Reland of VCMCodecTimer: Change filter from max to 95th percentile (patchset #1 id:1 of https://codereview.webrtc.org/1808693002/ )

This CL is expected to lower goog_max_decode_ms and total_delay_incl_network/receiver_time for screenshare.

Reason for revert:
This CL did not cause the unexpected goog_encode_usage_percent and goog_avg_encode_ms perf changes.

Original issue's description:
> Revert of VCMCodecTimer: Change filter from max to 95th percentile (patchset #5 id:180001 of https://codereview.webrtc.org/1742323002/ )
>
> Reason for revert:
> Caused unexpected perf stats changes, see http://crbug/594575.
>
> Original issue's description:
> > VCMCodecTimer: Change filter from max to 95th percentile
> >
> > The purpose with this change is to make the filter more robust against anomalies. googMaxDecodeMs is expected to drop a litte by this.
> >
> > BUG=b/27306053
> >
> > Committed: https://crrev.com/4bf0c717740d1834e810ea5f32b3c4306c64235f
> > Cr-Commit-Position: refs/heads/master@{#11952}
>
> TBR=stefan@webrtc.org,philipel@webrtc.org
> # Not skipping CQ checks because original CL landed more than 1 days ago.
> BUG=594575,b/27306053
>
> Committed: https://crrev.com/c4a74e95b545f4752d4e72961ac03c1380d4bc1f
> Cr-Commit-Position: refs/heads/master@{#12018}

TBR=stefan@webrtc.org,philipel@webrtc.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=594575,b/27306053

Review URL: https://codereview.webrtc.org/1824763003

Cr-Commit-Position: refs/heads/master@{#12087}
diff --git a/webrtc/modules/video_coding/codec_timer.h b/webrtc/modules/video_coding/codec_timer.h
index 8ebd82a..90ef6bb 100644
--- a/webrtc/modules/video_coding/codec_timer.h
+++ b/webrtc/modules/video_coding/codec_timer.h
@@ -11,45 +11,39 @@
 #ifndef WEBRTC_MODULES_VIDEO_CODING_CODEC_TIMER_H_
 #define WEBRTC_MODULES_VIDEO_CODING_CODEC_TIMER_H_
 
+#include <queue>
+
 #include "webrtc/modules/include/module_common_types.h"
+#include "webrtc/modules/video_coding/percentile_filter.h"
 #include "webrtc/typedefs.h"
 
 namespace webrtc {
 
-// MAX_HISTORY_SIZE * SHORT_FILTER_MS defines the window size in milliseconds
-#define MAX_HISTORY_SIZE 10
-#define SHORT_FILTER_MS 1000
-
-class VCMShortMaxSample {
- public:
-  VCMShortMaxSample() : shortMax(0), timeMs(-1) {}
-
-  int32_t shortMax;
-  int64_t timeMs;
-};
-
 class VCMCodecTimer {
  public:
   VCMCodecTimer();
 
-  // Updates the max filtered decode time.
-  void MaxFilter(int32_t newDecodeTimeMs, int64_t nowMs);
+  // Add a new decode time to the filter.
+  void AddTiming(int64_t new_decode_time_ms, int64_t now_ms);
 
-  // Empty the list of timers.
-  void Reset();
-
-  // Get the required decode time in ms.
-  int32_t RequiredDecodeTimeMs(FrameType frameType) const;
+  // Get the required decode time in ms. It is the 95th percentile observed
+  // decode time within a time window.
+  int64_t RequiredDecodeTimeMs() const;
 
  private:
-  void UpdateMaxHistory(int32_t decodeTime, int64_t now);
-  void ProcessHistory(int64_t nowMs);
+  struct Sample {
+    Sample(int64_t decode_time_ms, int64_t sample_time_ms);
+    int64_t decode_time_ms;
+    int64_t sample_time_ms;
+  };
 
-  int32_t _filteredMax;
   // The number of samples ignored so far.
-  int32_t _ignoredSampleCount;
-  int32_t _shortMax;
-  VCMShortMaxSample _history[MAX_HISTORY_SIZE];
+  int ignored_sample_count_;
+  // Queue with history of latest decode time values.
+  std::queue<Sample> history_;
+  // |filter_| contains the same values as |history_|, but in a data structure
+  // that allows efficient retrieval of the percentile value.
+  PercentileFilter filter_;
 };
 
 }  // namespace webrtc