Use explicit template decl/def for RTCNonStandardStatsMember.

This should fix the error raised by lld-link while testing the WebRTC
component build (see [1]).

[1] - https://ci.chromium.org/p/chromium/builders/try/win_chromium_compile_dbg_ng/436729

Bug: webrtc:9419
Change-Id: Ia239f544432c55ae69e2da474b8284143c94a003
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/159697
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29786}
diff --git a/stats/rtc_stats.cc b/stats/rtc_stats.cc
index 92f64e4..d0a8653 100644
--- a/stats/rtc_stats.cc
+++ b/stats/rtc_stats.cc
@@ -231,4 +231,33 @@
                              VectorOfStringsToString(value_),
                              VectorOfStringsToString(value_));
 
+template class RTC_EXPORT_TEMPLATE_DEFINE(RTC_EXPORT)
+    RTCNonStandardStatsMember<bool>;
+template class RTC_EXPORT_TEMPLATE_DEFINE(RTC_EXPORT)
+    RTCNonStandardStatsMember<int32_t>;
+template class RTC_EXPORT_TEMPLATE_DEFINE(RTC_EXPORT)
+    RTCNonStandardStatsMember<uint32_t>;
+template class RTC_EXPORT_TEMPLATE_DEFINE(RTC_EXPORT)
+    RTCNonStandardStatsMember<int64_t>;
+template class RTC_EXPORT_TEMPLATE_DEFINE(RTC_EXPORT)
+    RTCNonStandardStatsMember<uint64_t>;
+template class RTC_EXPORT_TEMPLATE_DEFINE(RTC_EXPORT)
+    RTCNonStandardStatsMember<double>;
+template class RTC_EXPORT_TEMPLATE_DEFINE(RTC_EXPORT)
+    RTCNonStandardStatsMember<std::string>;
+template class RTC_EXPORT_TEMPLATE_DEFINE(RTC_EXPORT)
+    RTCNonStandardStatsMember<std::vector<bool>>;
+template class RTC_EXPORT_TEMPLATE_DEFINE(RTC_EXPORT)
+    RTCNonStandardStatsMember<std::vector<int32_t>>;
+template class RTC_EXPORT_TEMPLATE_DEFINE(RTC_EXPORT)
+    RTCNonStandardStatsMember<std::vector<uint32_t>>;
+template class RTC_EXPORT_TEMPLATE_DEFINE(RTC_EXPORT)
+    RTCNonStandardStatsMember<std::vector<int64_t>>;
+template class RTC_EXPORT_TEMPLATE_DEFINE(RTC_EXPORT)
+    RTCNonStandardStatsMember<std::vector<uint64_t>>;
+template class RTC_EXPORT_TEMPLATE_DEFINE(RTC_EXPORT)
+    RTCNonStandardStatsMember<std::vector<double>>;
+template class RTC_EXPORT_TEMPLATE_DEFINE(RTC_EXPORT)
+    RTCNonStandardStatsMember<std::vector<std::string>>;
+
 }  // namespace webrtc