Adds the ability to load JSON log files to about:net-internals.

chrome/browser/net/net_log_logger.cc

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/net/net_log_logger.h"
 
+#include <stdio.h>
+
+#include "base/file_util.h"
 #include "base/json/json_writer.h"
+#include "base/threading/thread_restrictions.h"
 #include "base/values.h"
 
-NetLogLogger::NetLogLogger()
+NetLogLogger::NetLogLogger(const FilePath &log_path)
     : ThreadSafeObserver(net::NetLog::LOG_ALL_BUT_BYTES) {
+  if (!log_path.empty()) {
+    base::ThreadRestrictions::ScopedAllowIO allow_io;
+    file_.Set(file_util::OpenFile(log_path, "w"));
+  }
 }
 
 NetLogLogger::~NetLogLogger() {}
 
 void NetLogLogger::OnAddEntry(net::NetLog::EventType type,
                               const base::TimeTicks& time,
                               const net::NetLog::Source& source,
                               net::NetLog::EventPhase phase,
                               net::NetLog::EventParameters* params) {
   scoped_ptr<Value> value(net::NetLog::EntryToDictionaryValue(type, time,
                                                               source, phase,
                                                               params, true));
   std::string json;
-  base::JSONWriter::Write(value.get(), true, &json);
-  VLOG(1) << json;
+  if (!file_.get()) {
+    base::JSONWriter::Write(value.get(), true, &json);

[eroman, 2011/01/12 05:57:34]

I don't think we should do pretty printing anymore.

How about simply doing one per line in both cases?

(having it one per line makes it easier to dump inline in the log, then extract
it from the output and feed it into the net-internals import to visualize in the
same manner.)

[mmenke, 2011/01/13 03:45:29]

Sounds reasonable.  Done.

+    VLOG(1) << json;
+  } else {
+    // Don't pretty print, so each JSON value occupies a single line, with no
+    // breaks (Line breaks in any text field will be escaped).  Using strings
+    // instead of integer identifiers allows logs from older versions to be
+    // loaded, though a little extra parsing has to be done when loading a log.
+    base::JSONWriter::Write(value.get(), false, &json);
+    fprintf(file_.get(), "%s\n", json.c_str());
+  }
 }