Merge "docs: Updates to Preview Notifications doc" into mnc-mr-docs

  so that the user can respond appropriately.

When the user responds via {@link android.support.v4.app.RemoteInput},

 include the text in the reply history with the {@code setRemoteInputHistory()}

 method.

 method.</p>

<img id="fig-chat-history" src=

"{@docRoot}preview/images/inline-reply-sent.png">

<img id="fig-chat-history" src="{@docRoot}preview/images/inline-reply-sent.png">

<p class="img-caption">

  <strong>Figure 3.</strong> Screenshot of chat history in the notification

  shade.

<p>

  A notification group imposes a hierarchy on the notifications comprising it.

  At the top of that hierarchy is a parent notification that displays the first

  line of the first notification in the group. The user can progressively

  At the top of that hierarchy is a parent notification that displays summary

  information for the group. The user can progressively

  expand the notification group, and the system shows more information as the

  user drills deeper. When the user expands the bundle, the system reveals the

  first line of each notification within the bundle; when the user expands one

  of those notifications, the system reveals its entire content.

  user drills deeper. When the user expands the bundle, the system reveals more

  information for all its child notifications; when the user

  expands one of those notifications, the system reveals its entire content.

</p>

<img id="fig-bundles" src="{@docRoot}preview/images/bundles.png">

 single-line text items.</p>

<h3 id ="post">Displaying bundled notifications</h3>

<p>When a group only has a single child notification, the app should in general

not post a notification group, but instead post that notification individually.

Only if it accumulates more than one child should it display the notifications

 in a group.</p>

<p>Similarly, when a user swipes away children of an expanded

notification group, the app should remove the group as soon as there is only a

single child left. It should then convert the child into a normal, single

 notification.</p>

<p>

  The app should always post a group summary, even if the group contains just a

  single child. The system will suppress the summary and directly display the

  child notification if it only contains a single notification. This ensures

  that the system can provide a consistent experience when the user swipes away

  children of a group.

</p>

<p class="note">

  <strong>Note:</strong> This version of the N Developer Preview does not yet

  suppress the summary for notification groups containing a single child. This

  functionality will be added in a later version of the N Developer Preview.

</p>

<h3>Peeking notifications</h3>