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Specify how timeOrigin is computed
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The time origin, which is the epoch for all performance timeline APIs,
was previously defined [here](https://w3c.github.io/hr-time/#dfn-time-origin).

This PR makes its computation explicity, without changing its current
definition and behavior.

- `time origin` becomes an `environment settings object` algorithm,
  computed differently for windows vs. worker scopes

- The 4 places where this timestamp is set are creation of an
`about:blank` context, beginning of navigation, confirmation of an
unload prompt, and creating a worker.

- The timestamp is a `shared monotonic clock` value, which is defined
in HR-TIME (and internally in ECMAScript).

As part of this PR, also refactored unload prompts to return a result
rather than rely on a somewhat hand-wavy "refused to allow" property.

See w3c/hr-time#131
and w3c/navigation-timing#166
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@noamr
noamr committed Nov 15, 2021
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Original file line number Diff line number Diff line change
Expand Up @@ -3151,7 +3151,9 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute

<p><cite>High Resolution Time</cite> provides the <dfn
data-x-href="https://w3c.github.io/hr-time/#dfn-current-high-resolution-time">current high
resolution time</dfn> and the <dfn
resolution time</dfn>, the <dfn
data-x-href="https://w3c.github.io/hr-time/#dfn-shared-monotonic-clock">shared monotonic
clock</dfn>, and the <dfn
data-x-href="https://w3c.github.io/hr-time/#dom-domhighrestimestamp"><code>DOMHighResTimeStamp</code></dfn>
typedef. <ref spec=HRT></p>
</dd>
Expand Down Expand Up @@ -9605,6 +9607,9 @@ partial interface <dfn id="document" data-lt="">Document</dfn> {
data-x="struct item">items</span>:</p>

<dl>
<dt><dfn export for="document load timing info">navigation start time</dfn> (default 0)</dt>
<dd>A number</dd>

<dt><dfn export for="document load timing info">DOM interactive time</dfn> (default 0)</dt>
<dt><dfn export for="document load timing info">DOM content loaded event start time</dfn>
(default 0)</dt>
Expand Down Expand Up @@ -79426,6 +79431,10 @@ popup4.close();</code></pre></div>
<ol>
<li><p>Let <var>browsingContext</var> be a new <span>browsing context</span>.</p></li>

<li><p>Let <var>blankLoadTimingInfo</var> be a new <span>document load timing info</span> with
its <span>navigation start time</span> set to the value of the
<span>shared monotonic clock</span>.</p></li>

<li id="creator-browsing-context"><p>If <var>creator</var> is non-null, then set
<var>browsingContext</var>'s <span>creator origin</span> to return <var>creator</var>'s <span
data-x="concept-document-origin">origin</span>, <var>browsingContext</var>'s <span>creator
Expand Down Expand Up @@ -79498,7 +79507,8 @@ popup4.close();</code></pre></div>
sandboxing flag set</span> is <var>sandboxFlags</var>, <span
data-x="concept-document-permissions-policy">permissions policy</span> is
<var>permissionsPolicy</var>, <span data-x="concept-document-coop">cross-origin opener
policy</span> is <var>coop</var>,
policy</span> is <var>coop</var>, <span>load timing info</span> is
<var>blankLoadTimingInfo</var>,
<span data-x="concept-document-navigation-id">navigation id</span> is null, and which is
<span>ready for post-load tasks</span>.</p></li>

Expand Down Expand Up @@ -81638,8 +81648,8 @@ dictionary <dfn dictionary>WindowPostMessageOptions</dfn> : <span>StructuredSeri
<p>To <dfn>close a browsing context</dfn> <var>browsingContext</var>, run these steps:</p>

<ol>
<li><p><span>Prompt to unload</span> <var>browsingContext</var>'s <span>active document</span>.
If the user <span>refused to allow the document to be unloaded</span>, then return.</p></li>
<li><p>If the result of calling <span>prompt to unload</span> with <var>browsingContext</var>'s
<span>active document</span> is "<code data-x="">refuse</code>", then return.</p></li>

<li><p><span data-x="unload a document">Unload</span> <var>browsingContext</var>'s <span>active
document</span>.</p></li>
Expand Down Expand Up @@ -85306,9 +85316,9 @@ interface <dfn interface>History</dfn> {
entry</var>, then run these substeps:</p>

<ol>
<li><p><span>Prompt to unload</span> the <span>active document</span> of the <var>specified
browsing context</var>. If the user <span>refused to allow the document to be
unloaded</span>, then return.</p></li>
<li><p>If the result of calling <span>prompt to unload</span> with the
<span>active document</span> of the <var>specified browsing context</var> is
"<code data-x="">refuse</code>", then return.</p></li>

<li><p><span data-x="unload a document">Unload</span> the <span>active document</span> of the
<var>specified browsing context</var>.</p></li>
Expand Down Expand Up @@ -86677,6 +86687,9 @@ interface <dfn interface>Location</dfn> { // but see also <a href="#the-location
<dt><dfn data-x="navigation-params-has-cross-origin-redirects">has cross-origin
redirects</dfn></dt>
<dd>a boolean</dd>

<dt><dfn data-x="navigation-params-start-time">start time</dfn></dt>
<dd>a number, representing a value of the <span>shared monotonic clock</span></dd>
</dl>

<p class="note">Once a <span>navigation params</span> struct is created, this standard does not
Expand Down Expand Up @@ -86728,6 +86741,9 @@ interface <dfn interface>Location</dfn> { // but see also <a href="#the-location
<dfn data-x="navigation-navigationid"><var>navigationId</var></dfn> (default null):</p>

<ol>
<li><p>Let <var>navigationStartTime</var>be the value of the
<span>shared monotonic clock</span>.</p></li>

<li><p>If <var>resource</var> is a <span>URL</span>, then set <var>resource</var> to a new <span
data-x="concept-request">request</span> whose <span data-x="concept-request-url">URL</span> is
<var>resource</var>.</p></li>
Expand Down Expand Up @@ -86839,17 +86855,23 @@ interface <dfn interface>Location</dfn> { // but see also <a href="#the-location
later.)</p></li>

<li>
<p><span>Prompt to unload</span> the <span>active document</span> of <var>browsingContext</var>.
If the user <span>refused to allow the document to be unloaded</span>, then return a new
<span>WebDriver BiDi navigation status</span> whose <span data-x="navigation-status-id">id</span>
is <var>navigationId</var> and <span data-x="navigation-status-status">status</span> is "<code
data-x="navigation-status-canceled">canceled</code>".</p>
<p>Let <var>unloadPromptResult</var> be the result of calling
<span>prompt to unload</span> with the <span>active document</span> of
<var>browsingContext</var>.</p>

<p>If this instance of the <span data-x="navigate">navigation</span> algorithm gets canceled
while this step is running, the <span>prompt to unload</span> algorithm must nonetheless be run
to completion.</p>
</li>

<li><p>If <var>unloadPromptResult</var> is "<code data-x="">refuse</code>", then return a new
<span>WebDriver BiDi navigation status</span> whose <span data-x="navigation-status-id">id</span>
is <var>navigationId</var> and <span data-x="navigation-status-status">status</span> is
"<code data-x="navigation-status-canceled">canceled</code>".</p>

<li><p>Otherwise, if <var>unloadPromptResult</var> is "<code data-x="">confirm</code>", then set
<var>navigationStartTime</var> to the value of the <span>shared monotonic clock</span>.</p></li>

<li><p><span data-x="abort a document">Abort</span> the <span>active document</span> of
<var>browsingContext</var>.</p></li>

Expand Down Expand Up @@ -86950,7 +86972,8 @@ interface <dfn interface>Location</dfn> { // but see also <a href="#the-location
data-x="navigation-params-reserved-environment">reserved environment</span> is null, <span
data-x="navigation-params-browsing-context">browsing context</span> is
<var>browsingContext</var>, <span data-x="navigation-params-hh">history handling</span> is
<var>historyHandling</var>, and <span
<var>historyHandling</var>, <span data-x="navigation-params-start-time">start time</span> is
<var>navigationStartTime</var>, and <span
data-x="navigation-params-has-cross-origin-redirects">has cross-origin redirects</span> is
false.</p></li>

Expand Down Expand Up @@ -87740,6 +87763,10 @@ interface <dfn interface>Location</dfn> { // but see also <a href="#the-location
data-x="navigation-params-request">request</span>'s <span
data-x="concept-request-current-url">current URL</span>.</p></li>

<li><p>Let <var>previousTimeOrigin</var> be <var>browsingContext</var>'s <span>active
document</span>'s <span>relevant settings object</span>'s
<span data-x="concept-settings-object-time-origin">time origin</span>.</p></li>

<li>
<p>If <var>browsingContext</var> is <span>still on its initial <code>about:blank</code>
<code>Document</code></span>, and <var>navigationParams</var>'s <span
Expand Down Expand Up @@ -87819,6 +87846,10 @@ interface <dfn interface>Location</dfn> { // but see also <a href="#the-location
create gets a new <code>Window</code> to go along with it.</p>
</li>

<li><p>Let <var>loadTimingInfo</var> be a new <span>document load timing info</span> with its
<span>navigation start time</span> set to <var>navigationParams</var>'s
<span data-x="navigation-params-start-time">start time</span>.</p></li>

<li>
<p>Let <var>document</var> be a new <code>Document</code>, whose <span
data-x="concept-document-type">type</span> is <var>type</var>, <span
Expand All @@ -87832,7 +87863,8 @@ interface <dfn interface>Location</dfn> { // but see also <a href="#the-location
<var>navigationParams</var>'s <span data-x="navigation-params-sandboxing">final sandboxing flag
set</span>, and <span data-x="concept-document-coop">cross-origin opener policy</span> is
<var>navigationParams</var>'s <span data-x="navigation-params-coop">cross-origin opener
policy</span>, and <span data-x="concept-document-navigation-id">navigation id</span> is
policy</span>, <span>load timing info</span> is <var>loadTimingInfo</var>, and
<span data-x="concept-document-navigation-id">navigation id</span> is
<var>navigationParams</var>'s <span data-x="navigation-params-id">id</span>.</p>

<p class="note">The new <code>Window</code>'s <span
Expand Down Expand Up @@ -87876,9 +87908,6 @@ interface <dfn interface>Location</dfn> { // but see also <a href="#the-location
</ol>
</li>

<li><p>Set <var>document</var>'s <span>load timing info</span> to a new <span>document load
timing info</span>.</p></li>

<li><p>Let <var>historyHandling</var> be <var>navigationParams</var>'s
<span data-x="navigation-params-hh">history handling</span>.</p></li>

Expand Down Expand Up @@ -87911,7 +87940,7 @@ interface <dfn interface>Location</dfn> { // but see also <a href="#the-location
data-x="concept-response-timing-info">timing info</span>,
<span data-x="navigation-params-response">response</span>'s <span
data-x="concept-response-service-worker-timing-info">service worker timing info</span>,
<var>redirectCount</var>, and <var>navigationType</var>.</p></li>
<var>redirectCount</var>, <var>navigationType</var>, and <var>previousTimeOrigin</var>.</p></li>

<li>
<p>If <var>navigationParams</var>'s <span data-x="navigation-params-response">response</span>
Expand Down Expand Up @@ -89151,6 +89180,8 @@ dictionary <dfn dictionary>PageTransitionEventInit</dfn> : <span>EventInit</span
<li><p>Decrease the <span>event loop</span>'s <span>termination nesting level</span> by
1.</p></li>

<li><p>Let <var>result</var> be "<code data-x="">no-prompt</code>".

<li>
<p>If all of the following are true:</p>

Expand Down Expand Up @@ -89178,8 +89209,8 @@ dictionary <dfn dictionary>PageTransitionEventInit</dfn> : <span>EventInit</span
<p>If the user agent asks the user for confirmation, it must <span>pause</span> while waiting
for the user's response.</p>

<p>If the user did not confirm the page navigation, then the user agent <dfn>refused to allow
the document to be unloaded</dfn>.</p>
<p>If the user confirmed the page navigation, then set <var>result</var> to
"<code data-x="">confirm</code>"; otherwise return "<code data-x="">refuse</code>".</p>
</li>

<li>
Expand All @@ -89193,18 +89224,24 @@ dictionary <dfn dictionary>PageTransitionEventInit</dfn> : <span>EventInit</span
<p>For each <var>browsingContext</var> in <var>descendants</var>:</p>

<ol>
<li><p><span>Prompt to unload</span> <var>browsingContext</var>'s <span>active
document</span> with the <var>recursiveFlag</var> set.</p></li>
<li><p>Let <var>internalResult</var> be the result of calling <span>prompt to unload</span>
for <var>browsingContext</var>'s <span>active document</span> with the
<var>recursiveFlag</var> set.</p></li>

<li><p>If <var>internalResult</var> is "<code data-x="">refuse</code>", then return
<var>internalResult</var>.</p></li>

<li><p>Otherwise, if <var>internalResult</var> is "<code data-x="">confirm</code>", set
<var>result</var> to <var>internalResult</var>.</p></li>

<li><p>If the user <span>refused to allow the document to be unloaded</span>, then the user
implicitly also <span data-x="refused to allow the document to be unloaded">refused to allow
<var>document</var> to be unloaded</span>; <span>break</span>.</p></li>
</ol>
</li>
</ol>
</li>

<li><p>Decrease the <var>document</var>'s <span>unload counter</span> by 1.</p></li>

<li><p>Return <var>result</var>.</p></li>
</ol>

<p>To <dfn export data-x="unload a document" data-lt="unload a document">unload</dfn> a
Expand Down Expand Up @@ -90131,6 +90168,13 @@ interface <dfn interface>BeforeUnloadEvent</dfn> : <span>Event</span> {

<dd><p>A boolean representing whether scripts that use this <span>environment settings
object</span> are allowed to use APIs that require cross-origin isolation.</p></dd>

<dt>A <dfn data-x="concept-settings-object-time-origin" export
for="environment settings object">time origin</dfn></dt>

<dd>A number representing the <span>shared monotonic clock</span> value, which is used as a
baseline for performance timeline entries. <ref spec=HRT></dd>

</dl>

<p>An <span>environment settings object</span> also has an <dfn>outstanding rejected promises
Expand Down Expand Up @@ -102031,6 +102075,10 @@ interface <dfn interface>WorkerGlobalScope</dfn> : <span>EventTarget</span> {
data-x="concept-WorkerGlobalScope-cross-origin-isolated-capability">cross-origin isolated
capability</dfn> boolean. It is initially false.</p>

<p>A <code>WorkerGlobalScope</code> object has an associated <dfn export for="WorkerGlobalScope"
data-x="concept-WorkerGlobalScope-creation-time">creation time</dfn> number. It is initially
zero.</p>

</div>

<dl class="domintro">
Expand Down Expand Up @@ -102349,13 +102397,12 @@ interface <dfn interface>SharedWorkerGlobalScope</dfn> : <span>WorkerGlobalScope
nested dedicated worker), then set <var>parent worker global scope</var> to
<var>owner</var>.</p></li>

<li>
<p>Let <var>agent</var> be the result of <span data-x="obtain a dedicated/shared worker
agent">obtaining a dedicated/shared worker agent</span> given <var>outside settings</var> and
<var>is shared</var>. Run the rest of these steps in that agent.</p>
<li><p>Let <var>workerCreationTime</var> be the value of the
<span>shared monotonic clock</span>.</p></li>

<p id="worker-processing-model-top">For the purposes of timing APIs, this is the <dfn
export>official moment of creation</dfn> of the worker.</p> </li>
<li><p>Let <var>agent</var> be the result of <span data-x="obtain a dedicated/shared worker
agent">obtaining a dedicated/shared worker agent</span> given <var>outside settings</var> and
<var>is shared</var>. Run the rest of these steps in that agent.</p></li>

<li>
<p>Let <var>realm execution context</var> be the result of <span>creating a new JavaScript
Expand All @@ -102376,6 +102423,10 @@ interface <dfn interface>SharedWorkerGlobalScope</dfn> : <span>WorkerGlobalScope
<code>SharedWorkerGlobalScope</code> object created in the previous step.</p>
</li>

<li><p>Set <var>worker global scope</var>'s
<span data-x="concept-WorkerGlobalScope-creation-time">creation time</span> to
<var>workerCreationTime</var>.</p><li>

<li><p><span>Set up a worker environment settings object</span> with <var>realm execution
context</var> and <var>outside settings</var>, and let <var>inside settings</var> be the
result.</p></li>
Expand Down Expand Up @@ -102788,6 +102839,12 @@ interface <dfn interface>SharedWorkerGlobalScope</dfn> : <span>WorkerGlobalScope
<dd><p>Return <var>worker global scope</var>'s <span
data-x="concept-WorkerGlobalScope-cross-origin-isolated-capability">cross-origin isolated
capability</span>.</p></dd>

<dt>The <span data-x="concept-settings-object-time-origin">time origin</span></dt>
<dd>
<p>Return <var>worker global scope</var>'s <span
data-x="concept-WorkerGlobalScope-creation-time">creation time</span>.</p>
</dd>
</dl>
</li>

Expand Down

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