Move kMinPixelsPerFrame constant in VideoStreamEncoder to VideoEncoder::ScalingSettings.

webrtc/api/video_codecs/video_encoder.h

Index: webrtc/api/video_codecs/video_encoder.h
diff --git a/webrtc/api/video_codecs/video_encoder.h b/webrtc/api/video_codecs/video_encoder.h
index 0f21cae13a767dd54ae5ade8c272dbf3dad89564..7a319d721635227aa502eb4141cf36dd37bd6e1b 100644
--- a/webrtc/api/video_codecs/video_encoder.h
+++ b/webrtc/api/video_codecs/video_encoder.h
@@ -75,12 +75,20 @@ class VideoEncoder {
   };
   struct ScalingSettings {
     ScalingSettings(bool on, int low, int high);
+    ScalingSettings(bool on, int low, int high, int min_pixels);
+    ScalingSettings(bool on, int min_pixels);
     explicit ScalingSettings(bool on);
     ScalingSettings(const ScalingSettings&);
     ~ScalingSettings();
 
     const bool enabled;
     const rtc::Optional<QpThresholds> thresholds;
+
+    // We will never ask for a resolution lower than this.
+    // TODO(kthelgason): Lower this limit when better testing
+    // on MediaCodec and fallback implementations are in place.
+    // See https://bugs.chromium.org/p/webrtc/issues/detail?id=7206
+    const int min_pixels_per_frame = 320 * 180;
   };
 
   static VideoCodecVP8 GetDefaultVp8Settings();