Extract guts of ChromeStabilityMetricsProvider into helper class

components/metrics/system_memory_stats_recorder.h

 // Copyright 2015 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_MEMORY_SYSTEM_MEMORY_STATS_RECORDER_H_
-#define CHROME_BROWSER_MEMORY_SYSTEM_MEMORY_STATS_RECORDER_H_
+#ifndef COMPONENTS_METRICS_SYSTEM_MEMORY_STATS_RECORDER_H_
+#define COMPONENTS_METRICS_SYSTEM_MEMORY_STATS_RECORDER_H_
 
-namespace memory {
+namespace metrics {
 
 // Record a memory size in megabytes, over a potential interval up to 32 GB.
 #define UMA_HISTOGRAM_LARGE_MEMORY_MB(name, sample) \
   UMA_HISTOGRAM_CUSTOM_COUNTS(name, sample, 1, 32768, 50)
 
 // The type of memory UMA stats to be recorded in RecordMemoryStats.
 enum RecordMemoryStatsType {
   // When a tab was discarded.
   RECORD_MEMORY_STATS_TAB_DISCARDED,
 
   // Right after the renderer for contents was killed.
   RECORD_MEMORY_STATS_CONTENTS_OOM_KILLED,
 
   // Right after the renderer for extensions was killed.
   RECORD_MEMORY_STATS_EXTENSIONS_OOM_KILLED,
 };
 
 void RecordMemoryStats(RecordMemoryStatsType type);
 
-}  // namespace memory
+}  // namespace metrics
 
-#endif  // CHROME_BROWSER_MEMORY_SYSTEM_MEMORY_STATS_RECORDER_H_
+#endif  // COMPONENTS_METRICS_SYSTEM_MEMORY_STATS_RECORDER_H_