Bug 1572235: Expose a method to remove markers leftover from previous runs of the profiler. r=gerald

Differential Revision: https://phabricator.services.mozilla.com//D41275

--HG--
extra : histedit_source : c73fed719d5e5e607ede15bbbf74ed5554083b21

tools/profiler/core/ProfilerMarker.h

@@ -133,6 +133,16 @@ class ProfilerSignalSafeLinkedList {
       abort();
     }
 
+    reset();
+  }
+
+  // Reset the list of pending signals in this list.
+  // We assume that this is called at a time when it is
+  // guaranteed that no more than a single user (the caller)
+  // is accessing the list. In particular, it is only
+  // called from within the RacyRegisteredThread::ReinitializeOnResume
+  // method.
+  void reset() {
     while (mList.peek()) {
       delete mList.popHead();
     }

tools/profiler/core/RegisteredThread.h

@@ -59,6 +59,8 @@ class RacyRegisteredThread final {
   // This is called on every profiler restart. Put things that should happen at
   // that time here.
   void ReinitializeOnResume() {
+    mPendingMarkers.reset();
+
     // This is needed to cause an initial sample to be taken from sleeping
     // threads that had been observed prior to the profiler stopping and
     // restarting. Otherwise sleeping threads would not have any samples to