Update tests to check XRInputSource profiles + gamepad.id

Per the latest WebXR spec, XRInputSource.gamepad.id must be the empty
string. Update the browser and layout tests to actually check this.

Also update the browser tests that run on Windows to check the profiles
array contents against expected values for WMR and OpenVR.

Bug: 989114, 942201
Change-Id: I36dff42cff55728d5d90384623623ea871d3a13e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1742439
Commit-Queue: Jacob DeWitt <jacde@chromium.org>
Reviewed-by: Brian Sheedy <bsheedy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#685270}

Author: Jacob DeWitt

webxr/xrInputSource_gamepad_disconnect.https.html

@@ -77,6 +77,8 @@
       "Expect to have a gamepad, iteration: " + inputChangeEvents);
     assert_equals(cached_input_source.gamepad.index, -1,
       "WebXR Gamepad.index must be -1, iteration: " + inputChangeEvents);
+    assert_equals(cached_input_source.gamepad.id, "",
+      "WebXR Gamepad.id must be empty string, iteration: " + inputChangeEvents);
     assert_true(cached_input_source.gamepad.connected,
       "Expect the gamepad to be connected, iteration: " + inputChangeEvents);
   }
@@ -88,6 +90,8 @@
       "Expect to have a gamepad on cached_input_source, iteration: " + inputChangeEvents);
     assert_equals(cached_input_source.gamepad.index, -1,
       "WebXR Gamepad.index must be -1, iteration: " + inputChangeEvents);
+    assert_equals(cached_input_source.gamepad.id, "",
+      "WebXR Gamepad.id must be empty string, iteration: " + inputChangeEvents);
     assert_false(cached_input_source.gamepad.connected,
       "Expect cached gamepad to be disconnected, iteration: " + inputChangeEvents);
   }

webxr/xrInputSource_gamepad_input_registered.https.html

@@ -52,7 +52,11 @@
   function assertSameObjects() {
     assert_equals(session.inputSources[0], cached_input_source);
     assert_equals(cached_input_source.gamepad, cached_gamepad);
+
+    // Also make sure that WebXR gamepads have the index and id values required
+    // by the spec.
     assert_equals(cached_gamepad.index, -1);
+    assert_equals(cached_gamepad.id, "");
   }
 
   // Input events and gamepad state changes (button presses, axis movements)
@@ -74,6 +78,7 @@
       cached_gamepad = cached_input_source.gamepad;
       t.step(() => {
         assert_equals(cached_gamepad.index, -1);
+        assert_equals(cached_gamepad.id, "");
         assert_equals(cached_gamepad.buttons.length, 3);
         assert_equals(cached_gamepad.axes.length, 2);
         // Initially, the button should not be pressed and the axes values should