[Metrics] Make MetricsStateManager take a callback param to check if UMA is enabled.

chrome/common/chrome_switches.h

 // 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.
 
 // Defines all the command-line switches used by Chrome.
 
 #ifndef CHROME_COMMON_CHROME_SWITCHES_H_
 #define CHROME_COMMON_CHROME_SWITCHES_H_
 
 #include "build/build_config.h"
@@ skipping 134 matching lines @@
 extern const char kEnableDomainReliability[];
 extern const char kEnableEasyUnlock[];
 extern const char kEnableEnhancedBookmarks[];
 extern const char kEnableEphemeralApps[];
 extern const char kEnableExtensionActivityLogging[];
 extern const char kEnableExtensionActivityLogTesting[];
 extern const char kEnableFastUnload[];
 extern const char kEnableIPv6[];
 extern const char kEnableLinkableEphemeralApps[];
 extern const char kEnableManagedStorage[];
-extern const char kEnableMetricsReportingForTesting[];
 extern const char kEnableNaCl[];
 extern const char kEnableNetBenchmarking[];
 extern const char kEnableNetworkTime[];
 extern const char kEnableNpnHttpOnly[];
 extern const char kEnableOfflineAutoReload[];
 extern const char kEnableOfflineLoadStaleCache[];
 extern const char kDisableOfflineLoadStaleCache[];
 extern const char kEnableOriginChip[];
 extern const char kEnableOriginChipLeadingLocationBar[];
 extern const char kEnableOriginChipTrailingLocationBar[];
@@ skipping 254 matching lines @@
 #else
 extern const char kEnablePrintPreview[];
 #endif
 
 // DON'T ADD RANDOM STUFF HERE. Put it in the main section above in
 // alphabetical order, or in one of the ifdefs (also in order in each section).
 
 }  // namespace switches
 
 #endif  // CHROME_COMMON_CHROME_SWITCHES_H_