Export symbols needed by the Chromium component build (part 7).

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: I1081af5ecf7ba55a7415e09e45357b783cf300aa
Reviewed-on: https://webrtc-review.googlesource.com/c/107708
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25358}
diff --git a/pc/webrtcsdp.h b/pc/webrtcsdp.h
index 2d842a1..f185c08 100644
--- a/pc/webrtcsdp.h
+++ b/pc/webrtcsdp.h
@@ -22,6 +22,8 @@
 
 #include <string>
 
+#include "rtc_base/system/rtc_export.h"
+
 namespace cricket {
 class Candidate;
 }  // namespace cricket
@@ -46,7 +48,8 @@
 
 // Serializes a cricket Candidate.
 // candidate - The candidate to be serialized.
-std::string SdpSerializeCandidate(const cricket::Candidate& candidate);
+RTC_EXPORT std::string SdpSerializeCandidate(
+    const cricket::Candidate& candidate);
 
 // Deserializes the passed in SDP string to a JsepSessionDescription.
 // message - SDP string to be Deserialized.
@@ -76,10 +79,10 @@
 // candidate - The cricket Candidate from the SDP string.
 // error - The detail error information when parsing fails.
 // return - true on success, false on failure.
-bool SdpDeserializeCandidate(const std::string& transport_name,
-                             const std::string& message,
-                             cricket::Candidate* candidate,
-                             SdpParseError* error);
+RTC_EXPORT bool SdpDeserializeCandidate(const std::string& transport_name,
+                                        const std::string& message,
+                                        cricket::Candidate* candidate,
+                                        SdpParseError* error);
 
 }  // namespace webrtc