Consolidates accessing and setting the UMA pref to be within metrics code

chrome/browser/metrics/chrome_metrics_service_accessor.h

Index: chrome/browser/metrics/chrome_metrics_service_accessor.h
diff --git a/chrome/browser/metrics/chrome_metrics_service_accessor.h b/chrome/browser/metrics/chrome_metrics_service_accessor.h
index d64f4c6f561b026279bdb10238c57bc454bfee61..0493d6d1559970edfd50d8db853709c5fd96a414 100644
--- a/chrome/browser/metrics/chrome_metrics_service_accessor.h
+++ b/chrome/browser/metrics/chrome_metrics_service_accessor.h
@@ -8,6 +8,7 @@
 #include <stdint.h>
 #include <string>
 
+#include "base/callback.h"
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "chrome/browser/metrics/metrics_service_accessor.h"
@@ -33,6 +34,10 @@ namespace system_logs {
 class ChromeInternalLogSource;
 }
 
+namespace options {
+class BrowserOptionsHandler;
+}
+
 // This class limits and documents access to metrics service helper methods.
 // Since these methods are private, each user has to be explicitly declared
 // as a 'friend' below.
@@ -48,6 +53,9 @@ class ChromeMetricsServiceAccessor : public MetricsServiceAccessor {
   friend class ::FlashDOMHandler;
   friend class system_logs::ChromeInternalLogSource;
   friend class UmaSessionStats;
+  friend class options::BrowserOptionsHandler;
+  friend void InitiateMetricsReportingChange(bool,
+                                             const base::Callback<void(bool)>);
 
   FRIEND_TEST_ALL_PREFIXES(ChromeMetricsServiceAccessorTest,
                            MetricsReportingEnabled);