Fix cens Mode in Android CDM

(This is a merge of go/wvgerrit/20500)

This patch removes the logic that calculates the "pattern offset" from
the Android glue layer. There is no such thing as a pattern offset, and
setting this value to anything other than zero may break cens mode on
some devices.

To reduce the risk of setting this value to anything other than zero,
the offset_blocks parameter has been removed from the pattern descriptor
in the CDM Core. It will have to remain part of OEMCrypto v11,
unfortunately, but the code to set it to zero is now centralized in
CryptoSession.

Bug: 28726863
Change-Id: I9c5bfe470fe251c7a57901dc2e998f4dab7fe7d7

libwvdrmengine/mediacrypto/include/WVCryptoPlugin.h

@@ -47,7 +47,7 @@ class WVCryptoPlugin : public android::CryptoPlugin {
   wvcdm::CdmSessionId configureTestMode(const void* data, size_t size);
   static wvcdm::CdmResponseType countEncryptedBlocksInPatternedRange(
       size_t range, size_t startingOffset, const Pattern& pattern,
-      size_t startingPatternOffset, uint64_t* result);
+      uint64_t* result);
   static void incrementIV(uint64_t increaseBy, std::vector<uint8_t>* ivPtr);
 };