Support GetPropertyByteArray for getting metrics.

Adds support for GetPropertyByteArray to return a serialized set of metrics
to the caller. This should be the last part of the widevine plugin
changes that fix the referenced bug.  More changes are coming on the
MediaDrm side.

This is a merge of wvgerrit/28422

I intend to submit 2048751, 2048750, and 2048509 together.

Bug: 36217927
Test: Added additional unit tests for affected code.
Change-Id: I2618c2be48d7d780127e35f237e2276efd080879

libwvdrmengine/cdm/src/ami_adapter.cpp

@@ -22,10 +22,6 @@ AmiAdapter::~AmiAdapter() {
   analytics_item_.selfrecord();
 }
 
-metrics::Report* AmiAdapter::NewReport() const {
-  return new AmiAdapter(analytics_item_.getSessionID());
-}
-
 void AmiAdapter::UpdateString(const std::string& metric_id,
                               const std::string& value) {
   analytics_item_.setCString(metric_id.c_str(), value.c_str());

libwvdrmengine/cdm/src/wv_content_decryption_module.cpp

@@ -7,7 +7,7 @@
 #include "initialization_data.h"
 #include "license.h"
 #include "log.h"
-#include "metrics_front_end.h"
+#include "metrics.pb.h"
 #include "properties.h"
 #include "service_certificate.h"
 #include "wv_cdm_constants.h"
@@ -21,22 +21,10 @@ namespace wvcdm {
 
 Lock WvContentDecryptionModule::session_sharing_id_generation_lock_;
 
-WvContentDecryptionModule::WvContentDecryptionModule() {
-  // TODO (b/36497276)
-  // replace call to new AmiAdapter() and remove ami_apdater.*
-  report_root_ = NULL; // new AmiAdapter();
-  front_end_ = new metrics::MetricsFrontEnd(report_root_);
-  metrics::MetricsFrontEnd::OverrideInstance(front_end_);
-}
+WvContentDecryptionModule::WvContentDecryptionModule() {}
 
 WvContentDecryptionModule::~WvContentDecryptionModule() {
   DisablePolicyTimer(true);
-
-  metrics::MetricsFrontEnd::OverrideInstance(NULL);
-  delete front_end_;
-  delete report_root_;
-  front_end_ = NULL;
-  report_root_ = NULL;
 }
 
 bool WvContentDecryptionModule::IsSupported(const std::string& init_data_type) {
@@ -406,6 +394,25 @@ bool WvContentDecryptionModule::IsValidServiceCertificate(
          NO_ERROR;
 }
 
+void WvContentDecryptionModule::GetSerializedMetrics(
+    std::string* serialized_metrics) {
+  drm_metrics::MetricsGroup metric_group;
+  {
+    AutoLock auto_lock(cdms_lock_);
+    for (auto it = cdms_.begin(); it != cdms_.end(); it++) {
+      metrics::EngineMetrics* engine_metrics =
+          it->second.cdm_engine->GetMetrics();
+      if (engine_metrics) {
+        // Serialize the metrics from the engine and any completed sessions.
+        // Clear the metrics from any completed sessions.
+        engine_metrics->Serialize(
+            metric_group.add_metric_sub_group(), true, true);
+      }
+    }
+  }
+  metric_group.SerializeToString(serialized_metrics);
+}
+
 WvContentDecryptionModule::CdmInfo::CdmInfo()
   : cdm_engine(new CdmEngine(&file_system)) {}