Move sample_counter.h to webrtc namespace

Bug: webrtc:42232595
Change-Id: I774efbe2bbe5d29e7eac500acf1fa4c99ebc74a8
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/378041
Commit-Queue: Evan Shrubsole <eshr@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#43936}
diff --git a/rtc_base/numerics/sample_counter.cc b/rtc_base/numerics/sample_counter.cc
index 50e9f2a..c76e609 100644
--- a/rtc_base/numerics/sample_counter.cc
+++ b/rtc_base/numerics/sample_counter.cc
@@ -17,7 +17,7 @@
 #include "rtc_base/checks.h"
 #include "rtc_base/numerics/safe_conversions.h"
 
-namespace rtc {
+namespace webrtc {
 
 SampleCounter::SampleCounter() = default;
 SampleCounter::~SampleCounter() = default;
@@ -117,4 +117,4 @@
   *this = {};
 }
 
-}  // namespace rtc
+}  // namespace webrtc
diff --git a/rtc_base/numerics/sample_counter.h b/rtc_base/numerics/sample_counter.h
index fa58ce1..767b868 100644
--- a/rtc_base/numerics/sample_counter.h
+++ b/rtc_base/numerics/sample_counter.h
@@ -15,7 +15,7 @@
 
 #include <optional>
 
-namespace rtc {
+namespace webrtc {
 
 // Simple utility class for counting basic statistics (max./avg./variance) on
 // stream of samples.
@@ -56,5 +56,12 @@
   int64_t sum_squared_ = 0;
 };
 
+}  //  namespace webrtc
+
+// Re-export symbols from the webrtc namespace for backwards compatibility.
+// TODO(bugs.webrtc.org/4222596): Remove once all references are updated.
+namespace rtc {
+using ::webrtc::SampleCounter;
+using ::webrtc::SampleCounterWithVariance;
 }  // namespace rtc
 #endif  // RTC_BASE_NUMERICS_SAMPLE_COUNTER_H_
diff --git a/rtc_base/numerics/sample_counter_unittest.cc b/rtc_base/numerics/sample_counter_unittest.cc
index 82e61fd..64ef6ca 100644
--- a/rtc_base/numerics/sample_counter_unittest.cc
+++ b/rtc_base/numerics/sample_counter_unittest.cc
@@ -18,7 +18,7 @@
 
 using ::testing::Eq;
 
-namespace rtc {
+namespace webrtc {
 
 TEST(SampleCounterTest, ProcessesNoSamples) {
   constexpr int kMinSamples = 1;
@@ -82,4 +82,4 @@
   EXPECT_THAT(counter1.Variance(kMinSamples), Eq(2));
 }
 
-}  // namespace rtc
+}  // namespace webrtc
diff --git a/video/receive_statistics_proxy.h b/video/receive_statistics_proxy.h
index 7af28fd..2c11c0f 100644
--- a/video/receive_statistics_proxy.h
+++ b/video/receive_statistics_proxy.h
@@ -129,7 +129,7 @@
 
  private:
   struct QpCounters {
-    rtc::SampleCounter vp8;
+    SampleCounter vp8;
   };
 
   struct ContentSpecificStats {
@@ -138,13 +138,13 @@
 
     void Add(const ContentSpecificStats& other);
 
-    rtc::SampleCounter e2e_delay_counter;
-    rtc::SampleCounter interframe_delay_counter;
+    SampleCounter e2e_delay_counter;
+    SampleCounter interframe_delay_counter;
     int64_t flow_duration_ms = 0;
     int64_t total_media_bytes = 0;
-    rtc::SampleCounter received_width;
-    rtc::SampleCounter received_height;
-    rtc::SampleCounter qp_counter;
+    SampleCounter received_width;
+    SampleCounter received_height;
+    SampleCounter qp_counter;
     FrameCounts frame_counts;
     rtc::HistogramPercentileCounter interframe_delay_percentiles;
     webrtc_impl::RunningStatistics<double> corruption_score;
@@ -168,12 +168,12 @@
   RateStatistics renders_fps_estimator_ RTC_GUARDED_BY(main_thread_);
   rtc::RateTracker render_fps_tracker_ RTC_GUARDED_BY(main_thread_);
   rtc::RateTracker render_pixel_tracker_ RTC_GUARDED_BY(main_thread_);
-  rtc::SampleCounter sync_offset_counter_ RTC_GUARDED_BY(main_thread_);
-  rtc::SampleCounter decode_time_counter_ RTC_GUARDED_BY(main_thread_);
-  rtc::SampleCounter jitter_delay_counter_ RTC_GUARDED_BY(main_thread_);
-  rtc::SampleCounter target_delay_counter_ RTC_GUARDED_BY(main_thread_);
-  rtc::SampleCounter current_delay_counter_ RTC_GUARDED_BY(main_thread_);
-  rtc::SampleCounter oneway_delay_counter_ RTC_GUARDED_BY(main_thread_);
+  SampleCounter sync_offset_counter_ RTC_GUARDED_BY(main_thread_);
+  SampleCounter decode_time_counter_ RTC_GUARDED_BY(main_thread_);
+  SampleCounter jitter_delay_counter_ RTC_GUARDED_BY(main_thread_);
+  SampleCounter target_delay_counter_ RTC_GUARDED_BY(main_thread_);
+  SampleCounter current_delay_counter_ RTC_GUARDED_BY(main_thread_);
+  SampleCounter oneway_delay_counter_ RTC_GUARDED_BY(main_thread_);
   std::unique_ptr<VideoQualityObserver> video_quality_observer_
       RTC_GUARDED_BY(main_thread_);
   mutable rtc::MovingMaxCounter<int> interframe_delay_max_moving_
diff --git a/video/video_quality_observer2.h b/video/video_quality_observer2.h
index 00650b5..87dff9b 100644
--- a/video/video_quality_observer2.h
+++ b/video/video_quality_observer2.h
@@ -76,10 +76,10 @@
   double sum_squared_interframe_delays_secs_;
   // An inter-frame delay is counted as a freeze if it's significantly longer
   // than average inter-frame delay.
-  rtc::SampleCounter freezes_durations_;
-  rtc::SampleCounter pauses_durations_;
+  SampleCounter freezes_durations_;
+  SampleCounter pauses_durations_;
   // Time between freezes.
-  rtc::SampleCounter smooth_playback_durations_;
+  SampleCounter smooth_playback_durations_;
   // Counters for time spent in different resolutions. Time between each two
   // Consecutive frames is counted to bin corresponding to the first frame
   // resolution.