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

chrome/browser/net/net_log_temp_file.h

Index: chrome/browser/net/net_log_temp_file.h
===================================================================
--- chrome/browser/net/net_log_temp_file.h	(revision 0)
+++ chrome/browser/net/net_log_temp_file.h	(revision 0)
@@ -0,0 +1,97 @@
+// Copyright (c) 2012 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.
+
+#ifndef CHROME_BROWSER_NET_NET_LOG_TEMP_FILE_H_
+#define CHROME_BROWSER_NET_NET_LOG_TEMP_FILE_H_
+
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/file_path.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/singleton.h"
+#include "base/memory/weak_ptr.h"
+
+namespace base {
+class Value;
+}
+
+class NetLogLogger;
+
+// NetLogTempFile logs all the net_log entries into a temporary file created in
+// "NetLogs" folder in file_util::GetTempDir() directory.
+//
+// NetLogTempFile is a singleton that maintains the current state (state_) of
+// the logging into a temporary file.
+//
+// The following are the possible states
+// a) Only Start is allowed (state_ == UNINITIALIZED).
+// b) Only Stop is allowed (state_ == STOP).
+// c) Either Send or Start is allowed (state_ == START_SEND).
+class NetLogTempFile {
+ public:
+  // This enum lists the possible state NetLogTempFile could be in.
+  enum Command {
+    DO_START,          // Call StartLog.
+    DO_STOP,           // Call StopLog.
+    DO_SEND,           // Call SendLog.
+  };
+
+  // This enum lists the possible state NetLogTempFile could be in.
+  enum State {
+    UNINITIALIZED,
+    START,          // Only StartLog is allowed.
+    STOP,           // Only StopLog is allowed.
+    START_SEND,     // Either OnSendLog or OnStartLog calls are allowed.
+  };
+
+  static NetLogTempFile* GetInstance();

[mmenke, 2012/12/27 20:43:05]

What's the motivation for making this a Singleton?

[ramant (doing other things), 2013/01/04 01:47:28]

Made it a single to work with chrome://net-internals being opened in multiple
tabs.

[mmenke, 2013/01/04 16:22:09]

How much do we care about that use case?  I've been instilled with a dislike of
singletons unless absolutely necessary, and I'm not convinced it's absolutely
necessary here.

If we're really concerned about it, there's only one ChromeNetLog, and we could
expose these functions there instead, or have it own the NetLogTempFile, and
expose it directly.

+
+  // Constructs a NetLogTempFile. Only one instance is created in
+  // browser process.
+  NetLogTempFile();
+  ~NetLogTempFile();

[mmenke, 2012/12/27 20:43:05]

If we're going to make this a Singleton, these should be private (You've already
friended DefaultSingletonTraits, as you would need to).

[ramant (doing other things), 2013/01/04 01:47:28]

Done.

+
+  void ProcessCommand(Command command);
+
+  // Creates a Value summary of the state of the NetLogTempFile. The caller is
+  // responsible for deleting the returned value.
+  base::Value* NetLogTempFileToValue() const;
+
+ private:
+  friend struct DefaultSingletonTraits<NetLogTempFile>;
+
+  // Initializes the |state_| to either START (if there is no
+  // temporary file from earlier run) or START_SEND (if there is a
+  // temporary file from earlier run).
+  void DetermineInitialState();
+
+  // Start collecting NetLog data into a temporary file in "NetLogs" folder in
+  // file_util::GetTempDir() directory. It deletes all the temporary files that
+  // are in that directory before creating a new temporary file. It is a no-op
+  // if we are already collecting data into a file.
+  void StartNetLog();
+
+  // Stop collecting NetLog data into the temporary file. It is a no-op if we
+  // are not collecting data into a file.
+  void StopNetLog();
+
+  // Emails the temporary file if one exists.
+  void SendNetLog();
+
+  // Send NetLog via email.
+  static void SendEmail(const FilePath& file_to_send);
+
+  State state_;  // Current state of NetLogTempFile.
+
+  FilePath log_path_;  // FilePath to the temporary file.
+
+  // |net_log_logger_| watches the NetLog event stream, and sends all entries to
+  // the temporary file created in StartNetLog().
+  scoped_ptr<NetLogLogger> net_log_logger_;
+
+  DISALLOW_COPY_AND_ASSIGN(NetLogTempFile);
+};
+
+#endif  // CHROME_BROWSER_NET_NET_LOG_TEMP_FILE_H_