Merge "docs: Updating PIP N preview docs for DP2" into mnc-mr-docs

<h2 id="pip_button">Switching Your Activity to Picture-in-picture</h2>

When you need to switch your activity into PIP mode, call

<code>Activity.enterPictureInPicture()</code>. The following example switches

to PIP mode when the user selects a dedicated PIP button on a media control

bar:</p>

<code>Activity.enterPictureInPictureMode()</code>. The following example

switches to PIP mode when the user selects a dedicated PIP button on a media

control bar:</p>

<pre>

@Override

public void onActionClicked(Action action) {

    if (action.getId() == R.id.lb_control_picture_in_picture) {

        getActivity().enterPictureInPicture();

        getActivity().enterPictureInPictureMode();

        return;

    }

    ...

<p>When your activity enters PIP mode, your activity should only show video

playback. Remove UI elements before your activity enters PIP,

and restore these elements when your activity becomes full-screen again.

Override <code>Activity.onPictureInPictureChanged()</code> or

<code>Fragment.onPictureInPictureChanged()</code> and enable or

Override <code>Activity.onPictureInPictureModeChanged()</code> or

<code>Fragment.onPictureInPictureModeChanged()</code> and enable or

disable your UI elements as needed, for example:</p>

<pre>

@Override

public void onPictureInPictureChanged(boolean inPictureInPicture) {

    if (inPictureInPicture) {

public void onPictureInPictureModeChanged(boolean isInPictureInPictureMode) {

    if (isInPictureInPictureMode) {

        // Hide the controls in picture-in-picture mode.

        ...

    } else {

<pre>

@Override

public void onPause() {

    // If called due to PIP, do not pause playback

    if (inPictureInPicture()) {

    // If called while in PIP mode, do not pause playback

    if (isInPictureInPictureMode()) {

        // Continue playback

        ...

    }