Corrections to support HLS

[ Merge of https://go/wvgerrit/17055 ]

There are a few bugs that need to be addressed to get HLS to work.

* Content ID in json init data is base64 encoded and needs to be decoded
  before being added to the WidevineCencHeader proto.
* Protection scheme was not set in the WidevineCencHeader proto.
* HLS initialization data should be sent as a CENC content identification
  in a license request.

b/20630275

Change-Id: Ie0ac33ac061931df6f26c0afbf3e62e5d01e5041

libwvdrmengine/cdm/core/include/initialization_data.h

@@ -36,9 +36,9 @@ class InitializationData {
   bool ExtractHlsAttributes(const std::string& attribute_list,
                             CdmHlsMethod* method, std::vector<uint8_t>* iv,
                             std::string* uri);
-  static bool ConstructWidevineInitData(const std::string& uri,
-                                 CdmInitData* output);
-
+  static bool ConstructWidevineInitData(CdmHlsMethod method,
+                                        const std::string& uri,
+                                        CdmInitData* output);
   static bool ExtractQuotedAttribute(const std::string& attribute_list,
                                      const std::string& key,
                                      std::string* value);