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 +1,132 @@
+// 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/gtest_prod_util.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+
+namespace base {
+class DictionaryValue;
+}
+
+class NetLogLogger;
+class ChromeNetLog;
+
+// NetLogTempFile logs all the NetLog entries into a temporary file
+// "chrome-net-export-log.json" created in file_util::GetTempDir() directory.
+//
+// NetLogTempFile maintains the current state (state_) of the logging into a
+// chrome-net-export-log.json file.
+//
+// The following are the possible states
+// a) Only Start is allowed (state_ == STATE_UNINITIALIZED).
+// b) Only Stop is allowed (state_ == STATE_ALLOW_STOP).
+// c) Either Send or Start is allowed (state_ == STATE_ALLOW_START_SEND).
+//
+// This is created/destroyed on the UI thread, but all other function calls
+// occur on the FILE_USER_BLOCKING thread.
+//
+// This relies on the UI thread outlasting all other named threads for thread
+// safety.
+class NetLogTempFile {
+ public:
+  // This enum lists the UI button commands it could receive.
+  enum Command {
+    DO_START,          // Call StartLog.
+    DO_STOP,           // Call StopLog.
+  };
+
+  virtual ~NetLogTempFile();  // Destructs a NetLogTempFile.
+
+  // Accepts the button command and executes it.
+  void ProcessCommand(Command command);
+
+  // Returns true and the path to the temporary file. If there is no file to
+  // send, then it returns false.

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

nit:  Think it's worth mentioning that it also returns false while actively
logging to the file.

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

Done.

+  bool GetFilePath(FilePath* path);
+
+  // Creates a Value summary of the state of the NetLogTempFile. The caller is
+  // responsible for deleting the returned value.
+  base::DictionaryValue* GetState();
+
+ protected:
+  // Constructs a NetLogTempFile. Only one instance is created in browser
+  // process.
+  explicit NetLogTempFile(ChromeNetLog* chrome_net_log);
+
+  // Returns the FilePath to chrome-net-export-log.json file in
+  // file_util::GetTempDir() directory in |path| argument. Returns false if
+  // ".../chrome-net-export-log.json" file doesn't exist or if
+  // file_util::GetTempDir() fails.
+  virtual bool GetNetExportLog(FilePath* path);
+
+ private:
+  friend class ChromeNetLog;
+  friend class CustomNetLogTempFile;

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

Can we just make anything thing this class accesses protected, and unfriend it? 
I prefer to friend classes only when necessary (The other friends all allow us
not to expose our innards externally.  Doesn't seem to be the case with
CustomNetLogTempFile.

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

Made NetLogTempFile and NetExportLogExists so that unit tests can call
TestNetLogTempFile's methods.

Done.

+  friend class NetLogTempFileTest;
+
+  // Allow tests to access our innards for testing purposes.
+  FRIEND_TEST_ALL_PREFIXES(NetLogTempFileTest, Init);
+  FRIEND_TEST_ALL_PREFIXES(NetLogTempFileTest, InitAllowStart);
+  FRIEND_TEST_ALL_PREFIXES(NetLogTempFileTest, InitAllowStartOrSend);
+  FRIEND_TEST_ALL_PREFIXES(NetLogTempFileTest, ProcessCommandDoStart);
+  FRIEND_TEST_ALL_PREFIXES(NetLogTempFileTest, ProcessCommandDoStop);
+  FRIEND_TEST_ALL_PREFIXES(NetLogTempFileTest, DoStartClearsFile);
+  FRIEND_TEST_ALL_PREFIXES(NetLogTempFileTest, GetFilePath);
+
+  // This enum lists the possible state NetLogTempFile could be in. It is used
+  // to enable/disable "Start", "Stop" and "Send" (email) UI actions.
+  enum State {
+    STATE_UNINITIALIZED,
+    STATE_ALLOW_START,       // Only DO_START Command is allowed.
+    STATE_ALLOW_STOP,        // Only DO_STOP Command is allowed.
+    STATE_ALLOW_START_SEND,  // Either DO_START or DO_SEND is allowed.
+  };
+
+  // Initializes the |state_| to either STATE_ALLOW_START (if there is no
+  // temporary file from earlier run) or STATE_ALLOW_START_SEND (if there is a
+  // temporary file from earlier run).
+  void Init();
+
+  // Start collecting NetLog data into chrome-net-export-log.json file in
+  // file_util::GetTempDir() directory. 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();
+
+  // Helper function for unit tests.
+  State state() const { return state_; }
+
+  FilePath log_path() const { return log_path_; }

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

Think we can get rid of this, and not depend on it or log_path_ in the tests.

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

Done.

+
+  State state_;  // Current state of NetLogTempFile.
+
+  // Name of the file. It defaults to chrome-net-export-log.json, but can be
+  // overwritten by unit tests.
+  FilePath::StringType log_filename_;
+
+  FilePath log_path_;  // FilePath to the temporary file.
+
+  // |net_log_logger_| watches the NetLog event stream, and sends all entries to
+  // the file created in StartNetLog().
+  scoped_ptr<NetLogLogger> net_log_logger_;
+
+  // The |chrome_net_log_| is owned by the browser process, cached here to avoid
+  // using global (g_browser_process).
+  ChromeNetLog* chrome_net_log_;
+
+  DISALLOW_COPY_AND_ASSIGN(NetLogTempFile);
+};
+
+#endif  // CHROME_BROWSER_NET_NET_LOG_TEMP_FILE_H_