See crrev.com/2729523002 for context:

MailboxToSurfaceBridge::CreateSurface(...) {
  // Our attributes must be compatible with the shared offscreen
  // surface used by virtualized contexts, otherwise mailbox
  // synchronization doesn't work properly - it assumes a shared
  // underlying GL context. 

Can we use GetCompositorContextAttributes from 
content/browser/renderer_host/compositor_impl_android.cc to avoid 
duplicate configuration? This would need a public content compositor.h
export similar to that added in crrev.com/2731833002.