[EME] Check support for full content type (including codecs)

https://bugs.webkit.org/show_bug.cgi?id=310709

Reviewed by NOBODY (OOPS!).

When evaluating media capabilities for requestMediaKeySystemAccess,
we use pass ParsedContentType's m_mimeType to the MediaSource,
which omits parameters of the MIME type like codecs.

The right field to use here is m_contentType, so MediaSource
can check support against the full MIME type, rather than just
its container type.

* Source/WebCore/platform/encryptedmedia/CDMPrivate.cpp:
(WebCore::CDMPrivate::getSupportedCapabilitiesForAudioVideoType):
* Source/WebCore/platform/network/ParsedContentType.h:
(WebCore::ParsedContentType::contentType const): Added, returns m_contentType.

Original author: Andrzej Surdej <Andrzej_Surdej@comcast.com>
See: WebPlatformForEmbedded/WPEWebKit#1643

Author: vivienne-w

Source/WebCore/platform/encryptedmedia/CDMPrivate.cpp

@@ -422,7 +422,7 @@ std::optional<Vector<CDMMediaCapability>> CDMPrivate::getSupportedCapabilitiesFo
         // 3.13. If the user agent and implementation definitely support playback of encrypted media data for the
         //       combination of container, media types, robustness and local accumulated configuration in combination
         //       with restrictions:
-        MediaEngineSupportParameters parameters { .type = ContentType(contentType->mimeType()) };
+        MediaEngineSupportParameters parameters { .type = ContentType(contentType->contentType()) };
         if (MediaPlayer::supportsType(parameters) == MediaPlayer::SupportsType::IsNotSupported) {
             // Try with Media Source:
             parameters.platformType = PlatformMediaDecodingType::MediaSource;

Source/WebCore/platform/network/ParsedContentType.h

@@ -44,6 +44,7 @@ class ParsedContentType {
     ParsedContentType(ParsedContentType&&) = default;
 
     String mimeType() const { return m_mimeType; }
+    String contentType() const { return m_contentType; }
     String charset() const;
     void setCharset(String&&);