Fix uninitialized crypto pattern

Apps built against an older API don't have the recently
added pattern field in MediaCodec.CryptoInfo which causes
the crypto pattern fields to be uninitialized.  This change
ensures the pattern is initialized in all cases.

bug: 27477422
Change-Id: I5796bf5fbca93dba5bf9a2b74c1c6638b9e90f65
diff --git a/media/jni/android_media_MediaCodec.cpp b/media/jni/android_media_MediaCodec.cpp
index 2004a3a..d6994b3 100644
--- a/media/jni/android_media_MediaCodec.cpp
+++ b/media/jni/android_media_MediaCodec.cpp
@@ -1302,7 +1302,10 @@
     jobject patternObj = env->GetObjectField(cryptoInfoObj, gFields.cryptoInfoPatternID);
 
     CryptoPlugin::Pattern pattern;
-    if (patternObj != NULL) {
+    if (patternObj == NULL) {
+        pattern.mEncryptBlocks = 0;
+        pattern.mSkipBlocks = 0;
+    } else {
         pattern.mEncryptBlocks = env->GetIntField(patternObj, gFields.patternEncryptBlocksID);
         pattern.mSkipBlocks = env->GetIntField(patternObj, gFields.patternSkipBlocksID);
     }