Make class of static functions in rtp_to_ntp.h:

webrtc/system_wrappers/BUILD.gn

Index: webrtc/system_wrappers/BUILD.gn
diff --git a/webrtc/system_wrappers/BUILD.gn b/webrtc/system_wrappers/BUILD.gn
index 7f56fd8dcb9fb1feb6f0a617ab6cd12f2dd65cc3..745867bf912b3163532d8d327770ba393ac7d154 100644
--- a/webrtc/system_wrappers/BUILD.gn
+++ b/webrtc/system_wrappers/BUILD.gn
@@ -28,7 +28,7 @@ rtc_static_library("system_wrappers") {
     "include/logging.h",
     "include/metrics.h",
     "include/ntp_time.h",
-    "include/rtp_to_ntp.h",
+    "include/rtp_to_ntp_estimator.h",
     "include/rw_lock_wrapper.h",
     "include/sleep.h",
     "include/static_instance.h",
@@ -50,7 +50,7 @@ rtc_static_library("system_wrappers") {
     "source/event_timer_win.h",
     "source/file_impl.cc",
     "source/logging.cc",
-    "source/rtp_to_ntp.cc",
+    "source/rtp_to_ntp_estimator.cc",
     "source/rw_lock.cc",
     "source/rw_lock_posix.cc",
     "source/rw_lock_posix.h",
@@ -179,7 +179,7 @@ if (rtc_include_tests) {
       "source/metrics_default_unittest.cc",
       "source/metrics_unittest.cc",
       "source/ntp_time_unittest.cc",
-      "source/rtp_to_ntp_unittest.cc",
+      "source/rtp_to_ntp_estimator_unittest.cc",
       "source/stringize_macros_unittest.cc",
     ]
     configs += [ "//build/config/compiler:no_size_t_to_int_warning" ]