Break out histogram counter variables as CookieMonster instance variables.

net/base/cookie_monster.h

Index: net/base/cookie_monster.h
diff --git a/net/base/cookie_monster.h b/net/base/cookie_monster.h
index 4986cd4aecb653a459d555547e144d00c769ea59..96d98b3f879387e50f998eb4d1afa9b9eaa5b84e 100644
--- a/net/base/cookie_monster.h
+++ b/net/base/cookie_monster.h
@@ -72,6 +72,7 @@ class CookieMonster : public CookieStore {
             last_access_threshold_milliseconds)),
         delegate_(delegate),
         last_statistic_record_time_(base::Time::Now()) {
+    InitializeHistograms();
     SetDefaultCookieableSchemes();
   }
 #endif
@@ -287,6 +288,19 @@ class CookieMonster : public CookieStore {
   // statistics if a sufficient time period has passed.
   void RecordPeriodicStats(const base::Time& current_time);
 
+  // Histogram variables; see CookieMonster::InitializeHistograms() in
+  // cookie_monster.cc for details.
+  scoped_refptr<Histogram> histogram_expiration_duration_minutes_;
+  scoped_refptr<Histogram> histogram_between_access_interval_minutes_;
+  scoped_refptr<Histogram> histogram_evicted_last_access_minutes_;
+  scoped_refptr<Histogram> histogram_count_;
+  scoped_refptr<Histogram> histogram_number_duplicate_db_cookies_;
+  scoped_refptr<Histogram> histogram_cookie_deletion_cause_;
+
+  // Initialize the above variables; should only be called from
+  // the constructor.
+  void InitializeHistograms();
+
   CookieMap cookies_;
 
   // Indicates whether the cookie store has been initialized. This happens