…ccount

Main changes:

- Prose similar to that used in the Web Bluetooth spec used for the garbage
collection note for the "presentation display availability" to clarify the
intent. We may want to adjust this text in #391.
- Notion of "presentation availability promise" dropped. That promise is now
referenced in `getAvailability` as "an unsettled Promise from a previous call
to `getAvailability` on `presentationRequest`". This avoids having to be
explicit about garbage collection rules.
- Step that instructs the UA to run the monitoring algorithm no longer runs
"in parallel" (see #381)
- Note added next to that step to clarify that the monitoring algorithm needs
to run again even if it is still running
- The monitoring algorithm now starts by making a shallow copy of the "set of
presentation availability objects" which gets completed with the right tuple if
there is a pending call to `start` (note there can be at most one such pending
call per controlling browsing context)
- Steps that update the `value` property adjusted to set the value directly for
`PresentationAvailability` objects that have not yet been exposed to ECMAScript
object. This is triggered by the following (new) problem: the `getAvailibility`
promise gets resolved with a `PresentationAvailability` object as soon as the
monitoring algorithm is done running, but the monitoring algorithm "queued a
task" to update the `value` property of `PresentationAvailability` objects. The
`value` property of the returned `PresentationAvailability` object would always
have been the initial value (`false` in most cases), even if the monitoring
algorithm had found an available display. Also, we probably do not want to fire
`change` events for properties that JS code has not yet been given any chance
to read. Here as well, we may want to adjust this text in #391.
- The initial `value` of newly created `PresentationAvailability` objects is
now always `false`. There should be no need to set it to `true` given that the
monitoring algorithm refreshes that value right after that (and given the
previous fix).
- I added a note next to the monitoring algorithm to clarify that a user agent
may interrupt and re-run the algorithm to group requests, which seems like a
possible optimization.

…nt (#392)

* Issue #387: Monitoring algo now takes pending request to start into account

Main changes:

- Prose similar to that used in the Web Bluetooth spec used for the garbage
collection note for the "presentation display availability" to clarify the
intent. We may want to adjust this text in #391.
- Notion of "presentation availability promise" dropped. That promise is now
referenced in `getAvailability` as "an unsettled Promise from a previous call
to `getAvailability` on `presentationRequest`". This avoids having to be
explicit about garbage collection rules.
- Step that instructs the UA to run the monitoring algorithm no longer runs
"in parallel" (see #381)
- Note added next to that step to clarify that the monitoring algorithm needs
to run again even if it is still running
- The monitoring algorithm now starts by making a shallow copy of the "set of
presentation availability objects" which gets completed with the right tuple if
there is a pending call to `start` (note there can be at most one such pending
call per controlling browsing context)
- Steps that update the `value` property adjusted to set the value directly for
`PresentationAvailability` objects that have not yet been exposed to ECMAScript
object. This is triggered by the following (new) problem: the `getAvailibility`
promise gets resolved with a `PresentationAvailability` object as soon as the
monitoring algorithm is done running, but the monitoring algorithm "queued a
task" to update the `value` property of `PresentationAvailability` objects. The
`value` property of the returned `PresentationAvailability` object would always
have been the initial value (`false` in most cases), even if the monitoring
algorithm had found an available display. Also, we probably do not want to fire
`change` events for properties that JS code has not yet been given any chance
to read. Here as well, we may want to adjust this text in #391.
- The initial `value` of newly created `PresentationAvailability` objects is
now always `false`. There should be no need to set it to `true` given that the
monitoring algorithm refreshes that value right after that (and given the
previous fix).
- I added a note next to the monitoring algorithm to clarify that a user agent
may interrupt and re-run the algorithm to group requests, which seems like a
possible optimization.

* Issue #387: Use availabilitySet in the monitoring algorithm

The variable is obviously useless if it is not referenced. This should have
been part of previous commit.

* Issue #387: drop "exposed to JS" and allow monitoring aggregation

This commit drops the fuzzy "exposed to ECMAScript" wording in the monitoring
algorithm, and replaces it with a more common "initialized" concept. The notion
is clarified in an editorial note next to the step that uses it.

The editorial note that follows the monitoring algorithm was also complete to
mention that user agents may aggregate monitoring activities across browsing
contexts.

* Issue #387: Update notes with @mfoltzgoogle suggestions