First pass at adding http/backend cache to NetLog

net/base/capturing_net_log.h

Index: net/base/capturing_net_log.h
===================================================================
--- net/base/capturing_net_log.h	(revision 70512)
+++ net/base/capturing_net_log.h	(working copy)
@@ -61,6 +61,8 @@
 
   void Clear();
 
+  void SetLogLevel(NetLog::LogLevel log_level);
+
  private:
   // Needs to be "mutable" so can use it in GetEntries().
   mutable Lock lock_;
@@ -71,6 +73,8 @@
   size_t max_num_entries_;
   EntryList entries_;
 
+  NetLog::LogLevel log_level_;
+
   DISALLOW_COPY_AND_ASSIGN(CapturingNetLog);
 };
 
@@ -97,6 +101,9 @@
 
   void Clear();
 
+  // Sets the log level of the underlying CapturingNetLog.
+  void SetLogLevel(NetLog::LogLevel log_level);
+
  private:
   NetLog::Source source_;
   scoped_ptr<CapturingNetLog> capturing_net_log_;