Add clang-tidy support for the CDM

Bug: 256230932
Change-Id: Id3fcf024cd7dcf95218876b81359d6418f5aa067

libwvdrmengine/cdm/metrics/include/value_metric.h

@@ -39,8 +39,6 @@ void SetValue(drm_metrics::ValueMetric* value_proto, const T& value);
 template <typename T>
 class ValueMetric {
  public:
-  ValueMetric() {}
-
   // Record the value of the metric.
   void Record(const T& value) {
     std::unique_lock<std::mutex> lock(mutex_);
@@ -103,7 +101,7 @@ class ValueMetric {
  private:
   enum ValueState { kNone, kHasValue, kHasError };
 
-  T value_;
+  T value_ = T();
   int error_code_ = 0;
   ValueState state_ = kNone;