Revert "Revert "Send multiple scheduler frame timelines.""

This reverts commit caaa47d60b83670206dcd3c34382719b1f247ab5.

Reason for revert: Fix the reverted CL in 2nd CL.

Bug: 198192508
Bug: 204941507
Test: See 2nd CL.

Change-Id: I15c693c2e0a82ef81a490319da11871bd74298b3
diff --git a/services/surfaceflinger/Scheduler/EventThread.h b/services/surfaceflinger/Scheduler/EventThread.h
index 9265a25..73ae5dc 100644
--- a/services/surfaceflinger/Scheduler/EventThread.h
+++ b/services/surfaceflinger/Scheduler/EventThread.h
@@ -204,6 +204,10 @@
     void onVSyncEvent(nsecs_t timestamp, nsecs_t expectedVSyncTimestamp,
                       nsecs_t deadlineTimestamp) override;
 
+    int64_t generateToken(nsecs_t timestamp, nsecs_t expectedVSyncTimestamp,
+                          nsecs_t deadlineTimestamp) const;
+    void generateFrameTimeline(DisplayEventReceiver::Event& event) const;
+
     const std::unique_ptr<VSyncSource> mVSyncSource GUARDED_BY(mMutex);
     frametimeline::TokenManager* const mTokenManager;