Revert "Remove MediaKeys.isTypeSupported()."

Source/modules/encryptedmedia/MediaKeys.cpp

Index: Source/modules/encryptedmedia/MediaKeys.cpp
diff --git a/Source/modules/encryptedmedia/MediaKeys.cpp b/Source/modules/encryptedmedia/MediaKeys.cpp
index 98ff138798a43511a12cac6f5245494f2e6ae489..aca9600d4c277b4b1d853c4c84558dbbbed07e2d 100644
--- a/Source/modules/encryptedmedia/MediaKeys.cpp
+++ b/Source/modules/encryptedmedia/MediaKeys.cpp
@@ -33,13 +33,24 @@
 #include "core/dom/ExecutionContext.h"
 #include "modules/encryptedmedia/MediaKeySession.h"
 #include "modules/encryptedmedia/SimpleContentDecryptionModuleResultPromise.h"
+#include "platform/ContentType.h"
 #include "platform/Logging.h"
+#include "platform/MIMETypeRegistry.h"
 #include "platform/Timer.h"
 #include "public/platform/WebContentDecryptionModule.h"
 #include "wtf/RefPtr.h"
 
 namespace blink {
 
+static bool isKeySystemSupportedWithContentType(const String& keySystem, const String& contentType)
+{
+    ASSERT(!keySystem.isEmpty());
+
+    ContentType type(contentType);
+    String codecs = type.parameter("codecs");
+    return MIMETypeRegistry::isSupportedEncryptedMediaMIMEType(keySystem, type.type(), codecs);
+}
+
 // A class holding a pending action.
 class MediaKeys::PendingAction : public GarbageCollectedFinalized<MediaKeys::PendingAction> {
 public:
@@ -153,6 +164,28 @@ ScriptPromise MediaKeys::setServerCertificate(ScriptState* scriptState, const DO
     return promise;
 }
 
+bool MediaKeys::isTypeSupported(const String& keySystem, const String& contentType)
+{
+    WTF_LOG(Media, "MediaKeys::isTypeSupported(%s, %s)", keySystem.ascii().data(), contentType.ascii().data());
+
+    // 1. If keySystem is an empty string, return false and abort these steps.
+    if (keySystem.isEmpty())
+        return false;
+
+    // 2. If keySystem contains an unrecognized or unsupported Key System, return false and abort
+    // these steps. Key system string comparison is case-sensitive.
+    if (!isKeySystemSupportedWithContentType(keySystem, ""))
+        return false;
+
+    // 3. If contentType is an empty string, return true and abort these steps.
+    if (contentType.isEmpty())
+        return true;
+
+    // 4. If the Key System specified by keySystem does not support decrypting the container and/or
+    // codec specified by contentType, return false and abort these steps.
+    return isKeySystemSupportedWithContentType(keySystem, contentType);
+}
+
 void MediaKeys::timerFired(Timer<MediaKeys>*)
 {
     ASSERT(m_pendingActions.size());