From Anupam: 
"//src/content/browser/webauth/authenticator_impl.cc
needs to do something like

BrowserContext* browser_context =
      render_frame_host->GetProcess()->GetBrowserContext();
 StoragePartition* storage_partition =
      BrowserContext::GetDefaultStoragePartition(browser_context);


and then, like in 
//src/extensions/browser/api/messaging/message_property_provider.cc
void MessagePropertyProvider::GetChannelID()
asynchronously get the appropriate channel id."

Kim, what's the urgency of this? Can you please update it below?

(Removing OWNER for the moment until priority is defined.)

It's not urgent, but it'd be nice to have for M68.

Note also that Token Binding is still controlled by a flag, which will need to be taken into account when adding support. https://cs.chromium.org/chromium/src/components/network_session_configurator/common/network_features.cc