Revert "Create unique cdm engines per WVDrmPlugin instance"

This change introduced b/77618383, need to revert.

This reverts commit 58234a69f2.

Change-Id: Ie7d515bcd94f2dcee6fa9b885cd0441845c82c22

Bug: 77618383

libwvdrmengine/cdm/src/wv_content_decryption_module.cpp

@@ -24,7 +24,6 @@ Lock WvContentDecryptionModule::session_sharing_id_generation_lock_;
 WvContentDecryptionModule::WvContentDecryptionModule() {}
 
 WvContentDecryptionModule::~WvContentDecryptionModule() {
-  CloseAllCdms();
   ForceDisablePolicyTimer();
 }
 
@@ -76,6 +75,8 @@ CdmResponseType WvContentDecryptionModule::CloseSession(
     cdm_by_session_id_.erase(session_id);
   }
 
+  DisablePolicyTimer();
+
   return sts;
 }
 
@@ -329,21 +330,12 @@ bool WvContentDecryptionModule::IsValidServiceCertificate(
   return cert.has_certificate();
 }
 
-
-CdmResponseType WvContentDecryptionModule::GetMetrics(
-    const CdmIdentifier& identifier, drm_metrics::WvCdmMetrics* metrics) {
-  if (!metrics) {
-    return PARAMETER_NULL;
-  }
+void WvContentDecryptionModule::GetSerializedMetrics(
+    std::string* serialized_metrics) {
   AutoLock auto_lock(cdms_lock_);
-  auto it = cdms_.find(identifier);
-  if (it == cdms_.end()) {
-    LOGE("WVContentDecryptionModule::Close. cdm_identifier not found");
-    // TODO(blueeyes): Add a better error.
-    return UNKNOWN_ERROR;
-  }
-  it->second.cdm_engine->GetMetrics()->Serialize(metrics);
-  return NO_ERROR;
+  CloseCdmsWithoutSessions();
+  metrics_group_.SerializeToString(serialized_metrics);
+  metrics_group_.Clear();
 }
 
 WvContentDecryptionModule::CdmInfo::CdmInfo()
@@ -379,26 +371,30 @@ CdmEngine* WvContentDecryptionModule::GetCdmForSessionId(
   return it->second;
 }
 
-void WvContentDecryptionModule::CloseAllCdms() {
-  AutoLock auto_lock(cdms_lock_);
+// This method requires that the caller first acquire cdms_lock_.
+void WvContentDecryptionModule::CloseCdmsWithoutSessions() {
   for (auto it = cdms_.begin(); it != cdms_.end();) {
-    it = cdms_.erase(it);
-  }
-}
+    if (it->second.cdm_engine->SessionSize() != 0) {
+      ++it;
+    } else {
+      // Retrieve the metrics from the engine and any completed
+      // sessions. Clear the metrics from any completed sessions.
+      metrics::EngineMetrics* engine_metrics =
+          it->second.cdm_engine->GetMetrics();
+      // engine_metrics should never be null.
+      if (engine_metrics != NULL) {
+        engine_metrics->Serialize(metrics_group_.add_metrics());
+      } else {
+        // Engine metrics should never be null.
+        LOGI(
+            "WvContentDecryptionModule::CloseCdmsWithoutSessions."
+            "engine_metrics was unexpectedly NULL.");
+      }
 
-CdmResponseType WvContentDecryptionModule::CloseCdm(
-    const CdmIdentifier& cdm_identifier) {
-  AutoLock auto_lock(cdms_lock_);
-  auto it = cdms_.find(cdm_identifier);
-  if (it == cdms_.end()) {
-    LOGE("WVContentDecryptionModule::Close. cdm_identifier not found");
-    // TODO(blueeyes): Create a better error.
-    return UNKNOWN_ERROR;
+      // The CDM is no longer used for this identifier, delete it.
+      it = cdms_.erase(it);
+    }
   }
-  cdms_.erase(it);
-
-  DisablePolicyTimer();
-  return NO_ERROR;
 }
 
 void WvContentDecryptionModule::EnablePolicyTimer() {
@@ -407,16 +403,28 @@ void WvContentDecryptionModule::EnablePolicyTimer() {
     policy_timer_.Start(this, kCdmPolicyTimerDurationSeconds);
 }
 
-// This implementation assumes that the caller has already acquired the
-// cdms_lock_.
 void WvContentDecryptionModule::DisablePolicyTimer() {
+  bool cdms_is_empty = false;
+  {
+    AutoLock auto_lock(cdms_lock_);
+    CloseCdmsWithoutSessions();
+    cdms_is_empty = cdms_.empty();
+  }
+
   AutoLock auto_lock(policy_timer_lock_);
-  if (cdms_.empty() && policy_timer_.IsRunning()) {
-    policy_timer_.Stop();
+  if (cdms_is_empty) {
+    if (policy_timer_.IsRunning()) {
+      policy_timer_.Stop();
+    }
   }
 }
 
 void WvContentDecryptionModule::ForceDisablePolicyTimer() {
+  {
+    AutoLock auto_lock(cdms_lock_);
+    CloseCdmsWithoutSessions();
+  }
+
   AutoLock auto_lock(policy_timer_lock_);
   if (policy_timer_.IsRunning()) {
     policy_timer_.Stop();