First cut at UI for saving net_logs data into a temporary file on

chrome/browser/net/net_log_temp_file.cc

+// Copyright (c) 2013 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_temp_file.h"
+
+#include "base/file_util.h"
+#include "base/values.h"
+#include "chrome/browser/net/chrome_net_log.h"
+#include "chrome/browser/net/net_log_logger.h"
+
+NetLogTempFile::NetLogTempFile(ChromeNetLog* chrome_net_log)
+    : state_(STATE_UNINITIALIZED),
+      log_filename_(FILE_PATH_LITERAL("chrome-net-export-log.json")),
+      chrome_net_log_(chrome_net_log) {
+}
+
+NetLogTempFile::~NetLogTempFile() {
+  if (net_log_logger_.get())
+    net_log_logger_->StopObserving();
+}
+
+void NetLogTempFile::ProcessCommand(Command command) {

[mmenke, 2013/01/23 19:01:27]

Think you should DCHECK that all of these are called on the right thread.  Can
just use TestBrowserThread to get the unit tests passing.

[ramant (doing other things), 2013/01/24 03:23:55]

Done.

+  // Determine the state_ if it is not set.
+  if (state_ == STATE_UNINITIALIZED)
+    Init();
+
+  switch (command) {
+    case DO_START:
+      StartNetLog();
+      break;
+    case DO_STOP:
+      StopNetLog();
+      break;
+    default:
+      break;
+  }
+}
+
+DictionaryValue* NetLogTempFile::GetState() {
+  // Determine the state_ if it is not set.
+  if (state_ == STATE_UNINITIALIZED)
+    Init();
+
+  base::DictionaryValue* dict = new base::DictionaryValue;
+
+#ifndef NDEBUG
+  dict->SetString("file", log_path_.MaybeAsASCII());

[mmenke, 2013/01/23 19:01:27]

nit:  Maybe LossyDisplayName() would be better?

[ramant (doing other things), 2013/01/24 03:23:55]

Done.

+#endif  // NDEBUG
+
+  switch (state_) {
+    case STATE_ALLOW_STOP:
+      dict->SetString("state", "ALLOW_STOP");
+      break;
+    case STATE_ALLOW_START_SEND:
+      dict->SetString("state", "ALLOW_START_SEND");
+      break;
+    default:
+      dict->SetString("state", "ALLOW_START");
+      break;
+  }
+  return dict;
+}
+
+void NetLogTempFile::Init() {
+  if (state_ != STATE_UNINITIALIZED)
+    return;
+
+  if (GetNetExportLog(&log_path_))
+    state_ = STATE_ALLOW_START_SEND;
+  else
+    state_ = STATE_ALLOW_START;

[mmenke, 2013/01/23 19:01:27]

If file_util::GetTempDir fails, we'll end up in STATE_ALLOW_START with an
invalid log_path_.  If we want to handle GetTempDir failures correctly, we'll
need to slightly rework things.

My suggestion:  Separate out getting the path and checking if the file exists,
using different virtual functions for each.  Then STATE_ALLOW_START can just
call GetNetExportLog (And update log_path_), and if it fails, indicating no temp
directory, exit early without changing the state.

GetFilePath would then just call the function to check for file existence with
log_path_ and just copy log_path_ to path, which I think is a little cleaner as
well.

[ramant (doing other things), 2013/01/24 03:23:55]

Done.

+}
+
+void NetLogTempFile::StartNetLog() {
+  if (state_ == STATE_ALLOW_STOP)
+    return;
+
+  // Try to make sure we can create the file.
+  // TODO(rtenneti): Find a better for doing the following.
+  FILE* fp = file_util::OpenFile(log_path_, "w");
+  if (!fp)
+    return;
+  file_util::CloseFile(fp);
+
+  net_log_logger_.reset(new NetLogLogger(log_path_));
+  net_log_logger_->StartObserving(chrome_net_log_);
+  state_ = STATE_ALLOW_STOP;
+}
+
+void NetLogTempFile::StopNetLog() {
+  if (state_ != STATE_ALLOW_STOP)
+    return;
+
+  net_log_logger_->StopObserving();
+  net_log_logger_.reset();
+  state_ = STATE_ALLOW_START_SEND;
+}
+
+bool NetLogTempFile::GetFilePath(FilePath* path) {
+  if (state_ != STATE_ALLOW_START_SEND)
+    return false;
+
+  FilePath net_export_log;
+  if (!GetNetExportLog(&net_export_log))
+    return false;
+
+#if defined(OS_POSIX)
+  // Users, group and others can read, write and traverse.
+  int mode = file_util::FILE_PERMISSION_MASK;
+  file_util::SetPosixFilePermissions(net_export_log, mode);
+#endif  // defined(OS_POSIX)
+
+  *path = net_export_log;
+  return true;
+}
+
+bool NetLogTempFile::GetNetExportLog(FilePath* path) {
+  FilePath temp_dir;
+  if (!file_util::GetTempDir(&temp_dir))
+    return false;
+
+  *path = temp_dir.Append(log_filename_);
+  return file_util::PathExists(*path);
+}