Use MediaDrm property to ignore installed keybox

Merge from Widevine repo of http://go/wvgerrit/135984

If the MediaDrm property string debugIgnoreKeyboxCount is set to 1,
then the keybox will be ignored on the next initialization. This will
force an OTA keybox reprovisioning.

Equivalently, a 1 may be written to the file
L1/debug_ignore_keybox_count.txt.

In order to test a failed reprovisioning step, a value of 2 may be
used.

Bug: 187646550
Merged-In: Ie7d34a8b355398855f4ec43dd95dd73c5907bdeb
Change-Id: Ie7d34a8b355398855f4ec43dd95dd73c5907bdeb

libwvdrmengine/cdm/core/include/cdm_engine.h

@@ -303,6 +303,12 @@ class CdmEngine {
 
   virtual size_t SessionSize() const { return session_map_.Size(); }
 
+  // This tells the OEMCrypto adapter to ignore the next |count| keyboxes and
+  // report that it needs provisioning instead.
+  static CdmResponseType SetDebugIgnoreKeyboxCount(uint32_t count) {
+    return CryptoSession::SetDebugIgnoreKeyboxCount(count);
+  }
+
   static CdmResponseType ParseDecryptHashString(const std::string& hash_string,
                                                 CdmSessionId* id,
                                                 uint32_t* frame_number,