Refactor net::NetLog to provide implementation of observer pattern, not just the interface.

net/tools/gdig/gdig.cc

Index: net/tools/gdig/gdig.cc
diff --git a/net/tools/gdig/gdig.cc b/net/tools/gdig/gdig.cc
index 164040831eb3d679297bb0873ef2fd7715b081db..7cbb9a4922892e3d39b50af644c1f79a016a311d 100644
--- a/net/tools/gdig/gdig.cc
+++ b/net/tools/gdig/gdig.cc
@@ -182,6 +182,7 @@ bool LoadReplayLog(const base::FilePath& file_path, ReplayLog* replay_log) {
 class GDig {
  public:
   GDig();
+  ~GDig();
 
   enum Result {
     RESULT_NO_RESOLVE = -3,
@@ -219,7 +220,8 @@ class GDig {
 
   base::CancelableClosure timeout_closure_;
   scoped_ptr<DnsConfigService> dns_config_service_;
-  scoped_ptr<FileNetLog> log_;
+  scoped_ptr<FileNetLogObserver> log_observer_;
+  scoped_ptr<NetLog> log_;
   scoped_ptr<HostResolver> resolver_;
 };
 
@@ -232,6 +234,11 @@ GDig::GDig()
       active_resolves_(0) {
 }
 
+GDig::~GDig() {
+  if (log_)
+    log_->RemoveThreadSafeObserver(log_observer_.get());
+}
+
 GDig::Result GDig::Main(int argc, const char* argv[]) {
   if (!ParseCommandLine(argc, argv)) {
       fprintf(stderr,
@@ -299,7 +306,9 @@ bool GDig::ParseCommandLine(int argc, const char* argv[]) {
         return false;
       }
     }
-    log_.reset(new FileNetLog(stderr, level));
+    log_.reset(new NetLog);
+    log_observer_.reset(new FileNetLogObserver(stderr));
+    log_->AddThreadSafeObserver(log_observer_.get(), level);
   }
 
   print_config_ = parsed_command_line.HasSwitch("print_config");