Widevine Metrics System

This change is the complete Widevine metrics system. It will
measure and record runtime information about what is happening
in the CDM - such as errors and throughput.

Bug: 33745339
Bug: 26027857
Change-Id: Ic9a82074f1e2b72c72d751b235f8ae361232787d

libwvdrmengine/cdm/metrics/src/metrics_front_end.cpp

@@ -0,0 +1,31 @@
+// Copyright 2016 Google Inc. All Rights Reserved
+
+#include "metrics_front_end.h"
+
+#include <stddef.h>
+
+#include <log.h>
+
+namespace wvcdm {
+namespace metrics {
+
+MetricsFrontEnd* MetricsFrontEnd::instance_ = NULL;
+
+MetricsFrontEnd::MetricsFrontEnd(Report* root) :
+    root_(root) { }
+
+MetricNotification* MetricsFrontEnd::CreateSubscriber() {
+  return root_ == NULL ? NULL : root_->NewReport();
+}
+
+MetricsFrontEnd& MetricsFrontEnd::Instance() {
+  static MetricsFrontEnd kDummy(NULL);
+  return instance_ == NULL ? kDummy : *instance_;
+}
+
+void MetricsFrontEnd::OverrideInstance(MetricsFrontEnd* instance) {
+  instance_ = instance;
+}
+
+} // namespace metrics
+} // namespace wvcdm