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

media/base/video_capture_types.cc

Index: media/base/video_capture_types.cc
diff --git a/media/base/video_capture_types.cc b/media/base/video_capture_types.cc
index 0bc6ae639511625fe34fa214aacb01fd65d860d9..ed22e7d5bf2bf816b28bd209a5cf359c0cbb3c6a 100644
--- a/media/base/video_capture_types.cc
+++ b/media/base/video_capture_types.cc
@@ -11,6 +11,33 @@
 
 namespace media {
 
+PowerLineFrequency::PowerLineFrequency() {
+  freq_ = FREQUENCY_DEFAULT;
+}
+
+PowerLineFrequency::PowerLineFrequency(int freq) {
+  freq_ =  freq;
+  check();
+}
+
+PowerLineFrequency& PowerLineFrequency::operator=(int freq) {
+  freq_ = freq;
+  check();
+  return *this;
+}
+
+bool PowerLineFrequency::valid() {
+  bool ok = freq_ == FREQUENCY_DEFAULT
+    || freq_ == FREQUENCY_50HZ
+    || freq_ == FREQUENCY_60HZ;
+  return ok;
+}
+
+void PowerLineFrequency::check() {
+  DCHECK(valid());
+}
+
+
 // This list is ordered by precedence of use.
 static VideoPixelFormat const kSupportedCapturePixelFormats[] = {
     PIXEL_FORMAT_I420,