sensors: Do nothing in Sensor.start() when the document is not fully …

…active.

When a sensor is created on e.g. an iframe that is later removed from
its parent via removeChild(), we end up in a situation where a sensor
instance did get created but which does not have a valid
ExecutionContext by the time start() is invoked.

Check for a valid ExecutionContext when start() is called and bail out
early if it is null. w3c/sensors#415 tracks
handling non-fully active documents from a spec perspective; once that
one is fixed we should probably throw an error in this case rather than
silently doing nothing.

Bug: 1289924
Change-Id: I2b033252d93347ba7c91385bdb510b69b8298aa2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3412476
Reviewed-by: Reilly Grant <[email protected]>
Commit-Queue: Raphael Kubo Da Costa <[email protected]>
Cr-Commit-Position: refs/heads/main@{#962930}
NOKEYCHECK=True
GitOrigin-RevId: b93b733b928610c36c328a4685c2129ed8a80e7b

blink/renderer/modules/sensor/sensor.cc

@@ -91,6 +91,8 @@ Sensor::Sensor(ExecutionContext* execution_context,
 Sensor::~Sensor() = default;
 
 void Sensor::start() {
+  if (!GetExecutionContext())
+    return;
   if (state_ != SensorState::kIdle)
     return;
   state_ = SensorState::kActivating;

blink/web_tests/external/wpt/generic-sensor/generic-sensor-iframe-tests.sub.js

@@ -155,4 +155,32 @@ function run_generic_sensor_iframe_tests(sensorName) {
     iframe.parentNode.removeChild(iframe);
     window.focus();
   }, `${sensorName}: losing a document's frame with an active sensor does not crash`);
+
+  sensor_test(async t => {
+    assert_implements(sensorName in self, `${sensorName} is not supported.`);
+    const iframe = document.createElement('iframe');
+    iframe.allow = featurePolicies.join(';') + ';';
+    iframe.src = 'https://{{host}}:{{ports[https][0]}}/generic-sensor/resources/iframe_sensor_handler.html';
+
+    // Create sensor in the iframe (we do not care whether this is a
+    // cross-origin nested context in this test).
+    const iframeLoadWatcher = new EventWatcher(t, iframe, 'load');
+    document.body.appendChild(iframe);
+    await iframeLoadWatcher.wait_for('load');
+
+    // The purpose of this message is to initialize the mock backend in the
+    // iframe. We are not going to use the sensor created there.
+    await send_message_to_iframe(iframe, {command: 'create_sensor',
+                                          type: sensorName});
+
+    const iframeSensor = new iframe.contentWindow[sensorName]();
+    assert_not_equals(iframeSensor, null);
+
+    // Remove iframe from main document. |iframeSensor| no longer has a
+    // non-null browsing context. Calling start() should probably throw an
+    // error when called from a non-fully active document, but that depends on
+    // https://github.com/w3c/sensors/issues/415
+    iframe.parentNode.removeChild(iframe);
+    iframeSensor.start();
+  }, `${sensorName}: calling start() in a non-fully active document does not crash`);
 }

blink/web_tests/external/wpt/geolocation-sensor/GeolocationSensor-iframe-access.https-expected.txt

@@ -2,5 +2,6 @@ This is a testharness.js-based test.
 FAIL GeolocationSensor: sensor is suspended and resumed when focus traverses from to cross-origin frame assert_implements: GeolocationSensor is not supported. undefined
 FAIL GeolocationSensor: sensor is not suspended when focus traverses from to same-origin frame assert_implements: GeolocationSensor is not supported. undefined
 FAIL GeolocationSensor: losing a document's frame with an active sensor does not crash assert_implements: GeolocationSensor is not supported. undefined
+FAIL GeolocationSensor: calling start() in a non-fully active document does not crash assert_implements: GeolocationSensor is not supported. undefined
 Harness: the test ran to completion.
 

blink/web_tests/external/wpt/magnetometer/Magnetometer-iframe-access.https-expected.txt

@@ -2,8 +2,10 @@ This is a testharness.js-based test.
 PASS Magnetometer: sensor is suspended and resumed when focus traverses from to cross-origin frame
 PASS Magnetometer: sensor is not suspended when focus traverses from to same-origin frame
 PASS Magnetometer: losing a document's frame with an active sensor does not crash
+PASS Magnetometer: calling start() in a non-fully active document does not crash
 FAIL UncalibratedMagnetometer: sensor is suspended and resumed when focus traverses from to cross-origin frame assert_implements: UncalibratedMagnetometer is not supported. undefined
 FAIL UncalibratedMagnetometer: sensor is not suspended when focus traverses from to same-origin frame assert_implements: UncalibratedMagnetometer is not supported. undefined
 FAIL UncalibratedMagnetometer: losing a document's frame with an active sensor does not crash assert_implements: UncalibratedMagnetometer is not supported. undefined
+FAIL UncalibratedMagnetometer: calling start() in a non-fully active document does not crash assert_implements: UncalibratedMagnetometer is not supported. undefined
 Harness: the test ran to completion.