--- a/docshell/base/nsDocShell.cpp
+++ b/docshell/base/nsDocShell.cpp
@@ -2853,31 +2853,24 @@ nsDocShell::PopProfileTimelineMarkers(JS
   // {name,start,end} JS object.
   // Paint markers are different because paint is handled at root docShell level
   // in the information that a paint was done is then stored at each sub
   // docShell level but we can only be sure that a paint did happen in a
   // docShell if an Layer marker type was recorded too.
 
   nsTArray<mozilla::dom::ProfileTimelineMarker> profileTimelineMarkers;
 
-  // If we see an unpaired START, we keep it around for the next call
-  // to PopProfileTimelineMarkers.  We store the kept START objects in
-  // this array.
-  decltype(mProfileTimelineMarkers) keptMarkers;
-
   for (uint32_t i = 0; i < mProfileTimelineMarkers.Length(); ++i) {
     ProfilerMarkerTracing* startPayload = static_cast<ProfilerMarkerTracing*>(
       mProfileTimelineMarkers[i]->mPayload);
     const char* startMarkerName = mProfileTimelineMarkers[i]->mName;
 
     bool hasSeenPaintedLayer = false;
 
     if (startPayload->GetMetaData() == TRACING_INTERVAL_START) {
-      bool hasSeenEnd = false;
-
       // The assumption is that the devtools timeline flushes markers frequently
       // enough for the amount of markers to always be small enough that the
       // nested for loop isn't going to be a performance problem.
       for (uint32_t j = i + 1; j < mProfileTimelineMarkers.Length(); ++j) {
         ProfilerMarkerTracing* endPayload = static_cast<ProfilerMarkerTracing*>(
           mProfileTimelineMarkers[j]->mPayload);
         const char* endMarkerName = mProfileTimelineMarkers[j]->mName;
 
@@ -2895,36 +2888,25 @@ nsDocShell::PopProfileTimelineMarkers(JS
           if (!isPaint || (isPaint && hasSeenPaintedLayer)) {
             mozilla::dom::ProfileTimelineMarker marker;
             marker.mName = NS_ConvertUTF8toUTF16(startMarkerName);
             marker.mStart = mProfileTimelineMarkers[i]->mTime;
             marker.mEnd = mProfileTimelineMarkers[j]->mTime;
             profileTimelineMarkers.AppendElement(marker);
           }
 
-          // We want the start to be dropped either way.
-          hasSeenEnd = true;
-
           break;
         }
       }
-
-      // If we did not see the corresponding END, keep the START.
-      if (!hasSeenEnd) {
-        keptMarkers.AppendElement(mProfileTimelineMarkers[i]);
-        mProfileTimelineMarkers.RemoveElementAt(i);
-        --i;
-      }
     }
   }
 
   ToJSValue(aCx, profileTimelineMarkers, aProfileTimelineMarkers);
 
   ClearProfileTimelineMarkers();
-  mProfileTimelineMarkers.SwapElements(keptMarkers);
 
   return NS_OK;
 #else
   return NS_ERROR_FAILURE;
 #endif
 }
 
 float
@@ -2965,17 +2947,18 @@ nsDocShell::AddProfileTimelineMarker(con
 #endif
 }
 
 void
 nsDocShell::ClearProfileTimelineMarkers()
 {
 #ifdef MOZ_ENABLE_PROFILER_SPS
   for (uint32_t i = 0; i < mProfileTimelineMarkers.Length(); ++i) {
-    delete mProfileTimelineMarkers[i];
+    delete mProfileTimelineMarkers[i]->mPayload;
+    mProfileTimelineMarkers[i]->mPayload = nullptr;
   }
   mProfileTimelineMarkers.Clear();
 #endif
 }
 
 nsIDOMStorageManager*
 nsDocShell::TopSessionStorageManager()
 {

--- a/docshell/base/nsDocShell.h
+++ b/docshell/base/nsDocShell.h
@@ -954,27 +954,21 @@ private:
     {
       InternalProfileTimelineMarker(const char* aName,
                                     ProfilerMarkerTracing* aPayload,
                                     float aTime)
         : mName(aName)
         , mPayload(aPayload)
         , mTime(aTime)
       {}
-
-      ~InternalProfileTimelineMarker()
-      {
-        delete mPayload;
-      }
-
       const char* mName;
       ProfilerMarkerTracing* mPayload;
       float mTime;
     };
-    nsTArray<InternalProfileTimelineMarker*> mProfileTimelineMarkers;
+    nsTArray<nsAutoPtr<InternalProfileTimelineMarker>> mProfileTimelineMarkers;
 
     // Get the elapsed time (in millis) since the profile timeline recording
     // started
     float GetProfileTimelineDelta();
 
     // Get rid of all the timeline markers accumulated so far
     void ClearProfileTimelineMarkers();