Bug 693976 - Don't parse /proc/self/maps once for every entry in /proc/self/smaps. r=khuey

xpcom/base/MapsMemoryReporter.cpp

@@ -175,6 +175,7 @@ private:
                nsISupports *aClosure,
                CategoriesSeen *aCategoriesSeen);
 
+  bool mSearchedForLibxul;
   nsCString mLibxulDir;
   nsCStringHashSet mMozillaLibraries;
 };
@@ -182,6 +183,7 @@ private:
 NS_IMPL_THREADSAFE_ISUPPORTS1(MapsReporter, nsIMemoryMultiReporter)
 
 MapsReporter::MapsReporter()
+  : mSearchedForLibxul(false)
 {
   const PRUint32 len = NS_ARRAY_LENGTH(mozillaLibraries);
   mMozillaLibraries.Init(len);
@@ -233,6 +235,11 @@ MapsReporter::CollectReports(nsIMemoryMultiReporterCallback *aCallback,
 nsresult
 MapsReporter::FindLibxul()
 {
+  if (mSearchedForLibxul)
+    return NS_OK;
+
+  mSearchedForLibxul = true;
+
   mLibxulDir.Truncate();
 
   // Note that we're scanning /proc/self/*maps*, not smaps, here.