<li>Added the [=geolocation task source=], which handles dispatching

position updates and errors.

</li>

optionally (and only if |repeats| is true) a |previousId:long|.

<li>If |previousId| was provided, let |watchId:long| be |previousId|;

Otherwise, let |watchId:long| be an [=implementation-defined=]

{{long}} that is greater than or equal to zero.

<li>[=Set/Append=] |watchId| to |watchTasks|.

<li>Let |global| be [=this=]'s [=relevant global object=].

<li>[=Queue a global task=] using the [=geolocation task source=]

with |global| to run the following steps [=in parallel=]:

<li>Do security check.

<li>If the <a>environment settings object</a> is a

<a data-cite="secure-contexts">non-secure context</a>, then:

<li>[=Call back with error=] |errorCallback| and

{{GeolocationPositionError/PERMISSION_DENIED}}.

<li>[=List/Remove=] |watchId| from |watchTasks|.

</li>

<li>Terminate this algorithm.

<li data-cite="page-visibility-2">Wait for document to become

visible.

<li>Let |document:Document| be the [=current settings

object=]'s [=associated Document=].

<li>If |document:Document| is [=Document/hidden=], wait for

the |document| to become [=Document/visible=].

<li data-tests=

"getCurrentPosition_permission_allow.https.html, getCurrentPosition_permission_deny.https.html">

[=Check permission=] passing |errorCallback|. If the check

returns failure:

<ol>

<li>[=List/Remove=] |watchId| from |watchTasks|.

</li>

<li>Terminate this algorithm.

</li>

</ol>

<li>

<dfn data-local-lt=

"acquiring a position|acquire a position">Acquire

position</dfn>.

<li>Let |acquisitionTime:DOMTimeStamp| be a new

{{DOMTimeStamp}} that represents now in milliseconds, using

01 January, 1970 UTC as the epoch.

</li>

<li>If |options|.{{PositionOptions/maximumAge}} is greater

than 0, and |cachedPosition| is not null:

<li>Let |cachedPosition:GeolocationPosition| be

[=this=]'s {{Geolocation/[[cachedPosition]]}}.

<li>Let |cacheTime:long| be |acquisitionTime| minus the

value of |options|.{{PositionOptions/maximumAge}} member.

<li>If |cachedPosition|'s

{{GeolocationPosition/timestamp}}'s value is greater than

|cacheTime|, and

|cachedPosition|.{{GeolocationPosition/[[isHighAccuracy]]}}

equals |options|.{{PositionOptions/enableHighAccuracy}}:

<ol>

<li>[=Queue a task=] on the [=geolocation task

source=] with a step that [=invokes=]

|successCallback| with |cachedPosition|.

</li>

<li>Go to <a href="#check-repeats">determine

repetition</a> steps below.

</li>

</ol>

<li>Let |timeout:Task| be a new timed [=task=] that runs in

|options|.{{PositionOptions/timeout}} milliseconds after

|acquisitionTime|, which performs the following sub-steps:

<aside class="note" title="Immediate cancellation">

<p>

An |options|.{{PositionOptions/timeout}} value 0

effectively runs the |timeout| task immediately.

</p>

</aside>

<li>If the entry for |timerId| in the [=list of active

timers=] has been cleared, then abort these steps.

</li>

<li>[=Call back with error=] with |errorCallback| and

{{GeolocationPositionError/TIMEOUT}}.

<li>Let |timerId:long| be an [=implementation-defined=]

identifier that represents |timeout|.

</li>

<li>Add |timerId| to the [=list of active timers=].

</li>

<li>Try to acquire the device's position, optionally taking

into consideration the value of

|options|.{{PositionOptions/enableHighAccuracy}}:

<ol>

<li>If acquiring a position succeeds:

<ol>

<li>Let |position:GeolocationPosition| be [=a new

`GeolocationPosition`=] passing |acquisitionTime| and

|options|.{{PositionOptions/enableHighAccuracy}}.

</li>

<li>Set [=this=]'s {{Geolocation/[[cachedPosition]]}}

to |position|.

</li>

<li>[=Queue a task=] on the [=geolocation task

source=] with a step that [=invokes=]

|successCallback| with |position|.

</li>

</ol>

</li>

<li>If acquiring a position fails:

<ol>

<li>[=Call back with error=] passing |errorCallback|

and

{{GeolocationPositionError/POSITION_UNAVAILABLE}}.

</li>

</ol>

</li>

</ol>

</li>

<li>Clear |timerId| from the [=list of active timers=].

</li>

<li>

<span id="check-repeats">Determine repetition</span>.

<li>If |repeats| is false:

<ol>

<li>[=List/Remove=] |watchId| from |watchTasks|.

</li>

<li>Terminate this algorithm.

</li>

</ol>

</ol>

</li>

<li>Wait for a significant change of geographic position. What

constitutes a significant change of geographic position is left

to the implementation. User agents MAY impose a rate limit on

the frequency position changes.

</li>

<li>If |watchTasks| [=list/contain|contains=] |watchId|, then:

<ol>

<li>[=Request position=] passing |successCallback|,

|errorCallback|, |options|, |repeats|, and |watchId|.

<li>Return |watchId|.

<li>[=Queue a task=] on the [=geolocation task source=] with a step

that [=invokes=] |callback| with |error|.

<section>

<h2>

Task sources

</h2>

<p>

The following [=task source=] is defined by this specifications.

</p>

<dl>

<dt>

The <dfn>geolocation task source</dfn>

</dt>

<dd>

Used by this specification to queue up non-blocking

{{PositionCallback}} and {{PositionErrorCallback}} when performing

[=request position|position requests=].

</dd>

</dl>

</section>