[RemotePlayback] Keep track of source compatibility and reject prompt() correspondingly

third_party/WebKit/public/platform/modules/remoteplayback/WebRemotePlaybackAvailability.h

+// Copyright 2016 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 WebRemotePlaybackAvailability_h
+#define WebRemotePlaybackAvailability_h
+
+namespace blink {
+
+// Various states for the remote playback availability.
+enum class WebRemotePlaybackAvailability {
+  // The availability is unknown.
+  Unknown,
+
+  // The media source is not supported by the browser - device availability
+  // monitoring is unnecessary.
+  SourceNotSupported,
+
+  // The media source is compatible with some supported device types but
+  // no devices were found.
+  DeviceNotAvailable,
+
+  // There're available devices but the current media source is not compatible
+  // with any of those.
+  SourceNotCompatible,
+
+  // There're available remote playback devices and the media source is
+  // compatible with at least one of them.
+  DeviceAvailable
+};
+
+}  // namespace blink
+
+#endif  // WebRemotePlaybackState_h