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Ensure PDF browsing contexts have no DOM
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Previously, the spec allowed either the "page load processing model for content that uses plugins" or the "page load processing model for inline content that doesn't have a DOM" to be used for PDFs. The observable difference was that plugin documents could be same-origin to their containing page, allowing the containing page to observe the <embed> element etc.

Since Firefox manages to get away with the "no DOM" path, and that path is simpler, we make it the only allowed path.

This also fixes a few bugs in the no-DOM processing model:

* If it was reached for the PDF case, there was no check to disallow viewing the PDF in a sandboxed browsing context.
* It was passing a null request to the Document creation algorithm, which was not allowed.
* It would lose the history handling behavior, so it would not properly do replace navigations if requested.
* It would lose the navigation id, so it would not properly signal the results to WebDriver BiDi.
* It was missing a few other navigation params fields.
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@domenic
domenic committed Aug 30, 2021
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Expand Up @@ -86540,8 +86540,8 @@ interface <dfn interface>Location</dfn> { // but see also <a href="#the-location
is neither "<code data-x="javascript protocol">javascript</code>" nor a <span>fetch
scheme</span></dt>
<dd><p>Run <span>process a navigate URL scheme</span> given <var>resource</var>'s <span
data-x="concept-request-url">URL</span>, <var>browsingContext</var>, and
<var>hasTransientActivation</var>.</p></dd>
data-x="concept-request-url">URL</span>, <var>browsingContext</var>, <var>navigationId</var>,
<var>historyHandling</var>, and <var>hasTransientActivation</var>.</p></dd>
</dl>
</li>
</ol>
Expand Down Expand Up @@ -86807,7 +86807,10 @@ interface <dfn interface>Location</dfn> { // but see also <a href="#the-location

<ol>
<li><p><span>Process a navigate URL scheme</span> given <var>locationURL</var>,
<var>browsingContext</var>, and <var>hasTransientActivation</var>.</p></li>
<var>browsingContext</var>, <var>navigationParams</var>'s <span
data-x="navigation-params-id">id</span>, <var>navigationParams</var>'s <span
data-x="navigation-params-hh">history handling</span>, and
<var>hasTransientActivation</var>.</p></li>

<li><p>Return.</p></li>
</ol>
Expand Down Expand Up @@ -86891,7 +86894,9 @@ interface <dfn interface>Location</dfn> { // but see also <a href="#the-location

<ol>
<li><p><span data-x="navigate-ua-inline">Display the inline content with an appropriate error
shown to the user</span> given <var>browsingContext</var>.</p></li>
shown to the user</span> given <var>browsingContext</var>, <var>navigationParams</var>'s <span
data-x="navigation-params-id">id</span>, and <var>navigationParams</var>'s <span
data-x="navigation-params-hh">history handling</span>.</p></li>

<li><p>Run the <span data-x="environment discarding steps">environment discarding steps</span>
for <var>navigationParams</var>'s <span
Expand Down Expand Up @@ -86983,14 +86988,18 @@ interface <dfn interface>Location</dfn> { // but see also <a href="#the-location
<dt>"<code data-x="">application/pdf</code>"</dt>
<dt>"<code data-x="">text/pdf</code>"</dt>
<dd>
<p>If the user agent's <span>PDF viewer supported</span> is true, then either follow the steps
given in the <span data-x="navigate-plugin">plugin</span> section providing
<var>navigationParams</var> and <var>type</var>, or <span data-x="navigate-ua-inline">display
the inline content</span> given <var>browsingContext</var>. Once the steps have completed,
return.</p>

<p class="XXX">See <a href="https://github.com/whatwg/html/issues/6003">issue #6003</a> for
discussion on picking one of these two behaviors to standardize.</p>
<p>If <var>navigationParams</var>'s <span data-x="navigation-params-sandboxing">final
sandboxing flag set</span> does not have its <span>sandboxed plugins browsing context
flag</span> set, then <span data-x="navigate-ua-inline">display an appropriate error
message</span> given <var>browsingContext</var>, <var>navigationParams</var>'s <span
data-x="navigation-params-id">id</span>, and <var>navigationParams</var>'s <span
data-x="navigation-params-hh">history handling</span>.</p>

<p>Otherwise, if the user agent's <span>PDF viewer supported</span> is true, then <span
data-x="navigate-ua-inline">display the PDF inline in a viewer</span> given
<var>browsingContext</var>, <var>navigationParams</var>'s <span
data-x="navigation-params-id">id</span>, and <var>navigationParams</var>'s <span
data-x="navigation-params-hh">history handling</span>.</p>

<p>Otherwise, proceed onward.</p>
</dd>
Expand All @@ -87011,11 +87020,13 @@ interface <dfn interface>Location</dfn> { // but see also <a href="#the-location
the user agent has a dedicated handler.</p>
</li>

<li id="navigate-non-Document"><p>If, given <var>type</var>, the new resource is to be handled by
displaying some sort of inline content, e.g., a native rendering of the content or an error
<li id="navigate-non-Document"><p>If, given <var>type</var>, the new resource is to be handled
by displaying some sort of inline content, e.g., a native rendering of the content or an error
message because the specified type is not supported, then <span
data-x="navigate-ua-inline">display the inline content</span> given <var>browsingContext</var>,
and then return.</p></li>
data-x="navigate-ua-inline">display the inline content</span> given <var>browsingContext</var>,
<var>navigationParams</var>'s <span data-x="navigation-params-id">id</span>, and
<var>navigationParams</var>'s <span data-x="navigation-params-hh">history handling</span>, and
then return.</p></li>

<li><p>Otherwise, the document's <var>type</var> is such that the resource will not affect
<var>browsingContext</var>, e.g., because the resource is to be handed to an external application
Expand All @@ -87028,8 +87039,9 @@ interface <dfn interface>Location</dfn> { // but see also <a href="#the-location
</ol>

<p>To <dfn>process a navigate URL scheme</dfn>, given a <span>URL</span> <var>url</var>, a
<span>browsing context</span> <var>browsingContext</var>, and a boolean
<var>hasTransientActivation</var>:</p>
<span>browsing context</span> <var>browsingContext</var>, a <span
data-x="navigation-id">navigation id</span> <var>navigationId</var>, a <span>history handling
behavior</span> <var>historyHandling</var>, and a boolean <var>hasTransientActivation</var>:</p>

<ol>
<li><p>If <var>url</var> is to be handled using a mechanism that does not affect
Expand All @@ -87042,7 +87054,8 @@ interface <dfn interface>Location</dfn> { // but see also <a href="#the-location
an error message because the specified scheme is not one of the supported protocols, or an
inline prompt to allow the user to select <span data-x="dom-navigator-registerProtocolHandler">a
registered handler</span> for the given scheme. <span data-x="navigate-ua-inline">Display the
inline content</span> given <var>browsingContext</var>.</p>
inline content</span> given <var>browsingContext</var>, <var>navigationId</var>, and
<var>historyHandling</var>.</p>

<p class="note">In the case of a registered handler being used, <span>navigate</span> will be
invoked with a new URL.</p>
Expand Down Expand Up @@ -87810,97 +87823,54 @@ new PaymentRequest(&hellip;); // Allowed to use
data-x="attr-media-autoplay">autoplay</span>.</p>


<h4 id="read-plugin"><dfn data-x="navigate-plugin">Page load processing model for content that uses plugins</dfn></h4>
<h4 id="read-ua-inline"><span id="read-ua-plugin"></span><span id="navigate-plugin"></span><dfn
data-x="navigate-ua-inline">Page load processing model for inline content that doesn't have a
DOM</dfn></h4>

<p>When a resource that requires an external resource to be rendered is to be loaded, provided
<span>navigation params</span> <var>navigationParams</var> and a string <var>type</var>, the user
agent should:
<p>When the user agent is to display a user agent page or PDF viewer inline, provided a
<span>browsing context</span> <var>browsingContext</var>, a <span
data-x="navigation-id">navigation id</span> <var>navigationId</var>, and a <span>history handling
behavior</span> <var>historyHandling</var>, the user agent should:</p>

<ol>
<li><p>Let <var>document</var> be the result of <span
data-x="create-the-document-object">creating and initializing a <code>Document</code>
object</span> given "<code data-x="">html</code>", <var>type</var>, and
<var>navigationParmas</var>.</p></li>

<li><p>Set <var>document</var>'s <span data-x="concept-document-mode">mode</span>
to "<code data-x="">no-quirks</code>".</p></li>

<li><p>Mark <var>document</var> as being a <dfn>plugin document</dfn></p></li>

<li><p>Append an <code>html</code> element to <var>document</var>.</p></li>

<li><p>Append a <code>head</code> element to the <code>html</code> element.</p></li>

<li><p>Append a <code>body</code> element to the <code>html</code> element.</p></li>

<li><p>Append an <code>embed</code> to the <code>body</code> element.</p></li>

<li><p>Set the <code data-x="attr-embed-src">src</code> attribute of the <code>embed</code>
element to the address of the resource.</p></li>
</ol>

<p class="note">The term <span>plugin document</span> is used by
<cite>Content Security Policy</cite> as part of the mechanism that ensures <code>iframe</code>s
can't be used to evade <code data-x="">plugin-types</code> directives. <ref spec=CSP></p>

<!-- next three paragraphs are similar to the navigate-text section, keep them in sync -->

<p>Then, the user agent must act as if it had <span data-x="stop parsing">stopped
parsing</span>.</p>

<p>After creating the <code>Document</code> object, but potentially before the page has finished
fully loading, the user agent must <span>update the session history with the new page</span> given
<var>navigationParams</var> and the newly-created <code>Document</code>.</p>

<p>User agents may add content to the <code>head</code> element of the <code>Document</code>, or
attributes to the <code>embed</code> element, e.g. to link to a style sheet or to give the
document a <code>title</code>.</p>

<p class="note" id="sandboxPluginNavigate">If the <code>Document</code>'s <span>active sandboxing
flag set</span> has its <span>sandboxed plugins browsing context flag</span> set, the synthesized
<code>embed</code> element will <a href="#sandboxPluginEmbed">fail to render the content</a>.</p>


<h4 id="read-ua-inline"><dfn data-x="navigate-ua-inline">Page load processing model for inline
content that doesn't have a DOM</dfn></h4>

<p>When the user agent is to display a user agent page inline, provided a <span>browsing
context</span> <var>browsingContext</var>, the user agent should:</p>

<ol>
<li>
<p>Let <var>navigationParams</var> be a new <span>navigation params</span> whose <span
data-x="navigation-params-request">request</span> is null, <span
data-x="navigation-params-response">response</span> is null, <span
data-x="navigation-params-origin">origin</span> is a new <span
data-x="concept-origin-opaque">opaque origin</span>, <span
data-x="navigation-params-sandboxing">final sandboxing flag set</span> is an empty set, <span
data-x="navigation-params-coop">cross-origin opener policy</span> is a new <span>cross-origin
opener policy</span>, <span data-x="navigation-params-coop-enforcement-result">COOP enforcement
result</span> is a new <span data-x="coop-enforcement-result">cross-origin opener policy
enforcement result</span>, <span
data-x="navigation-params-reserved-environment">reserved environment</span> is null, and <span
data-x="navigation-params-browsing-context">browsing context</span> is
<var>browsingContext</var>.</p>

<p class="XXX">The algorithm called in the next step is not prepared to deal with a null <span
data-x="navigation-params-response">response</span>. Probably we should synthesize one
instead.</p>
</li>
<li><p>Let <var>navigationParams</var> be a new <span>navigation params</span> whose <span
data-x="navigation-params-id">id</span> is <var>navigationId</var>, <span
data-x="navigation-params-request">request</span> is null, <span
data-x="navigation-params-response">response</span> is a new <span
data-x="concept-response">response</span>, <span data-x="navigation-params-origin">origin</span>
is a new <span data-x="concept-origin-opaque">opaque origin</span>, <span
data-x="navigation-params-policy-container">policy container</span> is a new <span>policy
container</span>, <span data-x="navigation-params-sandboxing">final sandboxing flag set</span>
is an empty set, <span data-x="navigation-params-coop">cross-origin opener policy</span> is a
new <span>cross-origin opener policy</span>, <span
data-x="navigation-params-coop-enforcement-result">COOP enforcement result</span> is a new <span
data-x="coop-enforcement-result">cross-origin opener policy enforcement result</span>, <span
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 data-x="navigation-params-has-cross-origin-redirects">has
cross-origin redirects</span> is false.</p></li>

<li><p>Let <var>document</var> be the result of <span
data-x="create-the-document-object">creating and initializing a <code>Document</code>
object</span> given "<code data-x="">html</code>", "<code data-x="">text/html</code>", and
<var>navigationParams</var>.</p></li>

<li><p>Set <var>document</var>'s <span data-x="concept-document-mode">mode</span>
to "<code data-x="">no-quirks</code>".</p></li>

<li><p>Either associate <var>document</var> with a custom rendering that is not rendered using
the normal <code>Document</code> rendering rules, or mutate <var>document</var> until it
represents the content the user agent wants to render.</p>
</ol>

<p class="note">Because we ensure the resulting <code>Document</code>'s <span
data-x="concept-document-origin">origin</span> is <span
data-x="concept-origin-opaque">opaque</span>, and the resulting <code>Document</code> cannot run
script with access to the DOM, the existence and properties of this <code>Document</code> are not
observable to web developer code. This means that most of the above values, e.g., the
<code>text/html</code> <span data-x="concept-document-type">type</span>, do not matter.
Similarly, most of the items in <var>navigationParams</var> don't have any observable effect,
besides preventing the <span data-x="create-the-document-object"><code>Document</code>-creation
algorithm</span> from getting confused, and so are set to default values.</p>

<!-- next two paragraphs are similar to the navigate-text section, keep them in sync -->

<p>Once the page has been set up, the user agent must act as if it had <span data-x="stop
Expand Down

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