Change the media::PowerLineFrequency from an enum class to a proper class

media/capture/video/linux/video_capture_device_linux.cc

Index: media/capture/video/linux/video_capture_device_linux.cc
diff --git a/media/capture/video/linux/video_capture_device_linux.cc b/media/capture/video/linux/video_capture_device_linux.cc
index f4ca749ae9b69a6961c3ab3b41b96edd9360492d..9e1e4317a2a40fe438493c7e4b27aab9e098fe69 100644
--- a/media/capture/video/linux/video_capture_device_linux.cc
+++ b/media/capture/video/linux/video_capture_device_linux.cc
@@ -132,11 +132,12 @@ void VideoCaptureDeviceLinux::SetRotation(int rotation) {
 }
 
 // static
-int VideoCaptureDeviceLinux::TranslatePowerLineFrequencyToV4L2(int frequency) {
-  switch (frequency) {
-    case static_cast<int>(media::PowerLineFrequency::FREQUENCY_50HZ):
+int VideoCaptureDeviceLinux::TranslatePowerLineFrequencyToV4L2(
+  media::PowerLineFrequency frequency) {
+  switch (frequency.get()) {
+    case media::PowerLineFrequency::FREQUENCY_50HZ:
       return V4L2_CID_POWER_LINE_FREQUENCY_50HZ;
-    case static_cast<int>(media::PowerLineFrequency::FREQUENCY_60HZ):
+    case media::PowerLineFrequency::FREQUENCY_60HZ:
       return V4L2_CID_POWER_LINE_FREQUENCY_60HZ;
     default:
       // If we have no idea of the frequency, at least try and set it to AUTO.