(This is a merge of modmaker@'s change from the Widevine repo,
http://go/wvgerrit/48880)
When using pattern encryption, WVCryptoPlugin needs to increment the
IV after each subsample. It should increment it based on the number
of actually encrypted samples (i.e. ignore clear data caused by
subsamples or pattern encryption).
In the common encryption spec, section 9.6.1 states:
If the last Block pattern in a Subsample is incomplete, the partial
pattern SHALL be followed until truncated by the BytesOfProtectedData
size and any partial crypt_byte_block SHALL remain unencrypted.
This fixes the counting of encrypted blocks to account for partial
patterns. This also makes it more efficient by removing the loop.
Bug: 111001481
Test: build_and_run_all_unit_tests
Test: Widevine GTS Tests
Change-Id: Ibd2bf10f64461b9bce10ef07453096fe4a4f6376
ff7f8c00bf