Add initial bitrate and frame resolution parameters to quality scaler.

webrtc/modules/video_coding/utility/quality_scaler.cc

Index: webrtc/modules/video_coding/utility/quality_scaler.cc
diff --git a/webrtc/modules/video_coding/utility/quality_scaler.cc b/webrtc/modules/video_coding/utility/quality_scaler.cc
index 76bf9f5b0399ed0d7558eed398f6894797490672..f6da4a3a6d8104199b20a8c7ade81ee3a8ffb9b1 100644
--- a/webrtc/modules/video_coding/utility/quality_scaler.cc
+++ b/webrtc/modules/video_coding/utility/quality_scaler.cc
@@ -30,11 +30,22 @@ QualityScaler::QualityScaler()
 
 void QualityScaler::Init(int low_qp_threshold,
                          int high_qp_threshold,
-                         bool use_framerate_reduction) {
+                         bool use_framerate_reduction,
+                         int initial_bitrate_kbps,
+                         int width,
+                         int height) {
   ClearSamples();
   low_qp_threshold_ = low_qp_threshold;
   high_qp_threshold_ = high_qp_threshold;
   use_framerate_reduction_ = use_framerate_reduction;
+  if (initial_bitrate_kbps > 0 && initial_bitrate_kbps < 500) {
+    // Start scaling to roughly VGA.
+    while (width * height > 700 * 500) {
+      ++downscale_shift_;
+      width /= 2;
+      height /= 2;
+    }
+  }
   target_framerate_ = -1;
 }