gpu: Mark direct composition VP scaling tests as flaky

TBR=zmo@chromium.org

Bug: 1136971
Change-Id: I7cdb1c6e93f36a53a1e650ad2a1aff5da963adbe
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2469899Reviewed-by: Sunny Sachanandani <sunnyps@chromium.org>
Commit-Queue: Sunny Sachanandani <sunnyps@chromium.org>
Cr-Commit-Position: refs/heads/master@{#816857}

content/test/gpu/gpu_tests/test_expectations/trace_test_expectations.txt

@@ -87,6 +87,10 @@ crbug.com/1079393 [ win10 intel-0x3e92 ] OverlayModeTraceTest_DirectComposition_
 crbug.com/1079393 [ win10 intel-0x3e92 ] OverlayModeTraceTest_DirectComposition_Video_VP9_NV12 [ Failure ]
 crbug.com/1079393 [ win10 intel-0x3e92 ] OverlayModeTraceTest_DirectComposition_Video_VP9_YUY2 [ Failure ]
 
+# VP scaling tests are also flaky.
+crbug.com/1136971 [ win10 intel-0x3e92 ] OverlayModeTraceTest_DirectComposition_Video_MP4_VP_SCALING [ RetryOnFailure ]
+crbug.com/1136971 [ win10 intel-0x3e92 ] OverlayModeTraceTest_DirectComposition_Video_VP9_VP_SCALING [ RetryOnFailure ]
+
 # Zero copy also needs scaling to work.
 crbug.com/1079393 [ win10 intel-0x3e92 ] VideoPathTraceTest_DirectComposition_Underlay [ Failure ]
 crbug.com/1079393 [ win10 intel-0x3e92 ] VideoPathTraceTest_DirectComposition_Underlay_DXVA [ Failure ]