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));
+  // 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.
   std::string json;
-  base::JSONWriter::Write(value.get(), true, &json);
-  VLOG(1) << json;
+  base::JSONWriter::Write(value.get(), false, &json);
+  if (!file_.get()) {
+    VLOG(1) << json;
+  } else {
+    fprintf(file_.get(), "%s\n", json.c_str());
+  }
 }