Refactor GL bindings so there is no global GLApi or DriverGL.

ui/gl/BUILD.gn

Index: ui/gl/BUILD.gn
diff --git a/ui/gl/BUILD.gn b/ui/gl/BUILD.gn
index 360551d76548c2cde1a653536f54702c2bc203f3..3dd0569eb7f6c2f6757854949f6426e1a5f4dfa3 100644
--- a/ui/gl/BUILD.gn
+++ b/ui/gl/BUILD.gn
@@ -55,8 +55,12 @@ component("gl") {
     "ca_renderer_layer_params.h",
     "gl_bindings.cc",
     "gl_bindings.h",
-    "gl_bindings_autogen_gl.cc",
     "gl_bindings_autogen_gl.h",
+    "gl_bindings_autogen_gl0.cc",
+    "gl_bindings_autogen_gl1.cc",
+    "gl_bindings_autogen_gl2.cc",
+    "gl_bindings_autogen_gl3.cc",
+    "gl_bindings_autogen_gl4.cc",
     "gl_bindings_autogen_osmesa.cc",
     "gl_bindings_autogen_osmesa.h",
     "gl_context.cc",
@@ -65,8 +69,6 @@ component("gl") {
     "gl_context_osmesa.h",
     "gl_context_stub.cc",
     "gl_context_stub.h",
-    "gl_context_stub_with_extensions.cc",
-    "gl_context_stub_with_extensions.h",
     "gl_enums.cc",
     "gl_enums.h",
     "gl_enums_implementation_autogen.h",
@@ -122,8 +124,6 @@ component("gl") {
     "gpu_switching_manager.h",
     "gpu_timing.cc",
     "gpu_timing.h",
-    "scoped_api.cc",
-    "scoped_api.h",
     "scoped_binders.cc",
     "scoped_binders.h",
     "scoped_make_current.cc",