Bug 971094 - Part 0: Add some null checks to the profiler's usage of Observation::Filename(). r=BenWa

tools/profiler/ProfilerIOInterposeObserver.cpp

@@ -36,11 +36,15 @@ void ProfilerIOInterposeObserver::Observe(Observation& aObservation)
   }
   ProfilerBacktrace* stack = profiler_get_backtrace();
 
-  IOMarkerPayload* markerPayload = new IOMarkerPayload(
-                           aObservation.Reference(),
-                           NS_ConvertUTF16toUTF8(aObservation.Filename()).get(),
-                           aObservation.Start(),
-                           aObservation.End(),
-                           stack);
+  nsCString filename;
+  if (aObservation.Filename()) {
+    filename = NS_ConvertUTF16toUTF8(aObservation.Filename());
+  }
+
+  IOMarkerPayload* markerPayload = new IOMarkerPayload(aObservation.Reference(),
+                                                       filename.get(),
+                                                       aObservation.Start(),
+                                                       aObservation.End(),
+                                                       stack);
   PROFILER_MARKER_PAYLOAD(str, markerPayload);
 }

tools/profiler/ProfilerMarkers.cpp

@@ -115,9 +115,9 @@ IOMarkerPayload::IOMarkerPayload(const char* aSource,
                                  const mozilla::TimeStamp& aEndTime,
                                  ProfilerBacktrace* aStack)
   : ProfilerMarkerPayload(aStartTime, aEndTime, aStack),
-    mSource(aSource),
-    mFilename(strdup(aFilename))
+    mSource(aSource)
 {
+  mFilename = aFilename ? strdup(aFilename) : nullptr;
   MOZ_ASSERT(aSource);
 }