Exclude BufferStuffing from TimeStats atoms

Since BufferStuffing is not really a jank, including this in the jank
reasons makes it hard to find genuine number of janky frames due to
server side shortcomings.

Bug: 185595205
Test: libsurfaceflinger_unittest
Change-Id: I5e355f883c374a27b0e44453cfb857f059eb23d0
diff --git a/services/surfaceflinger/TimeStats/TimeStats.cpp b/services/surfaceflinger/TimeStats/TimeStats.cpp
index 16c6bb3..3d82afa 100644
--- a/services/surfaceflinger/TimeStats/TimeStats.cpp
+++ b/services/surfaceflinger/TimeStats/TimeStats.cpp
@@ -745,7 +745,7 @@
 static const constexpr int32_t kValidJankyReason = JankType::DisplayHAL |
         JankType::SurfaceFlingerCpuDeadlineMissed | JankType::SurfaceFlingerGpuDeadlineMissed |
         JankType::AppDeadlineMissed | JankType::PredictionError |
-        JankType::SurfaceFlingerScheduling | JankType::BufferStuffing;
+        JankType::SurfaceFlingerScheduling;
 
 template <class T>
 static void updateJankPayload(T& t, int32_t reasons) {
@@ -771,9 +771,11 @@
         if ((reasons & JankType::SurfaceFlingerScheduling) != 0) {
             t.jankPayload.totalSFScheduling++;
         }
-        if ((reasons & JankType::BufferStuffing) != 0) {
-            t.jankPayload.totalAppBufferStuffing++;
-        }
+    }
+
+    // We want to track BufferStuffing separately as it can provide info on latency issues
+    if (reasons & JankType::BufferStuffing) {
+        t.jankPayload.totalAppBufferStuffing++;
     }
 }