Remove the GrGLInterface callback mechanism.

include/gpu/gl/GrGLConfig.h

Index: include/gpu/gl/GrGLConfig.h
diff --git a/include/gpu/gl/GrGLConfig.h b/include/gpu/gl/GrGLConfig.h
index c91537cc380a891f2023527bb58b9519bb1ccfac..82963a75200764b06cf46c41c78d0bb9b312f705 100644
--- a/include/gpu/gl/GrGLConfig.h
+++ b/include/gpu/gl/GrGLConfig.h
@@ -56,15 +56,6 @@
  * Chrome's cmd buffer will create a new allocation and memset the whole thing
  * to zero (for security reasons). Defaults to 1 (enabled).
  *
- * GR_GL_PER_GL_FUNC_CALLBACK: When set to 1 the GrGLInterface object provides
- * a function pointer that is called just before every gl function. The ptr must
- * be valid (i.e. there is no NULL check). However, by default the callback will
- * be set to a function that does nothing. The signature of the function is:
- *    void function(const GrGLInterface*)
- * It is not extern "C".
- * The GrGLInterface field fCallback specifies the function ptr and there is an
- * additional field fCallbackData of type intptr_t for client data.
- *
  * GR_GL_CHECK_ALLOC_WITH_GET_ERROR: If set to 1 this will then glTexImage,
  * glBufferData, glRenderbufferStorage, etc will be checked for errors. This
  * amounts to ensuring the error is GL_NO_ERROR, calling the allocating
@@ -115,10 +106,6 @@
     #define GR_GL_USE_BUFFER_DATA_NULL_HINT             1
 #endif
 
-#if !defined(GR_GL_PER_GL_FUNC_CALLBACK)
-    #define GR_GL_PER_GL_FUNC_CALLBACK                  0
-#endif
-
 #if !defined(GR_GL_CHECK_ALLOC_WITH_GET_ERROR)
     #define GR_GL_CHECK_ALLOC_WITH_GET_ERROR            1
 #endif