Remove the unmaintained performance monitor.

chrome/browser/performance_monitor/constants.cc

Index: chrome/browser/performance_monitor/constants.cc
diff --git a/chrome/browser/performance_monitor/constants.cc b/chrome/browser/performance_monitor/constants.cc
deleted file mode 100644
index b39f0d3975822cdfe1c6ef64376d220e00f13428..0000000000000000000000000000000000000000
--- a/chrome/browser/performance_monitor/constants.cc
+++ /dev/null
@@ -1,24 +0,0 @@
-// 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.
-
-#include "chrome/browser/performance_monitor/constants.h"
-
-namespace performance_monitor {
-
-// The error message displayed when a metric's details are not found.
-const char kMetricNotFoundError[] = "Metric details not found.";
-
-// Any metric that is not associated with a specific activity will use this as
-// its activity.
-const char kProcessChromeAggregate[] = "chrome_aggregate";
-
-// Tokens to retrieve state values from the database.
-
-// Stores information about the previous chrome version.
-const char kStateChromeVersion[] = "chrome_version";
-// The prefix to the state of a profile's name, to prevent any possible naming
-// collisions in the database.
-const char kStateProfilePrefix[] = "profile";
-
-}  // namespace performance_monitor