Revert "[throughput] Track last frame"

This reverts commit fd2cb104.

Reason for revert: causing crash

Original change's description:
> [throughput] Track last frame
> 
> It could happen that after a BeginImpl(Main)Frame is reported, a tracker
> is scheduled to terminate. In this case, any subsequent handling of
> that impl(main)-frame will be lost. In other words, we completely lost
> track of the last frame.
> 
> This CL fixes the impl frame, the fix for main frame comes later because
> this CL is already big.
> 
> Bug: 1055844
> Change-Id: I1cc65e9a5d973ecb67c83105be03f7bc08139dae
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2079134
> Commit-Queue: Xida Chen <xidachen@chromium.org>
> Reviewed-by: Robert Flack <flackr@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#752529}

TBR=flackr@chromium.org,xidachen@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 1055844
Change-Id: I5c96139dd4eb8bd38d2133a1b9d8d4d69bacff18
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2122041Reviewed-by: Xida Chen <xidachen@chromium.org>
Commit-Queue: Xida Chen <xidachen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#753621}

cc/metrics/frame_sequence_tracker.h

@@ -192,8 +192,6 @@ class CC_EXPORT FrameSequenceTrackerCollection {
   ActiveFrameSequenceTrackers FrameSequenceTrackerActiveTypes();
 
   FrameSequenceTracker* GetTrackerForTesting(FrameSequenceTrackerType type);
-  FrameSequenceTracker* GetRemovalTrackerForTesting(
-      FrameSequenceTrackerType type);
 
   void SetUkmManager(UkmManager* manager);
 
@@ -201,8 +199,6 @@ class CC_EXPORT FrameSequenceTrackerCollection {
   friend class FrameSequenceTrackerTest;
 
   void RecreateTrackers(const viz::BeginFrameArgs& args);
-  // Destroy the trackers that are ready to be terminated.
-  void DestroyTrackers();
 
   const bool is_single_threaded_;
   // The callsite can use the type to manipulate the tracker.
@@ -231,9 +227,9 @@ class CC_EXPORT FrameSequenceTrackerCollection {
 class CC_EXPORT FrameSequenceTracker {
  public:
   enum class TerminationStatus {
-    kActive = 0,
-    kScheduledForTermination = 1,
-    kReadyForTermination = 2,
+    kActive,
+    kScheduledForTermination,
+    kReadyForTermination,
   };
 
   static const char* GetFrameSequenceTrackerTypeName(
@@ -439,11 +435,9 @@ class CC_EXPORT FrameSequenceTracker {
     void Advance(base::TimeTicks new_timestamp);
   } trace_data_;
 
-  // True when an impl-impl is not ended. A tracker is ready for termination
-  // only when the last impl-frame is ended (ReportFrameEnd).
+#if DCHECK_IS_ON()
   bool is_inside_frame_ = false;
 
-#if DCHECK_IS_ON()
   // This stringstream represents a sequence of frame reporting activities on
   // the current tracker. Each letter can be one of the following:
   // {'B', 'N', 'b', 'n', 'S', 'P'}, where