Templatize percentile_filter.h and move it to base/analytics.

webrtc/modules/video_coding/codec_timer.cc

Index: webrtc/modules/video_coding/codec_timer.cc
diff --git a/webrtc/modules/video_coding/codec_timer.cc b/webrtc/modules/video_coding/codec_timer.cc
index 0fdf1a692e438137c23fa69f3611936d7bb10848..b6fec0edbedae6f76a16316456a7b55369b0193e 100644
--- a/webrtc/modules/video_coding/codec_timer.cc
+++ b/webrtc/modules/video_coding/codec_timer.cc
@@ -34,13 +34,13 @@ void VCMCodecTimer::AddTiming(int64_t decode_time_ms, int64_t now_ms) {
   }
 
   // Insert new decode time value.
-  filter_.Insert(decode_time_ms);
+  filter_.Push(decode_time_ms);
   history_.emplace(decode_time_ms, now_ms);
 
   // Pop old decode time values.
   while (!history_.empty() &&
          now_ms - history_.front().sample_time_ms > kTimeLimitMs) {
-    filter_.Erase(history_.front().decode_time_ms);
+    filter_.Pop();
     history_.pop();
   }
 }