Move smoothing filter to common audio and exp_filter to base/analytics.

webrtc/BUILD.gn

Index: webrtc/BUILD.gn
diff --git a/webrtc/BUILD.gn b/webrtc/BUILD.gn
index b3532b1aaf9a3f9254b0725da837b78952bb0f95..c91792083e32c36e797a71479790d897f2eeea82 100644
--- a/webrtc/BUILD.gn
+++ b/webrtc/BUILD.gn
@@ -363,6 +363,7 @@ if (rtc_include_tests) {
     testonly = true
     sources = [
       "api/fakemetricsobserver.cc",
+      "base/analytics/exp_filter_unittest.cc",
       "base/array_view_unittest.cc",
       "base/atomicops_unittest.cc",
       "base/autodetectproxy_unittest.cc",
@@ -380,7 +381,6 @@ if (rtc_include_tests) {
       "base/criticalsection_unittest.cc",
       "base/event_tracer_unittest.cc",
       "base/event_unittest.cc",
-      "base/exp_filter_unittest.cc",
       "base/file_unittest.cc",
       "base/filerotatingstream_unittest.cc",
       "base/fileutils_unittest.cc",
@@ -508,6 +508,7 @@ if (rtc_include_tests) {
     }
 
     deps = [
+      "base:rtc_analytics",
       "base:rtc_base",
       "base:rtc_base_tests_utils",
       "base:rtc_task_queue",