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 +1,92 @@
+// 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.
+
+#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"
+
+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 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_ == ALLOW_STOP).
+// c) Either Send or Start is allowed (state_ == ALLOW_START_SEND).

[mmenke, 2013/01/11 18:31:12]

Think it's worth mentioning this is created/destroyed on the UI thread, but all
other function calls occur on the FILE_USER_BLOCKING thread.

And that this relies on the UI thread outlasting all other named threads for
thread safety.

[ramant (doing other things), 2013/01/12 04:34:04]

Done.

+class NetLogTempFile {
+ public:
+  // This enum lists the UI button commands it could receive.
+  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 {

[mmenke, 2013/01/11 18:31:12]

Since these aren't used externally, this should be in the private section.

[ramant (doing other things), 2013/01/12 04:34:04]

Done.

+    UNINITIALIZED,
+    ALLOW_START,          // Only StartLog is allowed.
+    ALLOW_STOP,           // Only StopLog is allowed.
+    ALLOW_START_SEND,     // Either OnSendLog or OnStartLog calls are allowed.

[mmenke, 2013/01/11 18:31:12]

Suggest naming the state after what |this| is currently doing, rather than what
commands it allows.

Something along the lines of:

"STATE_UNINITIALIZED",
"STATE_LOGGING",
"STATE_STOPPED_NO_LOG",  (Or STATE_NEVER_STARTED)
"STATE_STOPPED_HAS_LOG"

[ramant (doing other things), 2013/01/12 04:34:04]

Added STATE_ to the names. Updated the comments to show how it is being used
internally. Would like to talk to you more about better names. thanks.

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

[mmenke, 2013/01/11 18:31:12]

Given how weirdly this class will behave if we have more than one of them, may
be worth making these private and friending ChromeNetLog.  Not a huge fan of
friending, but prefer it to making a class that's fragile.

[ramant (doing other things), 2013/01/12 04:34:04]

left ~NetLogTempFile() as public because of scoped_ptr. Is that ok? Is there a
better way to do this?
Done.

[mmenke, 2013/01/17 17:49:43]

You could friend the relevant class if you really wanted, but I think this is
fine.  Only construction we really want to protect against.

+
+  // Accepts the button command and executes them.
+  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();

[mmenke, 2013/01/11 18:31:12]

Suggest renaming this "GetStateAsValue()" or even just "GetState()", since
there's no other way of getting the current state.

[ramant (doing other things), 2013/01/12 04:34:04]

Done.

+
+ private:
+  // Initializes the |state_| to either ALLOW_START (if there is no temporary
+  // file from earlier run) or ALLOW_START_SEND (if there is a temporary file
+  // from earlier run).
+  void Init();
+
+  // 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();
+
+  // Helper function that runs on UI thread to send NetLog data 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_