Load the GL_KHR_debug entry points and log messages they produce.

gpu/command_buffer/service/gl_utils.h

Index: gpu/command_buffer/service/gl_utils.h
diff --git a/gpu/command_buffer/service/gl_utils.h b/gpu/command_buffer/service/gl_utils.h
index 33b4fd5db7460b40cc4a521ad764a28b7d3cbaa9..9c255cae898fc7f4f1cd439a4a10fe75be10cc32 100644
--- a/gpu/command_buffer/service/gl_utils.h
+++ b/gpu/command_buffer/service/gl_utils.h
@@ -54,6 +54,16 @@ void PopulateNumericCapabilities(Capabilities* caps,
 
 bool CheckUniqueAndNonNullIds(GLsizei n, const GLuint* client_ids);
 
+void APIENTRY LogGLDebugMessage(GLenum source,
+                                GLenum type,
+                                GLuint id,
+                                GLenum severity,
+                                GLsizei length,
+                                const GLchar* message,
+                                GLvoid* user_param);
+
+void InitializeGLDebugLogging();
+
 } // gles2
 } // gpu