[Sheriff] Disable flaky GPU tests on Fuchsia

TBR=bsheedy

Bug: 1087097
Change-Id: I382a3c1e7bf93f7145f7fd4b2b68a6b43da85a00
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2218841Reviewed-by: Jan Wilken Dörrie <jdoerrie@chromium.org>
Commit-Queue: Jan Wilken Dörrie <jdoerrie@chromium.org>
Cr-Commit-Position: refs/heads/master@{#772640}

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

@@ -30,3 +30,9 @@ crbug.com/1084794 [ chromeos ] GpuProcess_swiftshader_for_webgl [ Skip ]
 
 # Software Compositing is not supported on ChromeOS.
 crbug.com/1084796 [ chromeos ] GpuProcess_readback_webgl_gpu_process [ Skip ]
+
+# Flaky on Fuchsia
+crbug.com/1087097 [ fuchsia ] GpuProcess_video [ Skip ]
+crbug.com/1087097 [ fuchsia ] GpuProcess_webgl_disabled_extension [ Skip ]
+crbug.com/1087097 [ fuchsia ] GpuProcess_readback_webgl_gpu_process [ Skip ]
+crbug.com/1087097 [ fuchsia ] GpuProcess_webgl [ Skip ]