Add histogram for percentage of sent frames that are limited in resolution due to bandwidth.

webrtc/video_frame.h

Index: webrtc/video_frame.h
diff --git a/webrtc/video_frame.h b/webrtc/video_frame.h
index d70a746daeb49334193c99d522cefd275615981c..a95ab4596e507732abb5902dfc8b25e5d702f05c 100644
--- a/webrtc/video_frame.h
+++ b/webrtc/video_frame.h
@@ -181,6 +181,15 @@ class EncodedImage {
   EncodedImage(uint8_t* buffer, size_t length, size_t size)
       : _buffer(buffer), _length(length), _size(size) {}
 
+  struct AdaptReason {
+    AdaptReason()
+        : bw_available(false),
+          bw_resolutions_disabled(0) {}
+
+    bool bw_available;  // True if |bw_resolutions_disabled| is provided.
+    int bw_resolutions_disabled;  // Number of resolutions that are not sent
+                                  // due to bandwidth for this frame.
+  };
   uint32_t _encodedWidth = 0;
   uint32_t _encodedHeight = 0;
   uint32_t _timeStamp = 0;
@@ -193,6 +202,7 @@ class EncodedImage {
   size_t _length;
   size_t _size;
   bool _completeFrame = false;
+  AdaptReason adapt_reason_;
 };
 
 }  // namespace webrtc