Fixes widevine metrics proto serialization

Changes to a much more efficient and more reusable protobuf format for
metrics.

Test: Widevine tests, Google Play and MediaDrm CTS test.
Bug: 73724218

Change-Id: I3299051d7a16bcd7758c8f272415ca40e10c1313

libwvdrmengine/cdm/metrics/include/distribution.h

@@ -27,23 +27,23 @@ class Distribution {
   Distribution();
 
   // Uses the provided sample value to update the computed statistics.
-  void Record(double value);
+  void Record(float value);
 
   // Return the value for each of the stats computed about the series of
   // values (min, max, count, etc.).
-  double Min() const { return min_; }
-  double Max() const { return max_; }
-  double Mean() const { return mean_; }
-  int64_t Count() const { return count_; }
+  float Min() const { return min_; }
+  float Max() const { return max_; }
+  float Mean() const { return mean_; }
+  uint64_t Count() const { return count_; }
   double Variance() const {
     return count_ == 0 ? 0.0 : sum_squared_deviation_ / count_;
   }
 
  private:
-  int64_t count_;
-  double min_;
-  double max_;
-  double mean_;
+  uint64_t count_;
+  float min_;
+  float max_;
+  float mean_;
   double sum_squared_deviation_;
 };