Fixing crash in TraceHelper when dragging same message across multiple threads

Change-Id: I976a8ae5ac1786d3984b1ff069a8a0c348f48e1c
diff --git a/src/com/android/launcher3/util/TraceHelper.java b/src/com/android/launcher3/util/TraceHelper.java
index 0f3ac57..bde9c0a 100644
--- a/src/com/android/launcher3/util/TraceHelper.java
+++ b/src/com/android/launcher3/util/TraceHelper.java
@@ -55,7 +55,7 @@
     public static void partitionSection(String sectionName, String partition) {
         if (ENABLED) {
             MutableLong time = sUpTimes.get(sectionName);
-            if (time.value >= 0) {
+            if (time != null && time.value >= 0) {
 
                 if (SYSTEM_TRACE) {
                     Trace.endSection();
@@ -78,7 +78,7 @@
     public static void endSection(String sectionName, String msg) {
         if (ENABLED) {
             MutableLong time = sUpTimes.get(sectionName);
-            if (time.value >= 0) {
+            if (time != null && time.value >= 0) {
                 if (SYSTEM_TRACE) {
                     Trace.endSection();
                 }