Video capture: Refactor GetBestMatchedFormat from Win to OS independent

media/video/capture/video_capture_types.cc

Index: media/video/capture/video_capture_types.cc
diff --git a/media/video/capture/video_capture_types.cc b/media/video/capture/video_capture_types.cc
index ce5c354e290eed22fef06f69a067b4cf2d01265c..1b1fdd54ea785e040e077d9d0dcb1ae5908adc56 100644
--- a/media/video/capture/video_capture_types.cc
+++ b/media/video/capture/video_capture_types.cc
@@ -4,6 +4,8 @@
 
 #include "media/video/capture/video_capture_types.h"
 
+#include <cmath>
+
 #include "base/logging.h"
 #include "base/strings/stringprintf.h"
 #include "media/base/limits.h"
@@ -69,4 +71,11 @@ std::string VideoCaptureFormat::PixelFormatToString(VideoPixelFormat format) {
 
 VideoCaptureParams::VideoCaptureParams()
     : resolution_change_policy(RESOLUTION_POLICY_FIXED) {}
+
+float DiffVideoCaptureFormat(const VideoCaptureFormat& lhs,
+                             const VideoCaptureFormat& rhs) {
+  return std::abs(lhs.frame_size.width() - rhs.frame_size.width()) +
+         std::abs(lhs.frame_size.height() - rhs.frame_size.height()) +
+         std::fabs(lhs.frame_rate - rhs.frame_rate);
+}
 }  // namespace media