Merge "TIF: add more documentation on Hardware session." into lmp-mr1-dev

    /**

     * Base class for a TV input session which represents an external device connected to a

     * hardware TV input. Once TV input returns an implementation of this class on

     * {@link #onCreateSession(String)}, the framework will create a hardware session and forward

     * the application's surface to the hardware TV input.

     * hardware TV input.

     * <p>

     * This class is for an input which provides channels for the external set-top box to the

     * application. Once a TV input returns an implementation of this class on

     * {@link #onCreateSession(String)}, the framework will create a separate session for

     * a hardware TV Input (e.g. HDMI 1) and forward the application's surface to the session so

     * that the user can see the screen of the hardware TV Input when she tunes to a channel from

     * this TV input. The implementation of this class is expected to change the channel of the

     * external set-top box via a proprietary protocol when {@link HardwareSession#onTune(Uri)} is

     * requested by the application.

     * </p><p>

     * Note that this class is not for inputs for internal hardware like built-in tuner and HDMI 1.

     * </p>

     * @see #onCreateSession(String)

     */

    public abstract static class HardwareSession extends Session {