Disable test SharedImageBackingFactoryAHBTest.OnlyOneWriter.

This test is failing on multiple builders.

TBR=bajones@chromium.org

Bug: 994720
Change-Id: I656c207acc63e5ee03d44422ff17ad47de8afccc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1776862Reviewed-by: Xing Liu <xingliu@chromium.org>
Commit-Queue: Xing Liu <xingliu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#691841}

gpu/command_buffer/service/shared_image_backing_factory_ahardwarebuffer_unittest.cc

@@ -303,8 +303,9 @@ TEST_F(SharedImageBackingFactoryAHBTest, EstimatedSize) {
   shared_image.reset();
 }
 
+// TODO(crbug/994720): Failing on Android builders.
 // Test to check that only one context can write at a time
-TEST_F(SharedImageBackingFactoryAHBTest, OnlyOneWriter) {
+TEST_F(SharedImageBackingFactoryAHBTest, DISABLED_OnlyOneWriter) {
   if (!base::AndroidHardwareBufferCompat::IsSupportAvailable())
     return;