Add stat collection start time

Add CLOCK_MONOTONIC to signal
when the stat collection started
to allow for tracking stats
over time

Change-Id: Iab7c52f21184eea603ddc8572b9d91a951b45a00
diff --git a/libs/hwui/JankTracker.h b/libs/hwui/JankTracker.h
index 4783001..3887e5e 100644
--- a/libs/hwui/JankTracker.h
+++ b/libs/hwui/JankTracker.h
@@ -44,10 +44,11 @@
 struct ProfileData {
     std::array<uint32_t, NUM_BUCKETS> jankTypeCounts;
     // See comments on kBucket* constants for what this holds
-    std::array<uint32_t, 57> frameCounts;
+    std::array<uint32_t, 55> frameCounts;
 
     uint32_t totalFrameCount;
     uint32_t jankFrameCount;
+    nsecs_t statStartTime;
 };
 
 // TODO: Replace DrawProfiler with this