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

media/base/video_capture_types.h

Index: media/base/video_capture_types.h
diff --git a/media/base/video_capture_types.h b/media/base/video_capture_types.h
index 4790ea52e1e12414226a882142495ed03c4b3eaa..ea1ba032bc5c6faa552052f0e8fdf3d7053658ca 100644
--- a/media/base/video_capture_types.h
+++ b/media/base/video_capture_types.h
@@ -55,20 +55,42 @@ enum ResolutionChangePolicy {
 // Potential values of the googPowerLineFrequency optional constraint passed to
 // getUserMedia. Note that the numeric values are currently significant, and are
 // used to map enum values to corresponding frequency values.
-// TODO(ajose): http://crbug.com/525167 Consider making this a class.
-enum class PowerLineFrequency {
-  FREQUENCY_DEFAULT = 0,
-  FREQUENCY_50HZ = 50,
-  FREQUENCY_60HZ = 60,
-  FREQUENCY_MAX = FREQUENCY_60HZ
+class MEDIA_EXPORT PowerLineFrequency {
+public:
+
+  PowerLineFrequency();
+  explicit PowerLineFrequency(int freq);
+
+  int get() const { return freq_; }
+
+  bool operator==(const PowerLineFrequency& other) const {
+    return freq_ == other.freq_;
+  }
+
+  PowerLineFrequency& operator=(int freq);
+
+  bool valid();
+
+  static const int FREQUENCY_DEFAULT = 0;
+  static const int FREQUENCY_50HZ = 50;
+  static const int FREQUENCY_60HZ = 60;
+  static const int FREQUENCY_MAX = FREQUENCY_60HZ;
+
+private:
+
+  void check();
+
+  int freq_;
+
 };
+
 // Assert that the int:frequency mapping is correct.
-static_assert(static_cast<int>(PowerLineFrequency::FREQUENCY_DEFAULT) == 0,
-              "static_cast<int>(FREQUENCY_DEFAULT) must equal 0.");
-static_assert(static_cast<int>(PowerLineFrequency::FREQUENCY_50HZ) == 50,
-              "static_cast<int>(FREQUENCY_DEFAULT) must equal 50.");
-static_assert(static_cast<int>(PowerLineFrequency::FREQUENCY_60HZ) == 60,
-              "static_cast<int>(FREQUENCY_DEFAULT) must equal 60.");
+static_assert(PowerLineFrequency::FREQUENCY_DEFAULT == 0,
+              "FREQUENCY_DEFAULT must equal 0.");
+static_assert(PowerLineFrequency::FREQUENCY_50HZ == 50,
+              "FREQUENCY_50HZ must equal 50.");
+static_assert(PowerLineFrequency::FREQUENCY_60HZ == 60,
+              "FREQUENCY_60HZ must equal 60.");
 
 // Some drivers use rational time per frame instead of float frame rate, this
 // constant k is used to convert between both: A fps -> [k/k*A] seconds/frame.