Revert "Running FrameBuffer on task queue."

This reverts commit 13943b7b7f6d00568912b9969db2c7871d18e21f.

Reason for revert: Breaks chromium import bots:
https://ci.chromium.org/p/chromium/builders/webrtc.fyi/WebRTC%20Chromium%20FYI%20Android%20Tests%20%28dbg%29%20%28K%20Nexus5%29

First failure:
https://ci.chromium.org/p/chromium/builders/webrtc.fyi/WebRTC%20Chromium%20FYI%20Android%20Tests%20%28dbg%29%20%28K%20Nexus5%29/2794

Original change's description:
> Running FrameBuffer on task queue.
> 
> This prepares for running WebRTC in simulated time where event::Wait
> based timing doesn't work.
> 
> Bug: webrtc:10365
> Change-Id: Ia0f9b1cc8e3c8c27a38e45b40487050a4699d8cf
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/129962
> Reviewed-by: Philip Eliasson <philipel@webrtc.org>
> Reviewed-by: Erik Språng <sprang@webrtc.org>
> Commit-Queue: Sebastian Jansson <srte@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#27422}

TBR=sprang@webrtc.org,philipel@webrtc.org,srte@webrtc.org

Change-Id: I198a91ec1707cc8752a7fe55caf0f172e1b8e60a
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: webrtc:10365
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/131120
Reviewed-by: Henrik Boström <hbos@webrtc.org>
Commit-Queue: Henrik Boström <hbos@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#27436}
diff --git a/modules/video_coding/frame_buffer2.h b/modules/video_coding/frame_buffer2.h
index 7772167..fda496e 100644
--- a/modules/video_coding/frame_buffer2.h
+++ b/modules/video_coding/frame_buffer2.h
@@ -27,8 +27,6 @@
 #include "rtc_base/event.h"
 #include "rtc_base/experiments/rtt_mult_experiment.h"
 #include "rtc_base/numerics/sequence_number_util.h"
-#include "rtc_base/task_queue.h"
-#include "rtc_base/task_utils/repeating_task.h"
 #include "rtc_base/thread_annotations.h"
 
 namespace webrtc {
@@ -47,13 +45,7 @@
   FrameBuffer(Clock* clock,
               VCMJitterEstimator* jitter_estimator,
               VCMTiming* timing,
-              VCMReceiveStatisticsCallback* stats_callback);
-
-  FrameBuffer(Clock* clock,
-              TaskQueueFactory* task_queue_factory,
-              VCMJitterEstimator* jitter_estimator,
-              VCMTiming* timing,
-              VCMReceiveStatisticsCallback* stats_callback);
+              VCMReceiveStatisticsCallback* stats_proxy);
 
   virtual ~FrameBuffer();
 
@@ -62,9 +54,6 @@
   // TODO(philipel): Return a VideoLayerFrameId and not only the picture id.
   int64_t InsertFrame(std::unique_ptr<EncodedFrame> frame);
 
-  void InsertFrame(std::unique_ptr<EncodedFrame> frame,
-                   std::function<void(int64_t)> picture_id_handler);
-
   // Get the next frame for decoding. Will return at latest after
   // |max_wait_time_ms|.
   //  - If a frame is available within |max_wait_time_ms| it will return
@@ -75,10 +64,6 @@
   ReturnReason NextFrame(int64_t max_wait_time_ms,
                          std::unique_ptr<EncodedFrame>* frame_out,
                          bool keyframe_required = false);
-  void NextFrame(
-      int64_t max_wait_time_ms,
-      bool keyframe_required,
-      std::function<void(std::unique_ptr<EncodedFrame>, ReturnReason)> handler);
 
   // Tells the FrameBuffer which protection mode that is in use. Affects
   // the frame timing.
@@ -130,16 +115,9 @@
 
   using FrameMap = std::map<VideoLayerFrameId, FrameInfo>;
 
-  void SafePost(std::function<void()> func);
-
   // Check that the references of |frame| are valid.
   bool ValidReferences(const EncodedFrame& frame) const;
 
-  void NextFrameOnQueue() RTC_EXCLUSIVE_LOCKS_REQUIRED(crit_);
-  int64_t UpdateFramesToDecode(int64_t now_ms)
-      RTC_EXCLUSIVE_LOCKS_REQUIRED(crit_);
-  EncodedFrame* GetFrameToDecode() RTC_EXCLUSIVE_LOCKS_REQUIRED(crit_);
-
   // Update all directly dependent and indirectly dependent frames and mark
   // them as continuous if all their references has been fulfilled.
   void PropagateContinuity(FrameMap::iterator start)
@@ -180,19 +158,9 @@
   FrameMap frames_ RTC_GUARDED_BY(crit_);
   DecodedFramesHistory decoded_frames_history_ RTC_GUARDED_BY(crit_);
 
-  // TODO(srte): Remove this lock when always running on task queue.
   rtc::CriticalSection crit_;
   Clock* const clock_;
-  const bool use_task_queue_;
-
-  RepeatingTaskHandle callback_task_ RTC_GUARDED_BY(crit_);
-  std::function<void(std::unique_ptr<EncodedFrame>, ReturnReason)>
-      frame_handler_ RTC_GUARDED_BY(crit_);
-  int64_t latest_return_time_ms_ RTC_GUARDED_BY(crit_);
-  bool keyframe_required_ RTC_GUARDED_BY(crit_);
-
   rtc::Event new_continuous_frame_event_;
-
   VCMJitterEstimator* const jitter_estimator_ RTC_GUARDED_BY(crit_);
   VCMTiming* const timing_ RTC_GUARDED_BY(crit_);
   VCMInterFrameDelay inter_frame_delay_ RTC_GUARDED_BY(crit_);
@@ -206,8 +174,6 @@
 
   const bool add_rtt_to_playout_delay_;
 
-  // Defined last so it is destroyed before other members.
-  rtc::TaskQueue task_queue_;
   RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(FrameBuffer);
 };