[PTZ] Fix VideoCaptureDeviceFactoryMacTest PTZ test

This CL makes sure we're testing the value of pan_tilt_zoom_supported()
when checking VideoCaptureDeviceDescriptors on macOS.

Bug: 1095718
Change-Id: I5d3502b571735dd5f1f305f9face2217235944aa
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2247728
Commit-Queue: François Beaufort <beaufort.francois@gmail.com>
Reviewed-by: Mirko Bonadei <mbonadei@chromium.org>
Reviewed-by: Guido Urdaneta <guidou@chromium.org>
Reviewed-by: Eero Häkkinen <eero.hakkinen@intel.com>
Cr-Commit-Position: refs/heads/master@{#779786}

media/capture/video/mac/video_capture_device_factory_mac_unittest.mm

@@ -57,7 +57,7 @@ TEST(VideoCaptureDeviceFactoryMacTest, ListDevicesWithNoPanTiltZoomSupport) {
       return;
     }
     for (const auto& descriptor : descriptors)
-      EXPECT_FALSE(descriptor.pan_tilt_zoom_supported());
+      EXPECT_FALSE(descriptor.pan_tilt_zoom_supported().value());
   }));
 }