Change VideoSourceInterface::needs_denoising() to return rtc::Optional<bool>

webrtc/api/videocapturertracksource.h

Index: webrtc/api/videocapturertracksource.h
diff --git a/webrtc/api/videocapturertracksource.h b/webrtc/api/videocapturertracksource.h
index 9a8d05d9ed9452ac2bac356f59f1c948bccb1fbc..3673bf7fd4d99eb5a608da65c0e2fa0b02f6f4a4 100644
--- a/webrtc/api/videocapturertracksource.h
+++ b/webrtc/api/videocapturertracksource.h
@@ -54,7 +54,9 @@ class VideoCapturerTrackSource : public VideoTrackSource,
   bool is_screencast() const override {
     return video_capturer_->IsScreencast();
   }
-  bool needs_denoising() const override { return needs_denoising_; }
+  rtc::Optional<bool> needs_denoising() const override {
+    return needs_denoising_;
+  }
 
   void Stop() override;
   void Restart() override;
@@ -75,7 +77,7 @@ class VideoCapturerTrackSource : public VideoTrackSource,
   rtc::scoped_ptr<cricket::VideoCapturer> video_capturer_;
   bool started_;
   cricket::VideoFormat format_;
-  bool needs_denoising_;
+  rtc::Optional<bool> needs_denoising_;
 };
 
 }  // namespace webrtc