Fix Crash When Renewing Licenses

The changes to support the newest EME spec did not account for an
empty init data.

(This is a merge of
https://widevine-internal-review.googlesource.com/#/c/9991/
from the Widevine CDM repo.)

Bug: 14410226
Change-Id: Ieb818751fa49e92068014d64767c563da2050431

libwvdrmengine/mediadrm/src/WVDrmPlugin.cpp

@@ -161,7 +161,8 @@ status_t WVDrmPlugin::getKeyRequest(
   }
 
   CdmInitData processedInitData;
-  if (WvContentDecryptionModule::IsCenc(cdmInitDataType) &&
+  if (initData.size() > 0 &&
+      WvContentDecryptionModule::IsCenc(cdmInitDataType) &&
       !InitDataResemblesPSSH(initData)) {
     // This data was passed in the old format, pre-unwrapped. We need to wrap
     // the init data in a new PSSH header.