Merges to android Pi release (part: 1)

Below are a set of CLs being merged from the wv cdm repo to the android repo.

* Fix handling of OEM Cert public key.

  Author: Srujan Gaddam <srujzs@google.com>

  [ Merge of http://go/wvgerrit/27921 ]

  This is a potential fix for b/36656190. Set aside public
  key on first call to get the public key, and use it afterwards.
  This gets rid of extra calls to OEMCrypto_GetOEMPublicCertificate(),
  which has side-effect of staging the OEM private key.

  This also fixes a problem where the public cert string was
  not being trimmed to match the size returned by
  OEMCrypto_GetOEMPublicCertificate().

* Complete provisioning request/response for Provisioning 3.0

  Author: Gene Morgan <gmorgan@google.com>

  [ Merge of http://go/wvgerrit/27780 ]

  Fix bug on provisioning request path where GenerateDerivedKeys()
  was being called when preparing to generate the signature.

  Add message signature verification, and call correct OEMCrypto
  routine to rewrap the private key (OEMCrypto_RewrapDeviceRSAKey30).

* Implement Cdm::deleteAllUsageRecords()

  Author: Gene Morgan <gmorgan@google.com>

  [ Merge of http://go/wvgerrit/27780 ]

  Delete all usage records for current origin.  Removes usage
  records from file system and retains the PSTs.  The deletes
  any usage entries matching those PSTs held by OEMCrypto.

  BUG: 35319024

* Remove stringencoders library from third_party.

  Author: Jacob Trimble <modmaker@google.com>

  [ Merge of http://go/wvgerrit/27585 ]

  We have a fork of the stringencoders library that we use for base64
  encoding.  This reimplements base64 encoding to remove the extra
  dependency and to reduce the amount of code.

* Add Cdm::deleteUsageRecord() based on key_set_id.

  Author: Gene Morgan <gmorgan@google.com>

  [ Merge of http://go/wvgerrit/27605 ]

  Delete specified usage record from file system usage info and
  from OEMCrypto.

  BUG: 35319024

* Modifiable OEMCrypto

  Author: Fred Gylys-Colwell <fredgc@google.com>

  [ Merge of http://go/wvgerrit/24729 ]

  This CL adds a new variant of the OEMCrypto mock code that adjusts its
  behavior based on a configuration file.  This is intended for
  testing.

  For example, a tester can set current_hdcp to 2 in the options.txt
  file, push it to the device, and verify that a license is granted for
  HDCP 2.0.  Then the tester can edit the value of current_hdcp to 1 and
  push the file to the device.  Playback should stop because the license
  is no longer valid.

  This variant uses a real level 1 liboemcrypto.so to push data to a
  secure buffer.  That means we can test playback for a license that
  requires secure buffers on an Android device with real secure buffers.

  BUG: 35141278
  BUG: 37353534

BUG: 71650075
Test: Not currently passing. Will be addressed in a subsequent
      commit in the chain.

Change-Id: I58443c510919e992bb455192e70373490a00e2b6

libwvdrmengine/third_party/stringencoders/LICENSE

@@ -1,36 +1,22 @@
-MODP_B64 - High performance base64 encoder/decoder
-https://github.com/client9/stringencoders
+The MIT License (MIT)
 
-Copyright 2005, 2006, 2007, 2016
-Nick Galbreath -- nickg [at] client9 [dot] com
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