Add content public APIs for Presentation API.

content/public/browser/presentation_screen_availability_listener.h

Index: content/public/browser/presentation_screen_availability_listener.h
diff --git a/content/public/browser/presentation_screen_availability_listener.h b/content/public/browser/presentation_screen_availability_listener.h
new file mode 100644
index 0000000000000000000000000000000000000000..4ed8749bcfe4f49b04b17b87a187d504fcfe3ec9
--- /dev/null
+++ b/content/public/browser/presentation_screen_availability_listener.h
@@ -0,0 +1,31 @@
+// Copyright 2015 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 CONTENT_PUBLIC_BROWSER_PRESENTATION_SCREEN_AVAILABILITY_LISTENER_H_
+#define CONTENT_PUBLIC_BROWSER_PRESENTATION_SCREEN_AVAILABILITY_LISTENER_H_
+
+#include <string>
+
+namespace content {
+
+// A listener interface used for receiving updates on screen availability
+// associated with a presentation URL from an embedder.
+// See also PresentationServiceDelegate.
+class PresentationScreenAvailabilityListener {
+ public:
+  // Returns the Presentation URL associated with this listener.
+  virtual std::string GetPresentationUrl() = 0;
+
+  // Called when screen availability for the associated Presentation URL has
+  // changed to |available|.
+  virtual void OnScreenAvailabilityChanged(bool available) = 0;
+
+ protected:
+  virtual ~ScreenAvailabilityListener() {}
+};
+
+}  // namespace content
+
+#endif  // CONTENT_PUBLIC_BROWSER_PRESENTATION_SCREEN_AVAILABILITY_LISTENER_H_
+