Switch cc::RollingTimeDeltaHistory to use a single deque

cc/base/rolling_time_delta_history.h

Index: cc/base/rolling_time_delta_history.h
diff --git a/cc/base/rolling_time_delta_history.h b/cc/base/rolling_time_delta_history.h
index 61ed339f74038ca8336769a9758a59641b79cba2..16cf4854a82851c6410b5084f7474640915dbd60 100644
--- a/cc/base/rolling_time_delta_history.h
+++ b/cc/base/rolling_time_delta_history.h
@@ -8,7 +8,6 @@
 #include <stddef.h>
 
 #include <deque>
-#include <set>
 
 #include "base/macros.h"
 #include "base/time/time.h"
@@ -33,10 +32,7 @@ class CC_EXPORT RollingTimeDeltaHistory {
   base::TimeDelta Percentile(double percent) const;
 
  private:
-  typedef std::multiset<base::TimeDelta> TimeDeltaMultiset;
-
-  TimeDeltaMultiset sample_set_;
-  std::deque<TimeDeltaMultiset::iterator> chronological_sample_deque_;
+  std::deque<base::TimeDelta> chronological_sample_deque_;
   size_t max_size_;
 
   DISALLOW_COPY_AND_ASSIGN(RollingTimeDeltaHistory);