Add method cricket::VideoCapturer::NeedsDenoising, use in VideoCapturerTrackSource.

webrtc/media/base/videocapturer.h

Index: webrtc/media/base/videocapturer.h
diff --git a/webrtc/media/base/videocapturer.h b/webrtc/media/base/videocapturer.h
index c9c96eeb1d299cb06eaad73c8d4734cfdc357eac..eb868d9877c0fc664b3f7fc0a042c154f74f90b6 100644
--- a/webrtc/media/base/videocapturer.h
+++ b/webrtc/media/base/videocapturer.h
@@ -175,6 +175,18 @@ class VideoCapturer : public sigslot::has_slots<>,
   // implement screencast specific behavior.
   virtual bool IsScreencast() const = 0;
 
+  // Indicates that the encoder should denoise video before encoding
+  // it, wired up to VideoCapturerTrackSource::needs_denoising. If it
+  // is not set, the default configuration is used which is different
+  // depending on video codec.
+  // TODO(nisse): This is a workaround needed to fix
+  // https://bugs.chromium.org/p/chromium/issues/detail?id=645907.
+  // Chrome should migrate to implement VideoTrackSourceInterface
+  // directly, and then this method is no longer needed.
+  virtual rtc::Optional<bool> NeedsDenoising() const {
+    return rtc::Optional<bool>();
+  }
+
   // Caps the VideoCapturer's format according to max_format. It can e.g. be
   // used to prevent cameras from capturing at a resolution or framerate that
   // the capturer is capable of but not performing satisfactorily at.