Report max interframe delay over window insdead of interframe delay sum

Maximum of interframe delay is calculated over moving window in
ReceiveStatistics proxy now and reported via GetStats. Name of a metric
is also changed.

BUG=none

Review-Url: https://codereview.webrtc.org/2995143002
Cr-Commit-Position: refs/heads/master@{#19463}
diff --git a/webrtc/rtc_base/BUILD.gn b/webrtc/rtc_base/BUILD.gn
index 60d1f57..477381a 100644
--- a/webrtc/rtc_base/BUILD.gn
+++ b/webrtc/rtc_base/BUILD.gn
@@ -135,6 +135,7 @@
     "location.cc",
     "location.h",
     "mod_ops.h",
+    "moving_max_counter.h",
     "onetimeevent.h",
     "optional.cc",
     "optional.h",
@@ -824,6 +825,7 @@
       "logging_unittest.cc",
       "md5digest_unittest.cc",
       "mod_ops_unittest.cc",
+      "moving_max_counter_unittest.cc",
       "onetimeevent_unittest.cc",
       "optional_unittest.cc",
       "pathutils_unittest.cc",