Adjust for pipeline stalls

Bug: 20853441

Calculating duration that crosses the UI-RT
sync point will now subtract out the time spent waiting
in queue under the assumption that this time will be
accounted for in the previous frame's metrics

Change-Id: Ia8213f4410638840613f5ae439e98dfb77532a6a
diff --git a/libs/hwui/JankTracker.cpp b/libs/hwui/JankTracker.cpp
index 5c0801e..eb9b55f 100644
--- a/libs/hwui/JankTracker.cpp
+++ b/libs/hwui/JankTracker.cpp
@@ -31,7 +31,7 @@
         "High input latency",
         "Slow UI thread",
         "Slow bitmap uploads",
-        "Slow draw",
+        "Slow issue draw commands",
 };
 
 struct Comparison {
@@ -223,7 +223,7 @@
     mData->jankFrameCount++;
 
     for (int i = 0; i < NUM_BUCKETS; i++) {
-        int64_t delta = frame[COMPARISONS[i].end] - frame[COMPARISONS[i].start];
+        int64_t delta = frame.duration(COMPARISONS[i].start, COMPARISONS[i].end);
         if (delta >= mThresholds[i] && delta < IGNORE_EXCEEDING) {
             mData->jankTypeCounts[i]++;
         }