ContentProtection not inherited from AdaptationSet if also present in Representation

[joeyparrish]

Test vectors from https://github.com/Axinom/dash-test-vectors seem to put ContentProtection elements at both AdaptationSet and Representation levels.

Our parser treats ContentProtection inheritance like any other inheritance in the manifest. If Representation has it, it doesn't inherit it from AdaptationSet.

To support the test vectors from Axinom, our parser will have to treat ContentProtection specially.

NOTE: Because the Axinom license server requires special headers in the license request and they don't use a unique schemeIdUri in the manifest, their content will not play in the demo app even if this is fixed. The following would have to be used as the content protection callback:

  if (schemeIdUri.toLowerCase() == 'urn:uuid:edef8ba9-79d6-4ace-a3c8-27dcd51d21ed') {
    return [{
      'keySystem': 'com.widevine.alpha',
      'licenseServerUrl': 'http://drm-widevine-licensing.axtest.net/AcquireLicense',
      'licensePreProcessor': function(info) {
        info.headers['X-AxDRM-Message'] = 'eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJ2ZXJzaW9uIjoxLCJjb21fa2V5X2lkIjoiNjllNTQwODgtZTllMC00NTMwLThjMWEtMWViNmRjZDBkMTRlIiwibWVzc2FnZSI6eyJ0eXBlIjoiZW50aXRsZW1lbnRfbWVzc2FnZSIsImtleXMiOlt7ImlkIjoiNmU1YTFkMjYtMjc1Ny00N2Q3LTgwNDYtZWFhNWQxZDM0YjVhIn1dfX0.yF7PflOPv9qHnu3ZWJNZ12jgkqTabmwXbDWk_47tLNE';
      }
    }];
  }