gpu: Add ARB_occlusion_query support.

gpu/command_buffer/service/feature_info.cc

Index: gpu/command_buffer/service/feature_info.cc
diff --git a/gpu/command_buffer/service/feature_info.cc b/gpu/command_buffer/service/feature_info.cc
index 45062e16dc8d43531a6d3be0da9c39860fd0e2e7..08d65c9fdf194d2930665dd24dbe8b5d3a9853b0 100644
--- a/gpu/command_buffer/service/feature_info.cc
+++ b/gpu/command_buffer/service/feature_info.cc
@@ -129,6 +129,7 @@ FeatureInfo::FeatureFlags::FeatureFlags()
       angle_pack_reverse_row_order(false),
       arb_texture_rectangle(false),
       angle_instanced_arrays(false),
+      occlusion_query(false),
       occlusion_query_boolean(false),
       use_arb_occlusion_query2_for_occlusion_query_boolean(false),
       use_arb_occlusion_query_for_occlusion_query_boolean(false),
@@ -1179,6 +1180,7 @@ void FeatureInfo::InitializeFeatures() {
       have_ext_occlusion_query_boolean ||
       have_arb_occlusion_query2 ||
       have_arb_occlusion_query) {
+    feature_flags_.occlusion_query = have_arb_occlusion_query;

[jbauman, 2017/01/19 01:33:43]

I think this was promoted to core in OpenGL 1.5 (desktop), so you should check
for that as well.

[reveman, 2017/01/19 04:44:34]

Good call. Added it to the have_arb_occlusion_query check in latest patch.

     if (context_type_ == CONTEXT_TYPE_OPENGLES2) {
       AddExtensionString("GL_EXT_occlusion_query_boolean");
     }