Move RedirectChromeLogging to src/chromeos.

chrome/browser/chromeos/logging.cc

+// Copyright 2017 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/chromeos/logging.h"
+
+#include "base/command_line.h"
+#include "base/files/file_path.h"
+#include "base/logging.h"
+#include "chrome/common/logging_chrome.h"
+
+namespace logging {
+
+void RedirectChromeLogging(const base::CommandLine& command_line) {
+  // This should be true for exactly the period between the end of
+  // InitChromeLogging() and the beginning of CleanupChromeLogging().
+  static bool chrome_logging_redirected_ = false;
+  if (chrome_logging_redirected_) {
+    // TODO: Support multiple active users. http://crbug.com/230345
+    LOG(WARNING) << "NOT redirecting logging for multi-profiles case.";
+    return;
+  }
+
+  DCHECK(!chrome_logging_redirected_)
+      << "Attempted to redirect logging when it was already initialized.";
+
+  // Redirect logs to the session log directory, if set.  Otherwise
+  // defaults to the profile dir.
+  const base::FilePath log_path = GetSessionLogFile(command_line);
+
+  // Always force a new symlink when redirecting.
+  const base::FilePath target_path = SetUpSymlinkIfNeeded(log_path, true);
+
+  // ChromeOS always logs through the symlink, so it shouldn't be
+  // deleted if it already exists.
+  logging::LoggingSettings settings;
+  settings.logging_dest = DetermineLoggingDestination(command_line);
+  settings.log_file = log_path.value().c_str();
+  if (!logging::InitLogging(settings)) {

[xiyuan, 2017/05/31 15:32:22]

Would logging::InitLogging be safe to be called from a thread other than the
main thread? 

[achuithb, 2017/05/31 23:42:45]

Done.

+    DLOG(ERROR) << "Unable to initialize logging to " << log_path.value();
+    RemoveSymlinkAndLog(log_path, target_path);
+  } else {
+    chrome_logging_redirected_ = true;
+  }
+}
+
+}  // namespace logging