Add glGetShaderPrecisionFormat

Review URL: https://codereview.chromium.org/778703003
diff --git a/include/gpu/gl/GrGLFunctions.h b/include/gpu/gl/GrGLFunctions.h
index 0b7beb6..3a94058 100644
--- a/include/gpu/gl/GrGLFunctions.h
+++ b/include/gpu/gl/GrGLFunctions.h
@@ -140,6 +140,7 @@
     typedef GrGLvoid (GR_GL_FUNCTION_TYPE* GrGLGetRenderbufferParameterivProc)(GrGLenum target, GrGLenum pname, GrGLint* params);
     typedef GrGLvoid (GR_GL_FUNCTION_TYPE* GrGLGetShaderInfoLogProc)(GrGLuint shader, GrGLsizei bufsize, GrGLsizei* length, char* infolog);
     typedef GrGLvoid (GR_GL_FUNCTION_TYPE* GrGLGetShaderivProc)(GrGLuint shader, GrGLenum pname, GrGLint* params);
+    typedef GrGLvoid (GR_GL_FUNCTION_TYPE* GrGLGetShaderPrecisionFormatProc)(GrGLenum shadertype, GrGLenum precisiontype, GrGLint *range, GrGLint *precision);
     typedef const GrGLubyte* (GR_GL_FUNCTION_TYPE* GrGLGetStringProc)(GrGLenum name);
     typedef const GrGLubyte* (GR_GL_FUNCTION_TYPE* GrGLGetStringiProc)(GrGLenum name, GrGLuint index);
     typedef GrGLvoid (GR_GL_FUNCTION_TYPE* GrGLGetTexLevelParameterivProc)(GrGLenum target, GrGLint level, GrGLenum pname, GrGLint* params);