback());
+    TRY_OR_FATAL_ERROR(m_playback_handler->do_timed_state_update());
 }
 
 void PlaybackManager::seek_to_timestamp(Time target_timestamp, SeekMode seek_mode)
@@ -204,6 +204,11 @@ Optional<FrameQueueItem> PlaybackManager::dequeue_one_frame()
     return result.release_value();
 }
 
+void PlaybackManager::set_state_update_timer(int delay_ms)
+{
+    m_state_update_timer->start(delay_ms);
+}
+
 void PlaybackManager::restart_playback()
 {
     seek_to_timestamp(Time::zero());
@@ -404,7 +409,7 @@ private:
     ErrorOr<void> on_enter() override
     {
         m_last_present_in_real_time = Time::now_monotonic();
-        return on_timer_callback();
+        return do_timed_state_update();
     }
 
     StringView name() override { return "Playing"sv; }
@@ -427,13 +432,13 @@ private:
         return manager().m_last_present_in_media_time + (Time::now_monotonic() - m_last_present_in_real_time);
     }
 
-    ErrorOr<void> on_timer_callback() override
+    ErrorOr<void> do_timed_state_update() override
     {
         auto set_presentation_timer = [&]() {
             auto frame_time_ms = (manager().m_next_frame->timestamp() - current_time()).to_milliseconds();
             VERIFY(frame_time_ms <= NumericLimits<int>::max());
             dbgln_if(PLAYBACK_MANAGER_DEBUG, "Time until next frame is {}ms", frame_time_ms);
-            manager().m_present_timer->start(max(static_cast<int>(frame_time_ms), 0));
+            manager().set_state_update_timer(max(static_cast<int>(frame_time_ms), 0));
         };
 
         if (manager().m_next_frame.has_value() && current_time() < manager().m_next_frame->timestamp()) {
@@ -547,20 +552,20 @@ class PlaybackManager::BufferingStateHandler : public PlaybackManager::ResumingS
 
     ErrorOr<void> on_enter() override
     {
-        manager().m_present_timer->start(buffering_or_seeking_decode_wait_time);
+        manager().set_state_update_timer(buffering_or_seeking_decode_wait_time);
         return {};
     }
 
     StringView name() override { return "Buffering"sv; }
 
-    ErrorOr<void> on_timer_callback() override
+    ErrorOr<void> do_timed_state_update() override
     {
         auto buffer_is_full = manager().m_buffer_is_full.load();
         dbgln_if(PLAYBACK_MANAGER_DEBUG, "Buffering timer callback has been called. Buffer is {}.", buffer_is_full ? "full, exiting"sv : "not full, waiting"sv);
         if (buffer_is_full)
             return assume_next_state();
 
-        manager().m_present_timer->start(buffering_or_seeking_decode_wait_time);
+        manager().set_state_update_timer(buffering_or_seeking_decode_wait_time);
         return {};
     }
 
@@ -644,7 +649,7 @@ private:
         }
 
         dbgln_if(PLAYBACK_MANAGER_DEBUG, "Frame queue is empty while seeking, waiting for buffer to fill.");
-        manager().m_present_timer->start(buffering_or_seeking_decode_wait_time);
+        manager().set_state_update_timer(buffering_or_seeking_decode_wait_time);
         return {};
     }
 
@@ -663,7 +668,7 @@ private:
     }
 
     // We won't need this override when threaded, the queue can pause us in on_enter().
-    ErrorOr<void> on_timer_callback() override
+    ErrorOr<void> do_timed_state_update() override
     {
         dbgln_if(PLAYBACK_MANAGER_DEBUG, "Seeking wait finished, attempting to dequeue until timestamp.");
         return skip_samples_until_timestamp();

Userland/Libraries/LibVideo/PlaybackManager.h

@@ -161,6 +161,7 @@ private:
     Optional<Time> seek_demuxer_to_most_recent_keyframe(Time timestamp, Optional<Time> earliest_available_sample = OptionalNone());
 
     Optional<FrameQueueItem> dequeue_one_frame();
+    void set_state_update_timer(int delay_ms);
 
     void decode_and_queue_one_sample();
 
@@ -179,7 +180,7 @@ private:
 
     VideoFrameQueue m_frame_queue;
 
-    RefPtr<Core::Timer> m_present_timer;
+    RefPtr<Core::Timer> m_state_update_timer;
     unsigned m_decoding_buffer_time_ms = 16;
 
     RefPtr<Threading::Thread> m_decode_thread;
@@ -216,7 +217,7 @@ private:
 
         virtual Time current_time() const;
 
-        virtual ErrorOr<void> on_timer_callback() { return {}; };
+        virtual ErrorOr<void> do_timed_state_update() { return {}; };
 
     protected:
         template<class T, class... Args>