Corrections for limited duration licenses

[ Merge of http://go/wvgerrit/74627 ]

Limited duration licenses (where license duration is unlimited and
playback window is set to a small value) did not work correctly when
the initial decrypt call occured before the license was received.

Bug: 109653883
Test: WV unit/integration tests
Change-Id: I0738e97db525b239455e2ac93ab0bedd6611b311

libwvdrmengine/cdm/core/src/policy_engine.cpp

@@ -231,7 +231,7 @@ void PolicyEngine::UpdateLicense(const License& license) {
   NotifyExpirationUpdate(current_time);
 }
 
-void PolicyEngine::BeginDecryption() {
+bool PolicyEngine::BeginDecryption() {
   if (playback_start_time_ == 0) {
     switch (license_state_) {
       case kLicenseStateCanPlay:
@@ -246,14 +246,17 @@ void PolicyEngine::BeginDecryption() {
           license_state_ = kLicenseStateNeedRenewal;
         }
         NotifyExpirationUpdate(playback_start_time_);
-        break;
+        return true;
       case kLicenseStateInitial:
       case kLicenseStatePending:
       case kLicenseStateExpired:
       default:
-        break;
+        return false;
     }
   }
+  else {
+    return true;
+  }
 }
 
 void PolicyEngine::DecryptionEvent() { last_playback_time_ = GetCurrentTime(); }