gpu: Add direct composition pixel test for overlays disabled case

Support for direct composition pixel tests which do not use overlays has
been added, so use that for testing that video overlays are not used
when disabled.  This would have prevented a recent regression.

Bug: 1007055
Change-Id: Ic7fdf5524ca7e85bac8499cdf023c9b13f2c7b90
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1829252
Commit-Queue: Sunny Sachanandani <sunnyps@chromium.org>
Auto-Submit: Sunny Sachanandani <sunnyps@chromium.org>
Reviewed-by: Zhenyao Mo <zmo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#701377}

content/test/gpu/gpu_tests/pixel_test_pages.py

@@ -1785,4 +1785,14 @@ class PixelTestPages(object):
         browser_args=browser_args,
         other_args={'no_overlay': True},
         tolerance=tolerance_dc),
+
+      PixelTestPage(
+        'pixel_video_mp4.html',
+        base_name + '_DirectComposition_Video_Disable_Overlays',
+        test_rect=[0, 0, 240, 135],
+        revision=0, # Golden image revision is not used
+        browser_args=['--disable-direct-composition-video-overlays'],
+        other_args={'no_overlay': True},
+        tolerance=tolerance_dc,
+        expected_colors=_FOUR_COLOR_VIDEO_240x135_EXPECTED_COLORS),
       ]