Reland "Move smoothing filter to common audio".

webrtc/base/analytics/exp_filter.h

Index: webrtc/base/analytics/exp_filter.h
diff --git a/webrtc/base/exp_filter.h b/webrtc/base/analytics/exp_filter.h
similarity index 91%
rename from webrtc/base/exp_filter.h
rename to webrtc/base/analytics/exp_filter.h
index 174159b45f8291af985cef4552a8cca02411079e..e93de48963b4e3dfa547c62b7c200eca3dd43dd8 100644
--- a/webrtc/base/exp_filter.h
+++ b/webrtc/base/analytics/exp_filter.h
@@ -8,8 +8,8 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#ifndef WEBRTC_BASE_EXP_FILTER_H_
-#define WEBRTC_BASE_EXP_FILTER_H_
+#ifndef WEBRTC_BASE_ANALYTICS_EXP_FILTER_H_
+#define WEBRTC_BASE_ANALYTICS_EXP_FILTER_H_
 
 namespace rtc {
 
@@ -46,4 +46,4 @@ class ExpFilter {
 };
 }  // namespace rtc
 
-#endif  // WEBRTC_BASE_EXP_FILTER_H_
+#endif  // WEBRTC_BASE_ANALYTICS_EXP_FILTER_H_