Revert "Reland "Export symbols needed by the Chromium component build (part 1).""

This reverts commit 588f4642d1a29f7beaf28265dbd08728191b4c52.

Reason for revert: Breaks WebRTC Chromium FYI Win Builder (dbg).
lld-link: error: undefined symbol: "__declspec(dllimport) __thiscall webrtc::Config::Config(void)" (__imp_??0Config@webrtc@@QAE@XZ)
[...]

Original change's description:
> Reland "Export symbols needed by the Chromium component build (part 1)."
> 
> This reverts commit 2ea9af227517556136fd629dd2663c0d75d77c7b.
> 
> Reason for revert: The problem will be fixed by
> https://chromium-review.googlesource.com/c/chromium/src/+/1261122.
> 
> Original change's description:
> > Revert "Export symbols needed by the Chromium component build (part 1)."
> > 
> > This reverts commit 9e24dcff167c4eb3555bf0ce6eaba090c10fbe53.
> > 
> > Reason for revert: Breaks chromium.webrtc.fyi bots.
> > 
> > Original change's description:
> > > Export symbols needed by the Chromium component build (part 1).
> > > 
> > > 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: I802abd32874d42d3aa5ecd3c8022e7cf5e043d99
> > > Reviewed-on: https://webrtc-review.googlesource.com/c/103505
> > > Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
> > > Reviewed-by: Niels Moller <nisse@webrtc.org>
> > > Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
> > > Cr-Commit-Position: refs/heads/master@{#24969}
> > 
> > TBR=mbonadei@webrtc.org,kwiberg@webrtc.org,nisse@webrtc.org
> > 
> > Change-Id: I01f6e18f0d2c0f0309cdaa6c943c3927e1f1f49f
> > No-Presubmit: true
> > No-Tree-Checks: true
> > No-Try: true
> > Bug: webrtc:9419
> > Reviewed-on: https://webrtc-review.googlesource.com/c/103720
> > Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
> > Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
> > Cr-Commit-Position: refs/heads/master@{#24974}
> 
> TBR=mbonadei@webrtc.org,kwiberg@webrtc.org,nisse@webrtc.org
> 
> Change-Id: I83bbc7f550fc23e823c4d055e0a6f60c828960dd
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Bug: webrtc:9419
> Reviewed-on: https://webrtc-review.googlesource.com/c/103740
> Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
> Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#24980}

TBR=mbonadei@webrtc.org,kwiberg@webrtc.org,nisse@webrtc.org

Change-Id: I4b7cfe492f2c8eeda5c8ac52520e0cfc95ade9b0
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: webrtc:9419
Reviewed-on: https://webrtc-review.googlesource.com/c/103801
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24983}
diff --git a/api/audio_codecs/opus/BUILD.gn b/api/audio_codecs/opus/BUILD.gn
index 9c9bf33..800abbe 100644
--- a/api/audio_codecs/opus/BUILD.gn
+++ b/api/audio_codecs/opus/BUILD.gn
@@ -44,7 +44,6 @@
     "..:audio_codecs_api",
     "../../../modules/audio_coding:webrtc_opus",
     "../../../rtc_base:rtc_base_approved",
-    "../../../rtc_base/system:rtc_export",
     "//third_party/abseil-cpp/absl/types:optional",
   ]
 }
@@ -61,7 +60,6 @@
     "../../..:webrtc_common",
     "../../../modules/audio_coding:webrtc_opus",
     "../../../rtc_base:rtc_base_approved",
-    "../../../rtc_base/system:rtc_export",
     "//third_party/abseil-cpp/absl/memory",
     "//third_party/abseil-cpp/absl/types:optional",
   ]
diff --git a/api/audio_codecs/opus/audio_decoder_opus.h b/api/audio_codecs/opus/audio_decoder_opus.h
index 0fc720b..de26026 100644
--- a/api/audio_codecs/opus/audio_decoder_opus.h
+++ b/api/audio_codecs/opus/audio_decoder_opus.h
@@ -18,7 +18,6 @@
 #include "api/audio_codecs/audio_codec_pair_id.h"
 #include "api/audio_codecs/audio_decoder.h"
 #include "api/audio_codecs/audio_format.h"
-#include "rtc_base/system/rtc_export.h"
 
 namespace webrtc {
 
@@ -26,7 +25,7 @@
 // CreateAudioDecoderFactory<...>().
 //
 // NOTE: This struct is still under development and may change without notice.
-struct RTC_EXPORT AudioDecoderOpus {
+struct AudioDecoderOpus {
   struct Config {
     int num_channels;
   };
diff --git a/api/audio_codecs/opus/audio_encoder_opus.h b/api/audio_codecs/opus/audio_encoder_opus.h
index bb4aa27..20aaaf7 100644
--- a/api/audio_codecs/opus/audio_encoder_opus.h
+++ b/api/audio_codecs/opus/audio_encoder_opus.h
@@ -19,7 +19,6 @@
 #include "api/audio_codecs/audio_encoder.h"
 #include "api/audio_codecs/audio_format.h"
 #include "api/audio_codecs/opus/audio_encoder_opus_config.h"
-#include "rtc_base/system/rtc_export.h"
 
 namespace webrtc {
 
@@ -27,7 +26,7 @@
 // CreateAudioEncoderFactory<...>().
 //
 // NOTE: This struct is still under development and may change without notice.
-struct RTC_EXPORT AudioEncoderOpus {
+struct AudioEncoderOpus {
   using Config = AudioEncoderOpusConfig;
   static absl::optional<AudioEncoderOpusConfig> SdpToConfig(
       const SdpAudioFormat& audio_format);