Make GL calls go through subclassable class.

ui/gl/gl.gyp

Index: ui/gl/gl.gyp
diff --git a/ui/gl/gl.gyp b/ui/gl/gl.gyp
index 32d5e69b776f228b726e3df79c842d52977968b2..d877400f50eb0627a98fdfe751404fce6242d652 100644
--- a/ui/gl/gl.gyp
+++ b/ui/gl/gl.gyp
@@ -53,6 +53,8 @@
         'gl_export.h',
         'gl_fence.cc',
         'gl_fence.h',
+        'gl_gl_api_implementation.cc',
+        'gl_gl_api_implementation.h',
         'gl_image.cc',
         'gl_image.h',
         'gl_image_android.cc',
@@ -69,6 +71,8 @@
         'gl_implementation_win.cc',
         'gl_interface.cc',
         'gl_interface.h',
+        'gl_osmesa_api_implementation.cc',
+        'gl_osmesa_api_implementation.h',
         'gl_share_group.cc',
         'gl_share_group.h',
         'gl_surface.cc',
@@ -114,15 +118,20 @@
           'outputs': [
             '<(gl_binding_output_dir)/gl_bindings_autogen_egl.cc',
             '<(gl_binding_output_dir)/gl_bindings_autogen_egl.h',
+            '<(gl_binding_output_dir)/gl_bindings_autogen_api_egl.h',
             '<(gl_binding_output_dir)/gl_bindings_autogen_gl.cc',
             '<(gl_binding_output_dir)/gl_bindings_autogen_gl.h',
+            '<(gl_binding_output_dir)/gl_bindings_autogen_api_gl.h',
             '<(gl_binding_output_dir)/gl_bindings_autogen_glx.cc',
             '<(gl_binding_output_dir)/gl_bindings_autogen_glx.h',
+            '<(gl_binding_output_dir)/gl_bindings_autogen_api_glx.h',
             '<(gl_binding_output_dir)/gl_bindings_autogen_mock.cc',
             '<(gl_binding_output_dir)/gl_bindings_autogen_osmesa.cc',
             '<(gl_binding_output_dir)/gl_bindings_autogen_osmesa.h',
+            '<(gl_binding_output_dir)/gl_bindings_autogen_api_osmesa.h',
             '<(gl_binding_output_dir)/gl_bindings_autogen_wgl.cc',
             '<(gl_binding_output_dir)/gl_bindings_autogen_wgl.h',
+            '<(gl_binding_output_dir)/gl_bindings_autogen_api_wgl.h',
           ],
           'action': [
             'python',
@@ -140,6 +149,8 @@
             'gl_context_egl.h',
             'gl_surface_egl.cc',
             'gl_surface_egl.h',
+            'gl_egl_api_implementation.cc',
+            'gl_egl_api_implementation.h',
             '<(gl_binding_output_dir)/gl_bindings_autogen_egl.cc',
             '<(gl_binding_output_dir)/gl_bindings_autogen_egl.h',
           ],
@@ -151,10 +162,14 @@
           'sources': [
             'gl_context_glx.cc',
             'gl_context_glx.h',
+            'gl_glx_api_implementation.cc',
+            'gl_glx_api_implementation.h',
             'gl_image_glx.cc',
             'gl_image_glx.h',
             'gl_surface_glx.cc',
             'gl_surface_glx.h',
+            'gl_egl_api_implementation.cc',
+            'gl_egl_api_implementation.h',
             '<(gl_binding_output_dir)/gl_bindings_autogen_glx.cc',
             '<(gl_binding_output_dir)/gl_bindings_autogen_glx.h',
           ],
@@ -174,8 +189,12 @@
           'sources': [
             'gl_context_wgl.cc',
             'gl_context_wgl.h',
+            'gl_egl_api_implementation.cc',
+            'gl_egl_api_implementation.h',
             'gl_surface_wgl.cc',
             'gl_surface_wgl.h',
+            'gl_wgl_api_implementation.cc',
+            'gl_wgl_api_implementation.h',
             '<(gl_binding_output_dir)/gl_bindings_autogen_wgl.cc',
             '<(gl_binding_output_dir)/gl_bindings_autogen_wgl.h',
           ],
@@ -207,6 +226,8 @@
             'android_native_window.h',
           ],
           'sources!': [
+            'gl_egl_api_implementation.cc',
+            'gl_egl_api_implementation.h',
             '<(gl_binding_output_dir)/gl_bindings_autogen_osmesa.cc',
             '<(gl_binding_output_dir)/gl_bindings_autogen_osmesa.h',
             'gl_context_osmesa.cc',