EME: Update MediaKeySystemConfiguration defaults; require non-empty capabilities

third_party/WebKit/public/platform/WebMediaKeySystemConfiguration.h

Index: third_party/WebKit/public/platform/WebMediaKeySystemConfiguration.h
diff --git a/third_party/WebKit/public/platform/WebMediaKeySystemConfiguration.h b/third_party/WebKit/public/platform/WebMediaKeySystemConfiguration.h
index d2a7221e930f84e0e99c8ecf85c02245bad86ae2..8b3db3bfa78321bcbf0f2e2b9559552a5f9a9371 100644
--- a/third_party/WebKit/public/platform/WebMediaKeySystemConfiguration.h
+++ b/third_party/WebKit/public/platform/WebMediaKeySystemConfiguration.h
@@ -18,23 +18,13 @@ struct WebMediaKeySystemConfiguration {
         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;