Add some instrumentation to investigate a possible UAF.

net/base/net_log.h

Index: net/base/net_log.h
diff --git a/net/base/net_log.h b/net/base/net_log.h
index 5fb27917aba09cb0ec5f63990a39f78aa83a43bf..b78f8686c1d03b4155700314630b8cbcfae32ed8 100644
--- a/net/base/net_log.h
+++ b/net/base/net_log.h
@@ -7,10 +7,22 @@
 
 #include <string>
 
+#include "build/build_config.h"
+
+// TODO(eroman): Temporary while investigating crbug.com/467797.
+//               Note base::Debug::StackTrace() is not supported in NACL builds
+//               so conditionally disabled it there.
+#ifndef OS_NACL
+#define TEMP_INSTRUMENTATION_467797
+#endif
+
 #include "base/atomicops.h"
 #include "base/basictypes.h"
 #include "base/callback_forward.h"
 #include "base/compiler_specific.h"
+#ifdef TEMP_INSTRUMENTATION_467797
+#include "base/debug/stack_trace.h"
+#endif
 #include "base/observer_list.h"
 #include "base/strings/string16.h"
 #include "base/synchronization/lock.h"
@@ -332,6 +344,7 @@ class NET_EXPORT NetLog {
 class NET_EXPORT BoundNetLog {
  public:
   BoundNetLog() : net_log_(NULL) {}
+  ~BoundNetLog();
 
   // Add a log entry to the NetLog for the bound source.
   void AddEntry(NetLog::EventType type, NetLog::EventPhase phase) const;
@@ -388,12 +401,29 @@ class NET_EXPORT BoundNetLog {
   NetLog* net_log() const { return net_log_; }
 
  private:
+#ifdef TEMP_INSTRUMENTATION_467797
+  // TODO(eroman): Temporary while investigating crbug.com/467797
+  enum Liveness {
+    ALIVE = 0xCA11AB13,
+    DEAD = 0xDEADBEEF,
+  };
+#endif
+
   BoundNetLog(const NetLog::Source& source, NetLog* net_log)
       : source_(source), net_log_(net_log) {
   }
 
+  // TODO(eroman): Temporary while investigating crbug.com/467797
+  void CrashIfInvalid() const;
+
   NetLog::Source source_;
   NetLog* net_log_;
+
+#ifdef TEMP_INSTRUMENTATION_467797
+  // TODO(eroman): Temporary while investigating crbug.com/467797
+  Liveness liveness_ = ALIVE;
+  base::debug::StackTrace stack_trace_;
+#endif
 };
 
 }  // namespace net