Make showPicker() consume user activation

Allowing the page to call showPicker() as much as it wants without
consuming user activation may result in the user being unable to
interact with the browser UI due to popups always taking focus.

Spec issue: whatwg/html#10084

Bug: 1521345
Change-Id: If6308a67bac9050f695d18d275ea86c23ac22b0d

html/semantics/forms/the-input-element/show-picker-user-gesture.html

@@ -28,4 +28,15 @@
     input.blur();
   }, `input[type=${inputType}] showPicker() does not throw when user activation is active`);
 }
+
+for (const inputType of inputTypes) {
+  promise_test(async () => {
+    const input = document.createElement('input');
+    input.setAttribute('type', inputType);
+
+    await test_driver.bless('show picker');
+    input.showPicker();
+    assert_throws_dom('NotAllowedError', () => input.showPicker());
+  }, `input[type=${inputType}] showPicker() consumes user activation.`);
+}
 </script>

html/semantics/forms/the-select-element/show-picker-user-gesture.tentative.html

@@ -20,5 +20,8 @@
         await test_driver.bless('show picker');
         select.showPicker();
         select.blur();
+
+        assert_throws_dom('NotAllowedError', () => select.showPicker(),
+            'User activation should be consumed after calling showPicker().');
     }, `select showPicker() does not throw when user activation is active`);
-</script>
+</script>