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/include/wv_content_decryption_module.h

@@ -11,6 +11,7 @@
 #include "cdm_identifier.h"
 #include "file_store.h"
 #include "lock.h"
+#include "metrics_front_end.h"
 #include "timer.h"
 #include "wv_cdm_types.h"
 
@@ -155,6 +156,9 @@ class WvContentDecryptionModule : public android::RefBase, public TimerHandler {
   // This contains weak pointers to the CDM instances contained in |cdms_|.
   std::map<std::string, CdmEngine*> cdm_by_session_id_;
 
+  metrics::Report* report_root_;
+  metrics::MetricsFrontEnd* front_end_;
+
   CORE_DISALLOW_COPY_AND_ASSIGN(WvContentDecryptionModule);
 };