Create Pepper-based CDM for EME WD (Blink changes)

Source/modules/encryptedmedia/MediaKeysClient.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 MediaKeysClient_h
+#define MediaKeysClient_h
+
+#include "wtf/text/WTFString.h"
+
+namespace blink {
+class WebContentDecryptionModule;
+}
+
+namespace WebCore {
+
+class ExecutionContext;
+class Page;
+
+class MediaKeysClient {
+public:
+    virtual blink::WebContentDecryptionModule* createContentDecryptionModule(ExecutionContext*, const String& keySystem) = 0;
+
+protected:
+    virtual ~MediaKeysClient() { }
+};
+
+void provideMediaKeysTo(Page&, MediaKeysClient*);
+
+} // namespace WebCore
+
+#endif // MediaKeysClient_h
+