Media Capabilities: add plumbing between Blink and media/blink/.

third_party/WebKit/public/platform/modules/media_capabilities/WebMediaDecodingAbility.h

+// Copyright 2017 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 WebMediaDecodingAbility_h
+#define WebMediaDecodingAbility_h
+
+#include "public/platform/WebCallbacks.h"
+
+namespace blink {
+
+// Represents a MediaDecodingAbility dictionary to be used outside of Blink.
+// This is set by consumers and send back to Blink.
+struct WebMediaDecodingAbility {
+  bool supported = false;
+  bool smooth = false;
+  bool powerEfficient = false;
+};
+
+using WebMediaCapabilitiesQueryCallbacks =
+    WebCallbacks<std::unique_ptr<WebMediaDecodingAbility>, void>;
+
+}  // namespace blink
+
+#endif  // WebMediaDecodingAbility_h