feat(DRM): add drmInfo to license requests (shaka-project#4030)

Adds drmInfo field to all LICENSE-type requests.

Based on comments here: shaka-project#4001 (comment)

externs/shaka/net.js

@@ -60,6 +60,7 @@ shaka.extern.RetryParameters;
  *   retryParameters: !shaka.extern.RetryParameters,
  *   licenseRequestType: ?string,
  *   sessionId: ?string,
+ *   drmInfo: ?shaka.extern.DrmInfo,
  *   streamDataCallback: ?function(BufferSource):!Promise
  * }}
  *
@@ -90,6 +91,9 @@ shaka.extern.RetryParameters;
  * @property {?string} sessionId
  *   If this is a LICENSE request, this field contains the session ID of the
  *   EME session that made the request.
+ * @property {?shaka.extern.DrmInfo} drmInfo
+ *   If this is a LICENSE request, this field contains the DRM info used to
+ *   initialize EME.
  * @property {?function(BufferSource):!Promise} streamDataCallback
  *   A callback function to handle the chunked data of the ReadableStream.
  * @exportDoc

lib/media/drm_engine.js

@@ -1385,6 +1385,7 @@ shaka.media.DrmEngine = class {
     request.method = 'POST';
     request.licenseRequestType = event.messageType;
     request.sessionId = session.sessionId;
+    request.drmInfo = this.currentDrmInfo_;
     // NOTE: allowCrossSiteCredentials can be set in a request filter.
 
     if (shaka.media.DrmEngine.isPlayReadyKeySystem(

lib/net/networking_engine.js

@@ -220,6 +220,7 @@ shaka.net.NetworkingEngine = class extends shaka.util.FakeEventTarget {
       retryParameters: retryParams,
       licenseRequestType: null,
       sessionId: null,
+      drmInfo: null,
       streamDataCallback: streamDataCallback,
     };
   }

test/util/cmcd_manager_unit.js

@@ -123,6 +123,7 @@ describe('CmcdManager', () => {
       retryParameters: /** @type {shaka.extern.RetryParameters} */({}),
       licenseRequestType: null,
       sessionId: null,
+      drmInfo: null,
       streamDataCallback: null,
     };