super hacky opaque black clear bug workaround

gpu/command_buffer/service/gles2_cmd_decoder_passthrough_doers.cc

Index: gpu/command_buffer/service/gles2_cmd_decoder_passthrough_doers.cc
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder_passthrough_doers.cc b/gpu/command_buffer/service/gles2_cmd_decoder_passthrough_doers.cc
index 3a884f4401a17b95ff85f91fabad43b17e0b7f7e..de6d32fce06554cd04651b1331556552c675946a 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder_passthrough_doers.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder_passthrough_doers.cc
@@ -477,6 +477,7 @@ error::Error GLES2DecoderPassthroughImpl::DoClearColor(GLclampf red,
                                                        GLclampf green,
                                                        GLclampf blue,
                                                        GLclampf alpha) {
+  if (red == 0 && green == 0 && blue == 0 && alpha == 1) alpha = 1.001;
   glClearColor(red, green, blue, alpha);
   return error::kNoError;
 }