UseSkOnce to squelch command buffer spam

tools/gpu/gl/command_buffer/GLTestContext_command_buffer.cpp

Index: tools/gpu/gl/command_buffer/GLTestContext_command_buffer.cpp
diff --git a/tools/gpu/gl/command_buffer/GLTestContext_command_buffer.cpp b/tools/gpu/gl/command_buffer/GLTestContext_command_buffer.cpp
index c644d998e513e3e9d6dadd1204d72683963b9c9a..32e5de4626ebb8aa05996cac7b0041ab432bd2e8 100644
--- a/tools/gpu/gl/command_buffer/GLTestContext_command_buffer.cpp
+++ b/tools/gpu/gl/command_buffer/GLTestContext_command_buffer.cpp
@@ -185,7 +185,8 @@ void CommandBufferGLTestContext::initializeGLContext(void *nativeWindow, const i
                                                  const int *surfaceAttribs) {
     load_command_buffer_once();
     if (!gfFunctionsLoadedSuccessfully) {
-        SkDebugf("Command Buffer: Could not load EGL functions.\n");
+        static SkOnce once;
+        once([] { SkDebugf("Command Buffer: Could not load EGL functions.\n"); });
         return;
     }