Bug 1027573 - Crash when measuring memory in about:memory while using Web Audio. r=roc

content/media/AudioNodeEngine.h

@@ -360,8 +360,10 @@ public:
                            AudioNodeSizes& aUsage) const
   {
     aUsage.mEngine = SizeOfIncludingThis(aMallocSizeOf);
-    aUsage.mDomNode = mNode->SizeOfIncludingThis(aMallocSizeOf);
-    aUsage.mNodeType = mNode->NodeType();
+    if (HasNode()) {
+      aUsage.mDomNode = mNode->SizeOfIncludingThis(aMallocSizeOf);
+      aUsage.mNodeType = mNode->NodeType();
+    }
   }
 
 private:

content/media/MediaStreamGraph.cpp

@@ -2786,7 +2786,8 @@ MediaStreamGraphImpl::CollectReports(nsIHandleReportCallback* aHandleReport,
 
   for (size_t i = 0; i < mAudioStreamSizes.Length(); i++) {
     const AudioNodeSizes& usage = mAudioStreamSizes[i];
-    const char* const nodeType =  usage.mNodeType.get();
+    const char* const nodeType =  usage.mNodeType.IsEmpty() ?
+                                  "<unknown>" : usage.mNodeType.get();
 
     nsPrintfCString domNodePath("explicit/webaudio/audio-node/%s/dom-nodes",
                                 nodeType);

content/media/MediaStreamGraph.h

@@ -232,6 +232,7 @@ public:
  */
 struct AudioNodeSizes
 {
+  AudioNodeSizes() : mDomNode(0), mStream(0), mEngine(0), mNodeType() {}
   size_t mDomNode;
   size_t mStream;
   size_t mEngine;