Bug 611405 part 2 - Avoid crash in nsMemoryReporterManager when jemalloc_stats is not available at runtime. r=bsmedberg,a=clegnitto

xpcom/base/nsMemoryReporterManager.cpp

@@ -59,10 +59,6 @@
 // with it.  So if we tried to use jemalloc_stats directly here, it
 // wouldn't be defined.  Instead, we don't include the jemalloc header
 // and weakly link against jemalloc_stats.
-//
-// NB: we don't null-check this symbol at runtime because we expect it
-// to have been resolved.  If it hasn't, the crash jumping to NULL
-// will indicate the bug.
 extern "C" {
 extern void jemalloc_stats(jemalloc_stats_t* stats)
   NS_VISIBILITY_DEFAULT __attribute__((weak));
@@ -219,6 +215,10 @@ NS_IMPL_ISUPPORTS1(nsMemoryReporterManager, nsIMemoryReporterManager)
 NS_IMETHODIMP
 nsMemoryReporterManager::Init()
 {
+#if HAVE_JEMALLOC_STATS && defined(XP_LINUX)
+    if (!jemalloc_stats)
+        return NS_ERROR_FAILURE;
+#endif
     /*
      * Register our core reporters
      */