command_buffer_gles2: Implement EGL default Display as a global object

gpu/gles2_conform_support/egl/BUILD.gn

Index: gpu/gles2_conform_support/egl/BUILD.gn
diff --git a/gpu/gles2_conform_support/egl/BUILD.gn b/gpu/gles2_conform_support/egl/BUILD.gn
index ee06fbf32642cf739ef9b50bd790241c92126ff6..731237db47c861f1db6274e7bc3eea780dca5fc9 100644
--- a/gpu/gles2_conform_support/egl/BUILD.gn
+++ b/gpu/gles2_conform_support/egl/BUILD.gn
@@ -8,11 +8,15 @@ source_set("egl") {
   sources = [
     "config.cc",
     "config.h",
+    "context.cc",
+    "context.h",
     "display.cc",
     "display.h",
     "egl.cc",
     "surface.cc",
     "surface.h",
+    "thread_state.cc",
+    "thread_state.h",
   ]
 
   configs += [ "//build/config/compiler:no_size_t_to_int_warning" ]
@@ -26,6 +30,7 @@ source_set("egl") {
     "//base",
     "//gpu",
     "//gpu/command_buffer/client:gles2_implementation_no_check",
+    "//gpu/command_buffer/common:gles2_utils",
     "//gpu/command_buffer/service",
     "//ui/base",
     "//ui/gfx",