Fix flaky pointermove on chorded buttons when locked test

Pointer lock is acquired and released asynchronously. Remove
reliance on timeout from the test by waiting until lock is
properly acquired/released during the test steps.

Bug: 1025944
Change-Id: Ibd5b1c19efb9c00794f1b900e12a5f5a4edab16e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2360494Reviewed-by: Mustaq Ahmed <mustaq@chromium.org>
Commit-Queue: Liviu Tinta <liviutinta@chromium.org>
Cr-Commit-Position: refs/heads/master@{#800553}

third_party/blink/web_tests/TestExpectations

@@ -6568,7 +6568,6 @@ crbug.com/1098067 [ Fuchsia ] virtual/text-antialias/bidi-isolate-nextlinebreak-
 
 # Sheriff 2020-06-23
 crbug.com/1098136 [ Linux ] virtual/android/fullscreen/video-fixed-background.html [ Failure ]
-crbug.com/1025944 [ Linux ] external/wpt/pointerevents/pointerlock/pointerevent_pointermove_on_chorded_mouse_button_when_locked.html [ Pass Failure ]
 
 # Sheriff 2020-06-24
 crbug.com/1098676 [ Win ] http/tests/devtools/console-xhr-logging.js [ Pass Failure ]

third_party/blink/web_tests/external/wpt/pointerevents/pointerlock/pointerevent_pointermove_on_chorded_mouse_button_when_locked.html

@@ -35,7 +35,7 @@
             var firstButton = 0;
             var pointer_locked = false;
 
-            function run() {
+            async function run() {
                 var target0 = document.getElementById("target0");
 
                 // When a pointer changes button state and the circumstances produce no other pointer event, the pointermove event must be dispatched.
@@ -44,7 +44,9 @@
                 on_event(target0, "pointerdown", function (event) {
                     if (pointer_locked) {
                         detected_pointertypes[event.pointerType] = true;
-                        test_pointermove.step(function() {assert_true(step === 0, "There must not be more than one pointer down event.");});
+                        test_pointermove.step(function() {
+                            assert_true(step === 0, "There must not be more than one pointer down event.");
+                        });
                         if (step == 0) {
                             step = 1;
                             firstButton = event.buttons;
@@ -56,11 +58,17 @@
                         detected_pointertypes[event.pointerType] = true;
 
                         if (step == 1 && event.button != -1) { // second button pressed
-                            test_pointermove.step(function() {assert_true(event.buttons !== firstButton, "The pointermove event must be triggered by pressing a second button.");});
-                            test_pointermove.step(function() {assert_true((event.buttons & firstButton) != 0, "The first button must still be reported pressed.");});
+                            test_pointermove.step(function() {
+                                assert_true(event.buttons !== firstButton, "The pointermove event must be triggered by pressing a second button.");
+                            });
+                            test_pointermove.step(function() {
+                                assert_true((event.buttons & firstButton) != 0, "The first button must still be reported pressed.");
+                            });
                             step = 2;
                         } else if (step == 2 && event.button != -1) { // second button released
-                            test_pointermove.step(function() {assert_true(event.buttons === firstButton, "The pointermove event must be triggered by releasing the second button.");});
+                            test_pointermove.step(function() {
+                                assert_true(event.buttons === firstButton, "The pointermove event must be triggered by releasing the second button.");
+                            });
                             step = 3;
                         }
                     }
@@ -68,14 +76,13 @@
                 on_event(target0, "pointerup", function (event) {
                     if (pointer_locked) {
                         detected_pointertypes[event.pointerType] = true;
-                        step_timeout(function() {
-                            test_pointermove.step(function() {assert_true(step === 3, "The pointerup event must be triggered after pressing and releasing the second button.");});
-                            test_pointermove.step(function() {assert_true(event.buttons === 0, "The pointerup event must be triggered by releasing the last pressed button.");});
-                            document.exitPointerLock();
-                            actions_promise.then( () => {
-                                test_pointermove.done();
-                            });
-                        }, 500);
+                        test_pointermove.step(function() {
+                            assert_true(step === 3, "The pointerup event must be triggered after pressing and releasing the second button.");
+                        });
+                        test_pointermove.step(function() {
+                            assert_true(event.buttons === 0, "The pointerup event must be triggered by releasing the last pressed button.");
+                        });
+                        document.exitPointerLock();
                     } else {
                         target0.requestPointerLock();
                     }
@@ -83,8 +90,12 @@
                 on_event(document, 'pointerlockchange', function(event) {
                     if (document.pointerLockElement == target0)
                         pointer_locked = true;
-                    else
+                    else{
                         pointer_locked = false;
+                        actions_promise.then( () => {
+                           test_pointermove.done();
+                        });
+                    }
                 });
                 on_event(target0, "mouseup", function (event) {
                     event.preventDefault();
@@ -95,9 +106,16 @@
 
                 // Inject mouse input
                 var actions = new test_driver.Actions();
-                actions_promise = actions.pointerMove(0, 0, {origin: target0})
+                actions_promise = actions
+                       .pointerMove(0, 0, {origin: target0})
                        .pointerDown({button: actions.ButtonType.LEFT})
                        .pointerUp({button: actions.ButtonType.LEFT})
+                       .send();
+                await actions_promise;
+                await resolveWhen(()=>pointer_locked);
+                actions = new test_driver.Actions();
+                actions_promise = actions
+                       .pointerMove(0, 0, {origin: target0})
                        .pointerDown({button: actions.ButtonType.LEFT})
                        .pointerDown({button: actions.ButtonType.MIDDLE})
                        .pointerUp({button: actions.ButtonType.MIDDLE})