Reland "DL: Fix flaky getFullAXTree & wrongly updated accessibility tests"

This is a reland of 2000b5b1

Got reverted because of MSAN failure didn't run the msan bot one last time before
submitting yesterday after I changed some things to use skip-viewport-activation, oops.
The MSAN failure is because we never initialize the enum ax::mojom::NameFrom  in
InspectorAccessibilityAgent::FillCoreProperties when the ax object is a display:none node
within a locked subtree, so I set a default value for it, and it doesn't fail now!

Original change's description:
> DL: Fix flaky getFullAXTree & wrongly updated accessibility tests
>
> A devtoools display locking a11y test was marked as failing in MSAN bots
> and is also flaky when tested locally, this CL updates that test and
> fixes the cause of the failure (getFullAXTree might be called when
> style/layout is dirty, which caused failing DCHECKs).
>
> Some other display locking a11y tests were not updated correctly, and is
> updated in this CL as well.
>
> Bug: 996625
> Change-Id: I32eac1385c54eb07b1e6dab800620a2485158437
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1846618
> Commit-Queue: Rakina Zata Amni <rakina@chromium.org>
> Reviewed-by: vmpstr <vmpstr@chromium.org>
> Reviewed-by: Alice Boxhall <aboxhall@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#706834}

Bug: 996625
Change-Id: I168e40614ab600d1bd11f5cf97c166fa95400213
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1866338Reviewed-by: Alice Boxhall <aboxhall@chromium.org>
Reviewed-by: vmpstr <vmpstr@chromium.org>
Commit-Queue: Rakina Zata Amni <rakina@chromium.org>
Cr-Commit-Position: refs/heads/master@{#708131}

content/test/data/accessibility/display-locking/activatable-activated.html

@@ -2,9 +2,9 @@
 @BLINK-ALLOW:offscreen
 -->
 <div>
-  <div id="locked" rendersubtree="invisible">
+  <div id="locked" rendersubtree="invisible skip-viewport-activation">
     <div>child</div>
-    <div id="nested" rendersubtree="invisible">nested locked element!</div>
+    <div id="nested" rendersubtree="invisible skip-viewport-activation">nested locked element!</div>
     <div id="nonActivatable" rendersubtree="invisible skip-activation">nested non activatable locked element</div>
   </div>
 </div>

content/test/data/accessibility/display-locking/activatable.html

@@ -2,9 +2,9 @@
 @BLINK-ALLOW:offscreen
 -->
 <div>
-  <div id="locked" rendersubtree="invisible">
+  <div id="locked" rendersubtree="invisible skip-viewport-activation">
     <div>child</div>
-    <div id="nested" rendersubtree="invisible">nested locked element!</div>
+    <div id="nested" rendersubtree="invisible skip-viewport-activation">nested locked element!</div>
     <div id="nonActivatable" rendersubtree="invisible skip-activation">nested non activatable locked element</div>
   </div>
 </div>

content/test/data/accessibility/display-locking/all-committed.html

@@ -2,9 +2,9 @@
 @BLINK-ALLOW:offscreen
 -->
 <div>
-  <div id="locked" rendersubtree="invisible skip-activation">
+  <div id="locked" rendersubtree="invisible skip-viewport-activation">
     <div>child</div>
-    <div id="nested" rendersubtree="invisible skip-activation">nested locked element!</div>
+    <div id="nested" rendersubtree="invisible skip-viewport-activation">nested locked element!</div>
     <div id="nonActivatable" rendersubtree="invisible skip-activation">nested non activatable locked element</div>
     <!--
       TODO(rakina): Make display:none, visibility:hidden, aria-hidden nodes

content/test/data/accessibility/display-locking/all.html

@@ -2,9 +2,9 @@
 @BLINK-ALLOW:offscreen
 -->
 <div>
-  <div id="locked" rendersubtree="invisible">
+  <div id="locked" rendersubtree="invisible skip-viewport-activation">
     <div>child</div>
-    <div id="nested" rendersubtree="invisible">nested locked element!</div>
+    <div id="nested" rendersubtree="invisible skip-viewport-activation">nested locked element!</div>
     <div id="nonActivatable" rendersubtree="invisible skip-activation">nested non activatable locked element</div>
     <!--
       TODO(rakina): Make display:none, visibility:hidden, aria-hidden nodes

content/test/data/accessibility/display-locking/non-activatable.html

@@ -5,6 +5,6 @@
   <div id="locked" rendersubtree="invisible skip-activation">
     <div>child</div>
     <div id="nested" rendersubtree="invisible skip-activation">nested locked element!</div>
-    <div id="activatable" rendersubtree="invisible skip-activation">non activatable locked element</div>
+    <div id="activatable" rendersubtree="invisible skip-viewport-activation">activatable locked element</div>
   </div>
 </div>

third_party/blink/renderer/modules/accessibility/ax_object.cc

@@ -1561,6 +1561,9 @@ String AXObject::GetName(ax::mojom::NameFrom& name_from,
   bool hidden_and_ignored_but_included_in_tree =
       IsHiddenForTextAlternativeCalculation() &&
       AccessibilityIsIgnoredButIncludedInTree();
+  // Initialize |name_from|, as TextAlternative() might never set it in some
+  // cases.
+  name_from = ax::mojom::NameFrom::kNone;
   String text = TextAlternative(false, hidden_and_ignored_but_included_in_tree,
                                 visited, name_from, &related_objects, nullptr);
 

third_party/blink/renderer/modules/accessibility/inspector_accessibility_agent.cc

@@ -724,6 +724,8 @@ Response InspectorAccessibilityAgent::getFullAXTree(
   Document* document = inspected_frames_->Root()->GetDocument();
   if (!document)
     return Response::Error("No document.");
+  if (document->View()->NeedsLayout() || document->NeedsLayoutTreeUpdate())
+    document->UpdateStyleAndLayout();
   *nodes = std::make_unique<protocol::Array<protocol::Accessibility::AXNode>>();
   AXContext ax_context(*document);
   AXObjectCacheImpl& cache = ToAXObjectCacheImpl(ax_context.GetAXObjectCache());

third_party/blink/web_tests/TestExpectations

@@ -260,9 +260,6 @@ crbug.com/1004650 http/tests/security/contentSecurityPolicy/frame-src-cross-orig
 
 # Display locking failures
 
-# MSAN failure
-crbug.com/996625 inspector-protocol/accessibility/accessibility-getFullAXTree-display-locked.js [ Skip ]
-
 crbug.com/849459 fragmentation/repeating-thead-under-repeating-thead.html [ Failure ]
 
 # These tests are no longer applicable in BlinkGenPropertyTree mode.

third_party/blink/web_tests/inspector-protocol/accessibility/accessibility-getFullAXTree-display-locked.js

 (async function(testRunner) {
   var {page, session, dp} = await testRunner.startHTML(`
-    <div id='activatable' rendersubtree='invisible-activatable'>
+    <div id='activatable' rendersubtree='invisible skip-viewport-activation'>
       locked
       <div id='child'>
         child
         <div id='grandChild'>grandChild</div>
       </div>
       <div id='invisible' style='display:none'>invisible</div>
-      <div id='nested' rendersubtree='invisible-activatable'>nested</div>
+      <div id='nested' rendersubtree='invisible skip-viewport-activation'>nested</div>
       text
     </div>
-    <div id='nonActivatable' rendersubtree='invisible'>nonActivatable text</div>
+    <div id='nonActivatable' rendersubtree='invisible skip-activation'>nonActivatable text</div>
     <div id='normal'>normal text</div>
-    <script>
-      activatable.getBoundingClientRect(); // Force layout
-    </script>
   `, 'Tests accessibility values of display locked nodes');
   const dumpAccessibilityNodesFromList =
       (await testRunner.loadScript('../resources/accessibility-dumpAccessibilityNodesFromList.js'))(testRunner, session);