fix --show-composited-layer-borders on Mac

gpu/command_buffer/build_gles2_cmd_buffer.py

Index: gpu/command_buffer/build_gles2_cmd_buffer.py
diff --git a/gpu/command_buffer/build_gles2_cmd_buffer.py b/gpu/command_buffer/build_gles2_cmd_buffer.py
index 49518430b545ed91b835d9c2168106ed3692ba2b..7449efede1d005cc861cabac9397a36205594983 100755
--- a/gpu/command_buffer/build_gles2_cmd_buffer.py
+++ b/gpu/command_buffer/build_gles2_cmd_buffer.py
@@ -2740,9 +2740,8 @@ _FUNCTION_INFO = {
   'FrontFace': {'type': 'StateSet', 'state': 'FrontFace'},
   'DepthFunc': {'type': 'StateSet', 'state': 'DepthFunc'},
   'LineWidth': {
-    'type': 'StateSet',
+    'type': 'Custom',

[piman, 2016/11/07 19:38:01]

Rather than using "Custom" which completely removes the autogenerated code, can
you use a regular function (remove the 'type' attribute, leaving the
decoder_func), and move the logic (extra validation, state tracking) to the
DoLineWidth function?

     'state': 'LineWidth',
-    'decoder_func': 'DoLineWidth',
     'valid_args': {
       '0': '2.0f'
     },