[ua-ch] Queue getHighEntropyValues() on a Task

Aligns the implementation with the spec.
https://github.com/WICG/ua-client-hints/issues/77 discusses which Task
type it should be queued on.

Bug: 1070934
Change-Id: I3461f7f1a2e6346717e568008b9879f20d39a82e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2166103Reviewed-by: Dave Tapuska <dtapuska@chromium.org>
Reviewed-by: Aaron Tagliaboschi <aarontag@chromium.org>
Commit-Queue: Yoav Weiss <yoavweiss@chromium.org>
Cr-Commit-Position: refs/heads/master@{#763558}

third_party/blink/renderer/core/frame/navigator_ua_data.cc

@@ -4,6 +4,7 @@
 
 #include "third_party/blink/renderer/core/frame/navigator_ua_data.h"
 
+#include "base/single_thread_task_runner.h"
 #include "third_party/blink/renderer/bindings/core/v8/script_promise_resolver.h"
 #include "third_party/blink/renderer/bindings/core/v8/v8_ua_data_values.h"
 #include "third_party/blink/renderer/core/page/page.h"
@@ -66,6 +67,8 @@ ScriptPromise NavigatorUAData::getHighEntropyValues(
     Vector<String>& hints) const {
   auto* resolver = MakeGarbageCollected<ScriptPromiseResolver>(script_state);
   ScriptPromise promise = resolver->Promise();
+  auto* executionContext =
+      ExecutionContext::From(script_state);  // GetExecutionContext();
   UADataValues* values = MakeGarbageCollected<UADataValues>();
   for (const String& hint : hints) {
     if (hint == "platform") {
@@ -80,7 +83,15 @@ ScriptPromise NavigatorUAData::getHighEntropyValues(
       values->setUaFullVersion(ua_full_version_);
     }
   }
-  resolver->Resolve(values);
+
+  DCHECK(executionContext);
+  executionContext->GetTaskRunner(TaskType::kPermission)
+      ->PostTask(
+          FROM_HERE,
+          WTF::Bind([](ScriptPromiseResolver* resolver,
+                       UADataValues* values) { resolver->Resolve(values); },
+                    WrapPersistent(resolver), WrapPersistent(values)));
+
   return promise;
 }
 

third_party/blink/web_tests/external/wpt/html/webappapis/system-state-and-capabilities/the-navigator-object/navigator_user_agent.https.html

@@ -9,6 +9,7 @@
   }, "navigator.userAgentData is exposed.");
 
   promise_test(async t => {
+    let didMicrotaskRun = false;
     const uaData = navigator.userAgentData;
     for (brandVersionPair of uaData.brands) {
       assert_equals(typeof brandVersionPair.brand, "string", "brand should be a string");
@@ -25,5 +26,12 @@
     assert_equals(highEntropyData2["platformVersion"], "", "Platform version should be an empty string");
     assert_equals(highEntropyData2["architecture"], "", "Architecture should be an empty string");
     assert_equals(highEntropyData2["model"], "", "Model should be an empty string");
+    let  finalPromise = uaData.getHighEntropyValues([]).then(() => {
+      assert_true(didMicrotaskRun, "getHighEntropyValues queued on a task");
+    });
+    await Promise.resolve().then(function() {
+      didMicrotaskRun = true;
+    });
+    return finalPromise;
   }, "navigator.userAgentData returns a UserAgentMetadata object.");
 </script>