Extracted NetLog class's inner enum types into their own enum classes and

extensions/browser/extension_throttle_manager.cc

Index: extensions/browser/extension_throttle_manager.cc
diff --git a/extensions/browser/extension_throttle_manager.cc b/extensions/browser/extension_throttle_manager.cc
index c4b4ab92d0282bdb32dff809d96348b70fbf29a5..22a7de680a9f20f9ea5711976d5c083e7064d762 100644
--- a/extensions/browser/extension_throttle_manager.cc
+++ b/extensions/browser/extension_throttle_manager.cc
@@ -15,6 +15,8 @@
 #include "extensions/common/constants.h"
 #include "net/base/url_util.h"
 #include "net/log/net_log.h"
+#include "net/log/net_log_event_type.h"
+#include "net/log/net_log_source_type.h"
 #include "net/url_request/url_request.h"
 
 namespace extensions {
@@ -104,7 +106,7 @@ ExtensionThrottleManager::RegisterRequestUrl(const GURL& url) {
     if (net::IsLocalhost(host)) {
       if (!logged_for_localhost_disabled_ && net::IsLocalhost(host)) {
         logged_for_localhost_disabled_ = true;
-        net_log_.AddEvent(net::NetLog::TYPE_THROTTLING_DISABLED_FOR_HOST,
+        net_log_.AddEvent(net::NetLogEventType::THROTTLING_DISABLED_FOR_HOST,
                           net::NetLog::StringCallback("host", &host));
       }
 
@@ -157,7 +159,7 @@ bool ExtensionThrottleManager::enable_thread_checks() const {
 void ExtensionThrottleManager::set_net_log(net::NetLog* net_log) {
   DCHECK(net_log);
   net_log_ = net::BoundNetLog::Make(
-      net_log, net::NetLog::SOURCE_EXPONENTIAL_BACKOFF_THROTTLING);
+      net_log, net::NetLogSourceType::EXPONENTIAL_BACKOFF_THROTTLING);
 }
 
 net::NetLog* ExtensionThrottleManager::net_log() const {