Export symbols needed by the Chromium component build (part 8).

This CL uses RTC_EXPORT (defined in rtc_base/system/rtc_export.h)
to mark WebRTC symbols as visible from a shared library, this doesn't
mean these symbols are part of the public API (please continue to refer
to [1] for info about what is considered public WebRTC API).

[1] - https://webrtc.googlesource.com/src/+/HEAD/native-api.md

Bug: webrtc:9419
Change-Id: Ib2c29054b2ae008f5291bd3b762a504b18534326
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/130513
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#27410}
diff --git a/api/jsep_ice_candidate.h b/api/jsep_ice_candidate.h
index 5b22454..890c486 100644
--- a/api/jsep_ice_candidate.h
+++ b/api/jsep_ice_candidate.h
@@ -21,11 +21,12 @@
 #include "api/candidate.h"
 #include "api/jsep.h"
 #include "rtc_base/constructor_magic.h"
+#include "rtc_base/system/rtc_export.h"
 
 namespace webrtc {
 
 // Implementation of IceCandidateInterface.
-class JsepIceCandidate : public IceCandidateInterface {
+class RTC_EXPORT JsepIceCandidate : public IceCandidateInterface {
  public:
   JsepIceCandidate(const std::string& sdp_mid, int sdp_mline_index);
   JsepIceCandidate(const std::string& sdp_mid,