EME: Update MediaKeySystemConfiguration defaults; require non-empty capabilities

third_party/WebKit/public/platform/WebMediaKeySystemConfiguration.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef WebMediaKeySystemConfiguration_h
 #define WebMediaKeySystemConfiguration_h
 
 #include "public/platform/WebEncryptedMediaTypes.h"
 #include "public/platform/WebMediaKeySystemMediaCapability.h"
 #include "public/platform/WebVector.h"
 
 namespace blink {
 
 struct WebMediaKeySystemConfiguration {
     enum class Requirement {
         Required,
         Optional,
         NotAllowed,
     };
 
-    // As MediaKeySystemConfiguration is a dictionary, some members may be
-    // not-present. Because requestMediaKeySystemAccess() distinguishes empty
-    // from not-present, we require a presence flag for each member.
-    bool hasInitDataTypes = false;
     WebVector<WebEncryptedMediaInitDataType> initDataTypes;
-
-    bool hasAudioCapabilities = false;
     WebVector<WebMediaKeySystemMediaCapability> audioCapabilities;
-
-    bool hasVideoCapabilities = false;
     WebVector<WebMediaKeySystemMediaCapability> videoCapabilities;
-
-    // |distinctiveIdentifier| and |persistentState| are always present because
-    // they have default values.
     Requirement distinctiveIdentifier = Requirement::Optional;
     Requirement persistentState = Requirement::Optional;
 
+    // As |sessionTypes| is optional, we require a presence flag for it.

[foolip, 2016/09/23 08:18:39]

To be pendantic, all of the above are also optional, but they have defaults in
the IDL. This one also has a default, in prose: "If this member is not present
[WebIDL] when the dictionary is passed to requestMediaKeySystemAccess(), the
dictionary will be treated as if this member is set to [ "temporary" ]."

In other words, you should be able to handle that in the conversion to
WebMediaKeySystemConfiguration and drop hasSessionTypes here too. 

[jrummell, 2016/09/29 20:40:02]

Done.

     bool hasSessionTypes = false;
     WebVector<WebEncryptedMediaSessionType> sessionTypes;
 
     // |label| may be not-present, but we use a null string to represent that.

[foolip, 2016/09/23 08:18:39]

It now has a default.

[jrummell, 2016/09/29 20:40:02]

Done.

     WebString label;
 };
 
 } // namespace blink
 
 #endif // WebMediaKeySystemConfiguration_h