Docs: Adds info about setUrgent() to Syncing Data Items.

  <li>Call <a href="{@docRoot}reference/com/google/android/gms/wearable/PutDataRequest.html#setData(byte[])">

  <code>setData()</code></a> to set the payload.

  </li>

  <li>Call <a href="{@docRoot}reference/com/google/android/gms/wearable/DataApi.html#putDataItem(com.google.android.gms.common.api.GoogleApiClient, com.google.android.gms.wearable.PutDataRequest)"><code>DataApi.putDataItem()</code></a> to request the system to create the data item.

  <li>

  If a delay in syncing would negatively impact user experience, call

  <a href="{@docRoot}reference/com/google/android/gms/wearable/PutDataRequest#setUrgent()">

  {@code setUrgent()}</a>.

  </li>

  <li>When requesting data items, the system returns objects

  that properly implement the <a href="{@docRoot}reference/com/google/android/gms/wearable/DataItem.html"><code>DataItem</code></a> interface.

  <li>Call <a href="{@docRoot}reference/com/google/android/gms/wearable/DataApi.html#putDataItem(com.google.android.gms.common.api.GoogleApiClient, com.google.android.gms.wearable.PutDataRequest)"><code>DataApi.putDataItem()</code></a> to request the system to create the data item.

  </li>

  </ol>

<p>

However, instead of working with raw bytes using <a href="{@docRoot}reference/com/google/android/gms/wearable/PutDataRequest.html#setData(byte[])"><code>setData()</code></a>,

we recommend you <a href="#SyncData">use a data map</a>, which exposes

When requesting data items, the system returns objects that properly implement the

<a href="{@docRoot}reference/com/google/android/gms/wearable/DataItem.html"><code>DataItem</code>

</a> interface. However, instead of working with raw bytes using

<a href="{@docRoot}reference/com/google/android/gms/wearable/PutDataRequest.html#setData(byte[])">

<code>setData()</code></a>, we recommend you <a href="#SyncData">use a data map</a>, which exposes

a data item in an easy-to-use {@link android.os.Bundle}-like interface.

</p>

<h2 id="SyncData">Sync Data with a Data Map</h2>

<p>

When possible, use the <a href="{@docRoot}reference/com/google/android/gms/wearable/DataMap.html"><code>DataMap</code></a> class.

When possible, use the <a href="{@docRoot}reference/com/google/android/gms/wearable/DataMap.html">

<code>DataMap</code></a> class.

This approach lets you work with data items in the form of an Android {@link android.os.Bundle},

so object serialization and de-serialization is done for you, and you can manipulate data with key-value pairs.

so the system does object serialization and deserialization for you, and you can manipulate data

with key-value pairs.

</p>

<p>To use a data map:</p>

  <li>Set any desired values for the data map using the <code>put...()</code> methods, such as

  <a href="{@docRoot}reference/com/google/android/gms/wearable/DataMap.html#putString(java.lang.String, java.lang.String)"><code>putString()</code></a>.

  </li>

   <li>

   If a delay in syncing would negatively impact user experience, call

   <a href="{@docRoot}reference/com/google/android/gms/wearable/PutDataRequest#setUrgent()">

   {@code setUrgent()}</a>.

   </li>

  <li>Call <a href="{@docRoot}reference/com/google/android/gms/wearable/PutDataMapRequest.html#asPutDataRequest()"><code>PutDataMapRequest.asPutDataRequest()</code></a>

  to obtain a <a href="{@docRoot}reference/com/google/android/gms/wearable/PutDataRequest.html"><code>PutDataRequest</code></a> object.

   </li>

  <li>Call <a href="{@docRoot}reference/com/google/android/gms/wearable/DataApi.html#putDataItem(com.google.android.gms.common.api.GoogleApiClient, com.google.android.gms.wearable.PutDataRequest)"><code>DataApi.putDataItem()</code></a> to request the system to create the data item.

  <p class="note"><b>Note:</b>

  If the handset and wearable devices are disconnected,

  the data is buffered and synced when the connection is re-established.

  </p>

Layer Calls</a>.</p>

<h3>Set DataItem priority</h3>

<p>

In <a href="https://developers.google.com/android/guides/releases">Google Play services 8.3 and later</a>,

the

<a href="{@docRoot}reference/com/google/android/gms/wearable/DataApi">{@code DataApi}</a> interface

allows urgent requests for syncing of

<a href="{@docRoot}reference/com/google/android/gms/wearable/DataItem">{@code DataItems}</a>.

Normally, the system may delay delivery of

<a href="{@docRoot}reference/com/google/android/gms/wearable/DataItem">{@code DataItems}</a>

to the Wear network in order to improve battery life

for user devices, but if a delay in syncing

<a href="{@docRoot}reference/com/google/android/gms/wearable/DataItem">{@code DataItems}</a>

would negatively impact user experience, you

can mark them as urgent. For example, in a remote control app where the user expects their actions to be

reflected immediately, you can have the system sync your

<a href="{@docRoot}reference/com/google/android/gms/wearable/DataItem">{@code DataItems}</a>

immediately by calling

<a href="{@docRoot}reference/com/google/android/gms/wearable/PutDataRequest#setUrgent()">

{@code setUrgent()}</a>.

</p>

<p>

If you do not call

<a href="{@docRoot}reference/com/google/android/gms/wearable/PutDataRequest#setUrgent()">

{@code setUrgent()}</a>, the system may delay up to 30 minutes before syncing non-urgent

<a href="{@docRoot}reference/com/google/android/gms/wearable/DataItem">{@code DataItems}</a>,

but you can usually expect the delay to be a few minutes, if at all.

The default urgency is now non-urgent, so you must use

<a href="{@docRoot}reference/com/google/android/gms/wearable/PutDataRequest#setUrgent()">

{@code setUrgent()}</a> if you wish to retain the immediate-sync behavior that

existed in previous versions of the Wear API.

</p>

<h2 id="ListenEvents">Listen for Data Item Events</h2>

<p>If one side of the data layer connection changes a data item, you probably want