Blimp OAuth2 token retreival on application start up.

blimp/client/public/blimp_client_context_delegate.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef BLIMP_CLIENT_PUBLIC_BLIMP_CLIENT_CONTEXT_DELEGATE_H_
 #define BLIMP_CLIENT_PUBLIC_BLIMP_CLIENT_CONTEXT_DELEGATE_H_
 
 #include "base/macros.h"
 #include "blimp/client/public/session/assignment.h"
 
+class IdentityProvider;
+
 namespace blimp {
 namespace client {
 class BlimpContents;
 
 // BlimpClientContextDelegate is how the BlimpClientContext gets the
 // functionality it needs from its embedder.
 class BlimpClientContextDelegate {
  public:
+  // Authentication error propagated to the embedder.
+  enum AuthError {
+    NOT_SIGNED_IN = 0,
+    OAUTH_TOKEN_FAIL,
+  };
+
   virtual ~BlimpClientContextDelegate() = default;
 
   // Attaches any required base::SupportsUserData::Data to the BlimpContents.
   virtual void AttachBlimpContentsHelpers(BlimpContents* blimp_contents) = 0;
 
   // Called whenever an assignment request has finished and the resulting
   // Assignment is ready to be used in an attempt to connect to the engine. The
   // |result| is the result for the assignment request itself, not for the
   // connection attempt. Only when |result| is ASSIGNMENT_REQUEST_RESULT_OK
   // will an attempt actually be made to connect to the engine using the
   // Assignment.
   virtual void OnAssignmentConnectionAttempted(
       AssignmentRequestResult result,
       const Assignment& assignment) = 0;
 
+  // Create IdentityProvider for OAuth2 token retrieval, used in Authenticator.
+  virtual std::unique_ptr<IdentityProvider> CreateIdentityProvider() = 0;
+
+  // Propagate authentication error to the embedder.
+  virtual void OnAuthenticationError(
+      BlimpClientContextDelegate::AuthError error) = 0;
+
  protected:
   BlimpClientContextDelegate() = default;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(BlimpClientContextDelegate);
 };
 
 }  // namespace client
 }  // namespace blimp
 
 #endif  // BLIMP_CLIENT_PUBLIC_BLIMP_CLIENT_CONTEXT_DELEGATE_H_