Add usage counter to OffscreenCanvas API calls

third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.idl

 /*
  * Copyright (C) 2009 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 688 matching lines @@
     void vertexAttrib3fv(GLuint indx, Float32Array values);
     void vertexAttrib3fv(GLuint indx, sequence<GLfloat> values);
     void vertexAttrib4f(GLuint indx, GLfloat x, GLfloat y, GLfloat z, GLfloat w);
     void vertexAttrib4fv(GLuint indx, Float32Array values);
     void vertexAttrib4fv(GLuint indx, sequence<GLfloat> values);
     void vertexAttribPointer(GLuint indx, GLint size, GLenum type, GLboolean normalized,
                                                     GLsizei stride, GLintptr offset);
 
     void viewport(GLint x, GLint y, GLsizei width, GLsizei height);
 
-    [RuntimeEnabled=ExperimentalCanvasFeatures, RaisesException] void commit();
+    [RuntimeEnabled=ExperimentalCanvasFeatures, RaisesException, MeasureAs=OffscreenCanvasCommit] void commit();

[Justin Novosad, 2016/10/13 00:33:46]

I think you should use separate counters for 2D and WebGL

 };