Add a gpu command buffer test for GL_OES_EGL_image extension

Also add some helpers to allow running the gl_tests with EGL / GLES2.

BUG=584248
TEST=gl_tests --gtest_filter=*GpuOESEGLImageTest.EGLImageToTexture*

Cq-Include-Trybots: master.tryserver.chromium.android:android_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel
Change-Id: I5177062eb7c28b59fc2684ef7fc665271b53c12d
Reviewed-on: https://chromium-review.googlesource.com/958908
Reviewed-by: Antoine Labour <[email protected]>
Reviewed-by: Miguel Casas <[email protected]>
Commit-Queue: Miguel Casas <[email protected]>
Cr-Commit-Position: refs/heads/master@{#543403}
diff --git a/gpu/BUILD.gn b/gpu/BUILD.gn
index f583dd1..109eb54 100644
--- a/gpu/BUILD.gn
+++ b/gpu/BUILD.gn
@@ -196,6 +196,7 @@
     "command_buffer/tests/gl_map_buffer_range_unittest.cc",
     "command_buffer/tests/gl_native_gmb_backbuffer_unittest.cc",
     "command_buffer/tests/gl_object_bindings_unittest.cc",
+    "command_buffer/tests/gl_oes_egl_image_unittest.cc",
     "command_buffer/tests/gl_offscreen_surface_unittest.cc",
     "command_buffer/tests/gl_oob_attrib_unittest.cc",
     "command_buffer/tests/gl_pointcoord_unittest.cc",