Move event_based_exponential_moving_average.h to webrtc namespace

Bug: webrtc:42232595
Change-Id: Ic6f52f7f4ce9163e10dd85a1b09f720c64c4087b
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/378282
Commit-Queue: Evan Shrubsole <eshr@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#43977}
diff --git a/rtc_base/numerics/event_based_exponential_moving_average.cc b/rtc_base/numerics/event_based_exponential_moving_average.cc
index 048eb0d..27b2066 100644
--- a/rtc_base/numerics/event_based_exponential_moving_average.cc
+++ b/rtc_base/numerics/event_based_exponential_moving_average.cc
@@ -24,7 +24,7 @@
 
 }  // namespace
 
-namespace rtc {
+namespace webrtc {
 
 // `half_time` specifies how much weight will be given to old samples,
 // a sample gets exponentially less weight so that it's 50%
@@ -81,4 +81,4 @@
          sqrt(sample_variance_ * estimator_variance_);
 }
 
-}  // namespace rtc
+}  // namespace webrtc
diff --git a/rtc_base/numerics/event_based_exponential_moving_average.h b/rtc_base/numerics/event_based_exponential_moving_average.h
index 7055a4d..beef017 100644
--- a/rtc_base/numerics/event_based_exponential_moving_average.h
+++ b/rtc_base/numerics/event_based_exponential_moving_average.h
@@ -16,7 +16,7 @@
 #include <limits>
 #include <optional>
 
-namespace rtc {
+namespace webrtc {
 
 /**
  * This class implements exponential moving average for time series
@@ -65,6 +65,12 @@
   std::optional<int64_t> last_observation_timestamp_;
 };
 
+}  //  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::EventBasedExponentialMovingAverage;
 }  // namespace rtc
 
 #endif  // RTC_BASE_NUMERICS_EVENT_BASED_EXPONENTIAL_MOVING_AVERAGE_H_
diff --git a/rtc_base/numerics/event_based_exponential_moving_average_unittest.cc b/rtc_base/numerics/event_based_exponential_moving_average_unittest.cc
index 89d9c5f..14ef9cb 100644
--- a/rtc_base/numerics/event_based_exponential_moving_average_unittest.cc
+++ b/rtc_base/numerics/event_based_exponential_moving_average_unittest.cc
@@ -23,7 +23,7 @@
 
 }  // namespace
 
-namespace rtc {
+namespace webrtc {
 
 TEST(EventBasedExponentialMovingAverageTest, NoValue) {
   EventBasedExponentialMovingAverage average(kHalfTime);
@@ -226,4 +226,4 @@
   average.AddSample(time, value);
 }
 
-}  // namespace rtc
+}  // namespace webrtc