net: Cleanup class/struct forward declarations

net/log/net_log.h

Index: net/log/net_log.h
diff --git a/net/log/net_log.h b/net/log/net_log.h
index 486e6b6fd70d4dbd63e923c4a5327c8fbe6792e8..08af4fd68a0f72973e5995b95d1af7bfcc907544 100644
--- a/net/log/net_log.h
+++ b/net/log/net_log.h
@@ -26,7 +26,6 @@
 #include "net/log/net_log_source_type.h"
 
 namespace base {
-class DictionaryValue;
 class Value;
 }