metrics: Add leak detector controller in Chrome OS metrics system

chrome/common/chrome_features.cc

 // Copyright 2016 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/common/chrome_features.h"
 
 namespace features {
 
 // All features in alphabetical order.
 
 #if defined(OS_WIN) || defined(OS_MACOSX)
 // Enables automatic tab discarding, when the system is in low memory state.
 const base::Feature kAutomaticTabDiscarding{"AutomaticTabDiscarding",
                                             base::FEATURE_DISABLED_BY_DEFAULT};
 #endif  // defined(OS_WIN) || defined(OS_MACOSX)
 
 #if defined(GOOGLE_CHROME_BUILD) && defined(OS_LINUX) && !defined(OS_CHROMEOS)
 // Enables showing the "This computer will no longer receive Google Chrome
 // updates" infobar instead of the "will soon stop receiving" infobar on
 // deprecated systems.
 const base::Feature kLinuxObsoleteSystemIsEndOfTheLine{
     "LinuxObsoleteSystemIsEndOfTheLine", base::FEATURE_DISABLED_BY_DEFAULT};
 #endif
 
+#if defined(OS_CHROMEOS)
+// Runtime flag that indicates whether this leak detector should be enabled in
+// the current instance of Chrome.
+const base::Feature kRuntimeMemoryLeakDetector{
+    "RuntimeMemoryLeakDetector", base::FEATURE_DISABLED_BY_DEFAULT};
+#endif  // defined(OS_CHROMEOS)
+
 }  // namespace features