Extracting NetLog inner classes into their own classes.

components/net_log/net_log_file_writer.h

Index: components/net_log/net_log_file_writer.h
diff --git a/components/net_log/net_log_file_writer.h b/components/net_log/net_log_file_writer.h
index fb82d3ec84e4d306948eb8fa7df2afaefef89f8d..17033e624b8aecf4f56e1f3c96b540875943445b 100644
--- a/components/net_log/net_log_file_writer.h
+++ b/components/net_log/net_log_file_writer.h
@@ -13,13 +13,13 @@
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/threading/thread_checker.h"
-#include "net/log/net_log.h"
 
 namespace base {
 class DictionaryValue;
 }
 
 namespace net {
+class NetLogCaptureMode;
 class WriteToFileNetLogObserver;
 }